Genet Resour Crop Evol (2009) 56:947–961
DOI 10.1007/s10722-009-9413-7
RESEARCH ARTICLE
Phenotypic diversity within native Iranian almond
(Prunus spp.) species and their breeding potential
K. Sorkheh Æ B. Shiran Æ V. Rouhi Æ E. Asadi Æ
H. Jahanbazi Æ H. Moradi Æ T. M. Gradziel Æ
P. Martı́nez-Gómez
Received: 20 November 2007 / Accepted: 26 January 2009 / Published online: 4 March 2009
Ó Springer Science+Business Media B.V. 2009
Abstract A total of 137 accessions from 18 wild
almond species were collected from Iran and leaf and
fruit traits were characterized. Also evaluated were
flowering and ripening date, self-incompatibility and
kernel bitterness. An extensive phenotypic diversity
was found both among and within species. Differences
in average leaf dimensions among and within species
were associated with average rainfall but not altitude of
K. Sorkheh B. Shiran V. Rouhi
Department of Agronomy and Plant Breeding, Faculty of
Agriculture, Shahrekord University, P.O. Box 115,
Shahrekord, Iran
E. Asadi
Department of Natural Resources, Faculty of Agriculture,
Shahrekord University, P.O. Box 115, Shahrekord, Iran
H. Jahanbazi
Section of Natural Resources, Agriculture and Natural
Resources Research Center of Shahrekord,
P.O. Box 88155-415, Shahrekord, Iran
H. Moradi
Section of Horticulture, Agriculture and Natural
Resources Research Center of Shahrekord,
P.O. Box 88155-415, Shahrekord, Iran
T. M. Gradziel
Department of Plant Science, University of California,
Davis, CA 95616, USA
P. Martı́nez-Gómez (&)
Department of Plant Breeding, CEBAS-CSIC,
P.O. Box 164, 30100 Espinardo, Murcia, Spain
e-mail: pmartinez@cebas.csic.es
collection site. Adjacent accessions located in drier
areas had smaller leaf dimensions than those located in
semi-humid or humid regions. No relation was found
between average fruit dimensions and collection site
conditions. Principal component analysis revealed that
the nut weight and width, and the kernel weight had
highest loading in the first component accounting for
45.8% of total variation. In contrast, leaf traits in the
second component accounted for 22.3% of total
variation. No significant correlations were detected
between leaf dimensions and fruit traits in all species
evaluated. Results document a rich source of new
germplasm for almond improvement programs. Small
fruit size, pollen-pistil self-incompatibility, and bitter
kernel flavour are the most common obstacles to the
utilization of this wild germplasm in breeding.
Keywords Bitterness Breeding Diversity
index Drought resistance Frost resistance
Germplasm Morphological diversity Pest
resistance Prunus dulcis Self-incompatibility
Introduction
Iran, with a total land area of 1,648,195 square
kilometers, lies between 25° and 39° N latitude and
44° and 63° E longitude and is primarily subtropical
in the southern half of the country, temperate in the
123
948
Genet Resour Crop Evol (2009) 56:947–961
Fig. 1 Geographical
locations of the wild
almond species populations
collected in Iran
northern half part, and mostly desert in the middle
(Fig. 1). The resultant variability in environment and
climate has made possible an extensive diversity of
plant germplasm (Ghahreman and Attar 1999).
Almond [Prunus dulcis (Mill.) D.A. Webb syn.
P. amygdalus (L.) Batsch] production in Iran is based
on locally adapted clones, with minimum to no
inputs, and traditional management. Wild almond
species commonly grow in areas between 28° and
38° N and 41° and 54° E and from 1,100 m to
2,700 m altitudes (Komarov et al. 1941; Browicz
1969; Rickter 1972; Grasselly 1976a; Denisov 1988;
Kester et al. 1991). Nearly 20 of these wild species
have been reported in Iran (Etemadi and Asadi 1999;
Safaei 1999; Ghahreman and Attar 1999; Moradi
2005; Gorttapeh et al. 2005) indicating that Iran is
within the centre of origin for almond (Grasselly
1976b; Ladizinsky 1999). From the taxonomy point
of view, these wild species together with the almond
were placed in an independent genus Amygdalus L.
(Browicz 1969; Serafinov 1971; Zohary 1983; Browicz
and Zohary 1996) outside of the genus Prunus L.
Later, Grasselly (1976a; 1992) placed this group of
species in a subgenus Amygdalus L. inside the genus
Prunus. More recently different authors recommended to place the almond species within the
Prunus; and to avoid considering them as a separate
genus (Kester et al. 1991; Kester and Gradziel 1996;
123
Socias i Company 1998; Gradziel et al. 2001). Both
treatments are taxonomically ‘legal’ and the decision
to keep this group of species as an independent genus
is a matter of personal interpretation (Zohary 1998).
The limited gene pool in cultivated almond limits
the cultivation to specific areas with Mediterranean
climate. Related almond species demonstrate a
greater resistance to abiotic and biotic stresses and
so represent valuable germplasm sources for breeding
(Gradziel et al. 2001). Crosses between almond and
related species have been successful (Bernhard 1949;
Grasselly 1976a; Felipe and Socias i Company 1977;
Kester and Gradziel 1996; Gradziel and Kester 1998)
and numerous spontaneous interspecific hybrids have
been reported (Serafinov 1971; Denisov 1988; Browicz
and Zohary 1996). Interspecific hybrids between
these related species including peach [P. persica (L.)
Batsch] 9 almond, and P. webbii Spach 9 peach
have been previously used long time for almond
rootstock breeding in France (Bernhard 1949), USA
(Kester and Hansen 1966), Spain (Felipe 1975) or
Yugoslavia (Vlasic 1977). In addition, many of these
species have been used directly as a rootstocks for
almond usually for non-irrigated conditions including
P. spartioides Spach (Gentry 1956) in Iran; P.
bucharica (Korsh.) Hand.-Mazz. (Evreinoff 1952;
Jadrov 1970) and P. fenzliana Fritsch (Denisov 1980)
in Russia; P. webbii (Dimitrovski and Ristevski
Genet Resour Crop Evol (2009) 56:947–961
1973) in Turkey; and P. fenzliana, P. bucharica, P.
kuramica Korsh. and P. argentea Lam. (Grasselly
1976a) or P. dehiscens Koehne and P. kotschyi
(Boiss. et Hohen.) Nab. (Grasselly 1992) in France.
Until recently, the utilization in almond breeding of
related species has been limited to the interspecific
introgression of self-compatibility genes (Socias i
Company and Felipe 1992; Gradziel and Kester
1998). Felipe (1984) introgressed self-compatibility
to new Spanish almond varieties from other wild
species. In this program, P. scoparia (Spach) C.K.
Schneid., P. fenzliana, P. kuramica, P. spinosissima
Franch. and P. webbii, were used as sources of selfcompatibility. Socias i Company (1992) also describe
P. persica (L.) Batsch and P. webbii useful sources
for self-compatibility for cultivated almonds. Finally,
Denisov (1988) describes in Russia the utilization of
P. mira Koehne and P. persica as a source of selfcompatibility in his breeding program.
The wide adaptation of the related wild almond
species indicate their potential as sources for resistance to abiotic and biotic stresses as well as modified
tree and nut traits. The objective of this work was a
more thorough assessment of phenotypic diversity of
these wild species from different geographical points
of Iran and the evaluation of their potential in
breeding cultivated almonds.
Materials and methods
Wild almond species
Wild almond species studied included in the genus
Prunus, subgenus Amygdalus, were P. carduchorum
(Bornm.) Neikle, P. communis (L.) Archang., P.
elaeagnifolia (Spach) Fritsch, P. fenzliana Fritsch, P.
korschinskyi Hand.-Mazz., P. kotschyi (Boiss. et
Hohen.) Nab., P. orientalis Mill. (syn. P. argentea
Lam.) and P. trichamygdalus Hand.-Mazz. in section
Euamygdalus Spach; P. eburnea Spach, P. erioclada
Bornm., P. lycioides Spach, P. reuteri Boiss. et Bushe
and P. urumiensis Bornm. in section Lycioides Spach;
and P. arabica (Olivier) Neikle, P. glauca (Browicz)
A.E. Murray, P. haussknechtii (C.K. Schneid.)
Bornm., P. pabotii Browicz and P. scoparia Spach
in section Spartioides Spach (Grasselly 1976a; Kester
and Gradziel 1996; Socias i Company 1998). The
number of accessions sampled per site ranged from
949
one to five, depending on habitat diversity and
availability at collection time. A total of 137 accessions were collected from the 18 studied species
(Tables 2 and 3).
Collecting regions
Field expeditions were carried out in 2005 and 2006.
Sites were selected based on previous literature
(Etemadi and Asadi 1999; Moradi 2005; Gorttapeh
et al. 2005), indigenous information, or conspicuous
presence. Collections were made from both wild and
cultivated habitats, which were concentrated in two
different regions in Iran. The first region (Azerbaijan
and Kurdistan) is characterized by a relatively lush
environment, a high biological diversity, and relatively low agricultural development. The second
region (Shahrekord and Shiraz) is in a more xerophytic region with widespread agriculture (Table 1;
Fig. 1).
Evaluation of leaf and fruit traits
Characterization of leaf and fruits was based on
almond descriptors developed by the International
Plant Genetic Resources Institute (IPGRI) (Gulcan
1985). Four leaf traits including leaf length (cm), leaf
width (cm), petiole length (cm) and internode length
(cm) were evaluated; and five fruit traits including
nut weigh (g), nut width (mm), nut length (mm), shell
thickness (mm), and kernel weight (g), were evaluated. Measurements were scored for 10 fruits and 50
leaves per accession.
Evaluation of agronomical traits
Agronomic traits evaluated included flowering date
(evaluated from January to March as relatively early,
middle, late and very late within this period), pollenpistil compatibility (evaluated by bagging flowers and
characterizing resultant fruit set as self-compatible
(i.e. fruit set comparable to nearby open-pollinated
branches) or self-incompatible (no set to very low
set), ripening date (evaluated from August to October
as early, middle, late and very late within this period)
and kernel bitterness (evaluated by tasting sample
almonds by two individuals and classifying each
genotype as sweet, slightly bitter or bitter).
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950
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Table 1 Geographic and climatic information of the regions where the wild almond species were collected
Province
Location of population
Latitude N
Longitude E
Elevation (m)
East Azerbaijan
Marand
38.28
45.46
1550.0
West Azerbaijan
Mahabad
36.46
45.43
1385.0
413.1
Oroomeih
Piranshahr
37.32
36.40
45.50
45.80
1315.9
1455.0
341.0
672.7
Salmas
38.13
44.51
1337.0
228.7
Sardasht
36.9
45.30
1670.0
866.0
Kurdistan
Baneh
36.0
45.54
1600.0
689.3
Shahrekord
Ardal
32.01
49.50
1850.0
320.2
Bazoft
Shiraz
–
–
338.3
458.9
Boroojen
31.57
51.18
2197.0
254.3
Farsan
32.15
50.35
2250.0
275.4
Felard
31.17
51.22
1970.0
456.8
Kareh-e- Base
31.30
45.54
2700.0
283.2
Koohrang
32.26
50.70
2285.0
1441.8
Lordegan
31.30
50.49
1580.0
567.3
Mountain’s Saman
30.32
50.59
2085.0
280.3
Saman
27.32
56.50
2085.0
280.3
Shahrekord
32.17
50.51
2048.9
321.5
Mianjangale station
28.58
53.41
1288.3
293.1
Statistical analyses
A phenotypic diversity index, (hs.J = R pi ln pi) was
calculated according to Hutchenson (1970) for each
leaf and fruit trait and specie. In addition, a principal
component analysis was performed using the standardized mean values for accessions from each
species. This statistical procedure reduces the dimensions of the original data matrix and transforms
independent variables into autonomous ones (for
purpose of interpretation, matrix loadings greater
than 0.6 were considered significant). Finally, a
correlation analysis among leaf and fruit traits was
performed. All statistical analyses were performed
using SAS (SAS Institute, Cary, North Carolina).
Results and discussion
Leaf traits
Leaf dimensions encompassed an extensive range
between the largest species (P. fenzliana, 8.4 cm
length and 1.9 cm width on average) and the smallest
one (P. erioclada, 0.9 cm length and 0.5 cm width)
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–
Annual rainfall (mm)
(Table 2). Scored leaf traits included nine leaf shapes
(linear lanceolate, lanceolate, oblanceolate, oblonglanceolate, ovate-lanceolate, oblong, oval, elliptical
and obovate), two leaf margin shapes (entire and
crenate), four leaf apex shapes (acute, obtuse, acuteobtuse, notched) and presence or absence of spines.
Petiole length ranged between 1.5 cm (P. fenzliana)
and 0.3 cm (P. pabotii) and internode length between
1.5 cm (P. urumiensis) and 0.8 cm (P. eburnea). Leaf
traits differences species were found to be associated
with environment since populations located in drier
areas had different leaf sizes than those located in
semi-humid or more humid regions. For paired
populations within species, accessions from the
locations that receive greater annual rainfall always
had greater leaf dimensions.
Within the section Euamygdalus, all P. carduchorum
accessions had linear-lanceolate to narrowly
obovate leaf shape. Leaf margins were entire in all
accessions, while leaf apices were acute. Within P.
communis, leaf shapes were different among populations ranging from linear lanceolate to obovate.
Within P. elaeagnifolia (Fig. 2), leaf shapes differed
among populations, varying among oval, oblong and
obovate, with the Mianjangale consistently showing
Genet Resour Crop Evol (2009) 56:947–961
951
Table 2 Evaluation of leaf traits in the wild almond species studied
Section
Species
Euamygdalus P. carduchorum
P. communis
Location of
population
Leaf length Leaf width Petiole length Internode length
No of
(cm)
(cm)
(cm)
accessions (cm)
Mahabad
2
4.4 ± 1.25
0.4 ± 0.05
–
0.9 ± 0.22
Piranshahr
Average
2
1.5 ± 0.23
3.0 ± 1.04
0.6 ± 0.29
0.5 ± 0.24
–
–
1.7 ± 0.59
1.3 ± 0.57
Baneh
2
7.3 ± 0.98
1.5 ± 0.23
1.6 ± 0.65
1.4 ± 0.38
Farsan
2
6.3 ± 1.46
1.3 ± 0.39
1.4 ± 0.19
1.2 ± 0.38
Saman
2
5.3 ± 0.79
1.4 ± 0.26
1.0 ± 0.26
0.7 ± 0.24
Shahrekord
3
4.3 ± 1.70
1.0 ± 0.28
0.9 ± 0.66
1.1 ± 0.41
5.6 ± 1.8
1.3 ± 0.42
1.2 ± 0.71
1.1 ± 0.53
Bazoft
3
1.5 ± 0.36
0.4 ± 0.05
0.3 ± 0.10
0.9 ± 0.27
Boroojen
5
3.4 ± 0.40
0.6 ± 0.30
0.2 ± 0.20
0.9 ± 0.43
Jooneghan
4
2.8 ± 0.55
0.7 ± 0.19
0.1 ± 0.12
0.9 ± 0.15
Mianjangale station 2
3.8 ± 1.18
0.6 ± 0.42
1.2 ± 0.24
1.0 ± 0.42
Mountain’s Saman
4
3.3 ± 0.38
0.5 ± 0.29
0.2 ± 0.10
1.1 ± 0.50
3.0 ± 1.01
0.6 ± 0.46
0.3 ± 0.22
1.0 ± 0.67
2
9.3 ± 1.20
1.8 ± 0.69
1.7 ± 0.42
1.4 ± 0.25
Average
P. elaeagnifolia
Average
P. fenzliana
Marand
Mianjangale station 1
8.0 ± 1.25
2.0 ± 0.48
1.5 ± 0.57
1.3 ± 0.23
Average
8.4 ± 1.45
1.9 ± 0.68
1.5 ± 0.57
1.3 ± 0.28
P. korschinskyi
Mianjangale station 2
Oroomeih
3
4.4 ± 1.74
3.9 ± 0.55
1.5 ± 0.25
1.3 ± 0.39
P. kotschyi
Baneh
Average
P. orientalis
1.3 ± 0.27
0.9 ± 0.22
4.2 ± 1.89
1.4 ± 0.49
–
1.1 ± 0.38
3
4.2 ± 0.98
0.5 ± 0.30
–
1.3 ± 0.22
Mianjangale station 2
3.5 ± 0.66
0.9 ± 0.44
–
0.6 ± 0.30
Average
3.7 ± 1.30
0.7 ± 0.59
–
0.8 ± 0.41
Ardal
3
1.3 ± 0.67
0.4 ± 0.29
0.2 ± 0.05
0.9 ± 0.50
Baneh
2
1.8 ± 0.71
0.5 ± 0.20
0.3 ± 0.03
1.0 ± 0.42
Kareh-e- Base
4
1.3 ± 0.10
0.4 ± 0.10
0.1 ± 0.10
0.9 ± 0.11
Lordegan
2
1.4 ± 0.46
0.5 ± 0.16
0.1 ± 0.46
1.3 ± 0.48
Mountain’s Saman
3
Average
P. trichamygdalus Mianjangale station 3
1.4 ± 0.36
0.6 ± 0.29
0.2 ± 0.06
0.9 ± 0.26
1.4 ± 0.73
0.5 ± 0.34
0.2 ± 0.01
1.0 ± 0.5
4.4 ± 1.37
3.1 ± 0.62
0.5 ± 0.25
0.9 ± 0.27
2
3.9 ± 0.55
2.9 ± 0.38
0.4 ± 0.05
0.9 ± 0.15
Average
4.2 ± 1.53
3.0 ± 0.82
0.5 ± 0.25
P. eburnea
Baneh
2
Mianjangale station 2
1.0 ± 0.62
1.4 ± 0.36
0.4 ± 0.55
0.3 ± 0.76
P. erioclada
Mountain’s Saman
Sardasht
Lycioides
Spartioides
–
–
Average
P. lycioides
1
–
–
0.9 ± 0.34
0.8 ± 0.19
0.9 ± 0.22
1.2 ± 0.73
0.4 ± 0.94
–
0.8 ± 0.28
0.9 ± 0.50
0.6 ± 0.29
–
0.8 ± 0.50
Mianjangale station 3
0.9 ± 0.26
0.4 ± 0.10
–
0.9 ± 0.27
Average
0.9 ± 0.37
0.5 ± 0.23
–
0.9 ± 0.48
2.8 ± 1.35
0.5 ± 0.26
–
0.9 ± 0.22
Bazoft
2
Kareh-e- Base
3
3.1 ± 0.88
0.8 ± 0.50
–
0.9 ± 0.43
Lordegan
2
3.2 ± 0.38
0.9 ± 0.86
–
0.9 ± 0.50
Mianjangale station 2
2.6 ± 0.50
0.5 ± 0.30
–
1.3 ± 0.64
Oroomeih
2.8 ± 0.26
1.0 ± 0.86
–
1.0 ± 0.42
2.9 ± 1.01
0.8 ± 0.85
–
1.0 ± 0.67
Average
3
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952
Genet Resour Crop Evol (2009) 56:947–961
Table 2 continued
Section
Species
P. reuteri
P. urumiensis
Location of
population
No of
accessions
P. pabotii
2
3.1 ± 0.48
0.5 ± 0.05
–
0.9 ± 0.11
2.3 ± 0.11
2.7 ± 0.41
0.6 ± 0.29
0.6 ± 0.24
–
–
0.9 ± 0.58
0.9 ± 0.48
Oroomeih
3
2.5 ± 0.76
0.7 ± 0.19
0.5 ± 0.27
1.4 ± 0.38
Salmas
2
2.1 ± 0.55
0.6 ± 0.29
1.0 ± 0.40
1.7 ± 0.59
2.3 ± 1.04
0.7 ± 0.36
0.5 ± 0.32
1.5 ± 0.74
2
4.0 ± 0.98
1.3 ± 0.26
1.0 ± 0.41
0.7 ± 0.25
Dasht-e- Khan mirza
Felard
2
4.3 ± 1.71
1.2 ± 0.21
0.9 ± 0.50
1.1 ± 0.39
Sardasht
2
5.50 ± 0.72
1.7 ± 0.30
1.3 ± 0.68
1.4 ± 0.56
1.1 ± 0.56
4.6 ± 1.56
1.4 ± 0.35
1.1 ± 0.74
Boroojen
2
1.9 ± 0.67
0.3 ± 0.22
0.5 ± 0.06
0.9 ± 0.22
Lordegan
2
3.3 ± 1.35
1.3 ± 0.26
0.7 ± 0.17
0.6 ± 0.76
Kareh-e- Base
3
2.5 ± 0.79
1.2 ± 0.40
0.5 ± 0.27
0.8 ± 0.31
Mianjangale station
2
2.8 ± 0.80
1.0 ± 0.28
0.3 ± 0.22
1.3 ± 0.27
2.5 ± 1.32
1.0 ± 0.36
0.5 ± 0.27
0.9 ± 0.69
Boroojen
2
2.0 ± 0.76
0.4 ± 0.05
–
0.9 ± 0.27
Koohrang
2
2.5 ± 0.76
0.6 ± 0.29
–
0.9 ± 0.32
Lordegan
Average
3
1.9 ± 0.67
2.1 ± 1.13
0.5 ± 0.16
0.5 ± 0.25
–
–
0.8 ± 0.30
0.9 ± 0.44
Mahabad
2
4.4 ± 1.74
1.4 ± 0.23
0.2 ± 0.06
1.0 ± 0.42
Sardasht
2
2.5 ± 0.76
0.6 ± 0.20
0.3 ± 0.22
0.9 ± 0.11
3.5 ± 1.75
1.0 ± 0.36
0.3 ± 0.20
0.9 ± 0.37
5.0 ± 0.70
1.2 ± 0.26
1.0 ± 0.30
0.7 ± 0.26
Average
P. scoparia
Internode length
(cm)
2
Average
P. haussknechtii
Petiole length
(cm)
Lordegan
Average
P. glauca
Leaf width
(cm)
Kareh-e- Base
Average
Average
P. arabica
Leaf length
(cm)
Boroojen
3
Felard
2
6.1 ± 0.98
1.5 ± 0.40
1.2 ± 0.21
1.5 ± 0.36
Kareh-e- Base
3
4.2 ± 1.49
1.2 ± 0.30
1.3 ± 0.70
1.0 ± 0.26
Lordegan
3
6.3 ± 1.50
1.3 ± 0.22
1.0 ± 0.40
1.3 ± 0.38
Mianjangale station
2
4.0 ± 0.79
1.0 ± 0.28
1.0 ± 0.30
1.4 ± 0.24
Mountain’s Saman
5
Average
4.4 ± 1.70
1.0 ± 0.23
0.9 ± 0.60
1.2 ± 0.40
5.0 ± 2.0
1.2 ± 0.46
1.1 ± 0.78
1.2 ± 0.54
Average values and standard deviation
the largest leaf sizes. Leaf margins were entire in all
locations except those in Jooneghan and Boroojen.
However, P. fenzliana accessions from the locations
of Marand and Mianjangale did not differ significantly in leaf sizes. Within P. fenzliana, leaf shapes
ranged from oblong and elliptical to oval. Leaf traits
of P. korschinskyi characterized in this study corresponded to those reported previously by Shalaby
et al. (1997) and Talhouk et al. (2000). Leaf margins
were crenate in all accessions, while leaf apices were
obtuse in all locations except in Mianjangale which
had both crenate and entire leaves. In addition, while
123
the accessions were generally spineless, some were
spinescent. Within P. kotschyi, accessions from
Baneh had greater average leaf sizes than drier
location. Three leaf shapes were observed in P.
orientalis (Fig. 2), obovate, elliptical and lenticular,
with entire margins and obtuse leaf apices corresponding to previous reports (Mouterde 1996; Post
and Dinsmore 1932). While, all of the P.
trichamygdalus accessions had elliptical leaf shapes.
Within section Lycioides, leaf traits of P. eburnea
were obovate and leaf margins were both crenate and
oblance in all locations as previously reported by
Genet Resour Crop Evol (2009) 56:947–961
953
Fig. 2 Detail of leaf and
fruit of wild almond species
from Iran P. elaeagnifolia
(A) and P. orientalis
(B) (section Euamygdalus),
P. eburnea (C) (section
Lycioides), and P. arabica
(D) (section Spartioides)
Safaei (1999). In addition, the accessions were
spinescent (Fig. 2). P. erioclada, accessions in the
two sited studied (Saman and Mianjangale) did not
have significantly different leaf sizes, and had similar
annual rainfall. P. lycioides accessions in the Lordegan, which receives the highest annual rainfall
of 567.3 mm/yr, had the greatest average leaf sizes.
P. lycioides was spinescent and had leaf shapes that
were linear-lanceolate and leaf margins that were
crenate in all accessions as reported by Etemadi and
Asadi (1999). P. reuteri, which is distributed in
central and southern Iran, had leaf shapes that were
linear lanceolate and leaf margins that were crenate.
Within P. urumiensis, leaf shapes varied from
lanceolate to ovate-lanceolate.
Within the more distinct section Spartioides,
P. arabica (Fig. 2) accessions from Sardasht had greater
leaf sizes, which ranged from linear to linear-lanceolate, than Felard or Dasht-e-khan mirza. Accessions
of P. glauca from Lordegan had the greatest leaf sizes,
including leaf length, leaf width and petiole length,
when compared accessions from n Boroojen, Mal-ekhalefeh and Mianjangale. P. haussknechtii accessions from the Koohrang, which receives very high
annual rainfall levels of 1441.8 mm/yr, have greater
leaf sizes than other locations. Leaf traits of P.
haussknechtii as characterized in this study
corresponded to those reported by Etemadi and Asadi
(1999) and Moradi (2005). Leaf shapes in P. pabotii,
were oblong-elliptical and leaf margins were entire in
most accessions. As observed for other species, P.
scoparia accessions from Lordegan, which receives
annual rainfall of 567.3 mm/yr, had greater average
leaf length, leaf width, and petiole length than those in
the drier zones.
Fruit traits
Nut weigh varied widely between the heaviest species
(P. communis, 5.1 g on average) to the lightest one
(P. eburnea, 0.5 g), while kernel weigh ranged
between 2.0 g (P. korschinskyi) and 0.3 (P. trichamygdalus and P. haussknechtii) (Table 3). Nut
width and length range was similar to nut weigh
range in most species. Shell thickness ranged
between 2.9 mm (P. communis) and 0.2 mm (P.
reuteri). Unlike leaf traits, fruit dimensions did not
appear associated with either rainfall or elevation,
suggesting the high degree of homoplasy described in
Prunus by Bortiri et al. (2006). Homoplasy occurs
when characters are similar but are not derived from a
common ancestor.
Within the section Euamygdalus, all P. carduchorum accessions showed small nuts and kernel with a
123
954
Genet Resour Crop Evol (2009) 56:947–961
Table 3 Evaluation of fruit (nut) traits in the wild almond species studied
Section
Species
Euamygdalus P. carduchorum
Location of
population
Nut
No of
accessions weight
(g)
2
0.6 ± 0.1
13.2 ± 1.0
16.3 ± 4.2
0.2 ± 0.1 0.4 ± 0.1
0.7 ± 0.5
10.2 ± 1.1
14.5 ± 5.2
0.3 ± 0.1 0.6 ± 0.2
0.6 ± 0.4
12.0 ± 1.4
15.4 ± 7.0
0.3 ± 0.1 0.5 ± 0.2
Baneh
2
4.6 ± 0.3
23.4 ± 0.5
30.2 ± 1.9
3.2 ± 0.8 1.5 ± 0.7
Farsan
2
4.8 ± 1.2
17.0 ± 1.0
31.2 ± 1.9
3.0 ± 0.8 1.2 ± 0.4
Saman
2
5.4 ± 0.7
22.2 ± 1.7
41.6 ± 5.6
2.2 ± 0.5 1.8 ± 0.7
Shahrekord
3
5.5 ± 0.8
23.8 ± 1.1
30.7 ± 1.5
3.1 ± 0.1 1.1 ± 0.1
5.1 ± 1.13 21.8 ± 1.6
33.1 ± 3.9
2.9 ± 0.7 1.4 ± 0.7
Bazoft
3
0.5 ± 0.2
9.6 ± 1.0
23.3 ± 1.8
2.1 ± 0.2 0.4 ± 0.6
Boroojen
5
1.3 ± 0.6
15.5 ± 2.3
19.3 ± 2.8
1.3 ± 0.3 1.2 ± 0.2
Jooneghan
4
2.1 ± 0.4
6.5 ± 2.1
16.3 ± 5.2
1.5 ± 0.5 0.4 ± 0.0
Mianjangale
station
2
0.6 ± 0.3
12.3 ± 2.4
22.1 ± 1.0
0.7 ± 0.2 0.4 ± 0.6
Mountain’s Saman 4
2.5 ± 0.6
9.4 ± 1.8
18.0 ± 1.0
0.3 ± 0.4 0.4 ± 0.0
1.3 ± 0.8
11.0 ± 3.6
19.3 ± 4.6
1.2 ± 0.6 0.8 ± 0.5
Marand
2
1.5 ± 0.2
16.9 ± 2.4
24.1 ± 1.0
1.3 ± 0.1 1.2 ± 0.2
Mianjangale
station
1
0.6 ± 0.3
15.1 ± 0.5
23.2 ± 0.4
0.3 ± 0.7 0.3 ± 0.0
Average
P. korschinskyi
Mianjangale
station
2
Oroomeih
3
Average
P. kotschyi
Baneh
P. trichamygdalus
P. eburnea
P. erioclada
23.5 ± 0.8
0.6 ± 0.5 0.6 ± 0.1
18.3 ± 0.5
23.4 ± 0.3
2.6 ± 0.3 2.3 ± 0.1
3.4 ± 0.2
16.2 ± 0.6
27.0 ± 1.2
2.2 ± 0.2 1.7 ± 0.5
4.0 ± 0.3
17.0 ± 1.8
26.0 ± 1.2
2.4 ± 0.4 2.0 ± 0.5
0.9 ± 0.5
9.6 ± 2.1
14.5 ± 1.2
1.3 ± 0.1 1.3 ± 0.2
1.5 ± 0.3
9.8 ± 1.8
15.8 ± 2.8
1.2 ± 0.0 1.2 ± 0.0
1.1 ± 0.6
9.7 ± 3.1
15.0 ± 3.0
1.3 ± 0.1 1.3 ± 0.2
Ardal
3
0.6 ± 0.3
8.4 ± 0.5
17.0 ± 0.2
1.2 ± 1.3 0.5 ± 0.2
Baneh
2
0.6 ± 0.1
10.4 ± 1.1
14.4 ± 5.2
0.7 ± 0.2 0.3 ± 0.2
Kareh-e- Base
4
0.4 ± 0.5
9.3 ± 1.0
13.4 ± 0.8
0.3 ± 0.2 0.3 ± 0.2
Lordegan
2
2.1 ± 0.6
16.9 ± 2.4
23.2 ± 1.2
1.3 ± 0.3 1.2 ± 0.2
Mountain’s Saman 3
0.5 ± 0.2
9.8 ± 1.8
15.8 ± 2.8
0.3 ± 0.1 0.3 ± 0.0
Average
0.8 ± 0.6
10.4 ± 2.2
16.2 ± 1.8
0.7 ± 0.6 0.7 ± 0.3
0.8 ± 0.2
16.6 ± 1.5
22.7 ± 2.4
1.5 ± 0.0 0.4 ± 0.0
Mianjangale
station
3
Sardasht
2
2.1 ± 0.6
14.7 ± 0.7
23.2 ± 1.8
0.7 ± 0.2 0.2 ± 0.1
1.3 ± 0.5
15.8 ± 1.75 23.0 ± 3.3
1.2 ± 0.1 0.3 ± 0.1
Baneh
2
0.6 ± 0.5
10.2 ± 1.1
14.5 ± 5.2
1.5 ± 1.3 0.4 ± 0.3
Mianjangale
station
2
0.7 ± 0.2
9.3 ± 2.1
12.2 ± 1.2
0.4 ± 0.1 0.4 ± 0.2
Average
0.6 ± 0.5
9.7 ± 2.2
13.3 ± 4.5
1.0 ± 0.9 0.4 ± 0.4
Mountain’s Saman 1
0.6 ± 0.2
9.3 ± 2.1
10.2 ± 0.4
0.2 ± 0.1 0.7 ± 0.2
Mianjangale
station
0.6 ± 0.5
9.6 ± 2.4
14.5 ± 1.2
1.5 ± 1.3 0.2 ± 0.4
0.6 ± 0.5
9.5 ± 3.1
13.4 ± 1.25 1.2 ± 1.1 0.3 ± 0.4
Average
123
15.7 ± 1.5
4.5 ± 0.3
3
Average
Lycioides
0.9 ± 0.3
Mountain’s Saman 2
Average
P. orientalis
Kernel
weight
(g)
2
Average
P. fenzliana
Shell
thickness
(mm)
Mahabad
Average
P. elaeagnifolia
Length
(mm)
Piranshahr
Average
P. communis
Width
(mm)
3
Genet Resour Crop Evol (2009) 56:947–961
955
Table 3 continued
Section
Species
P. lycioides
Location of
population
Nut
No of
accessions weight
(g)
2
1.3 ± 0.6
9.6 ± 1.0 13.1 ± 1.0
1.5 ± 0.4
0.5 ± 0.1
2.1 ± 0.3 16.9 ± 2.4 22.1 ± 1.8
0.2 ± 0.3
1.2 ± 0.2
Lordegan
2
0.5 ± 0.2
9.8 ± 0.3 14.3 ± 2.8
1.3 ± 0.3
0.6 ± 0.0
Mianjangale station
2
0.6 ± 0.4 10.2 ± 1.1 10.0 ± 0.5
1.2 ± 0.6
0.4 ± 0.4
Oroomeih
3
0.6 ± 0.1 13.2 ± 0.7
0.2 ± 0.5
0.5 ± 0.3
1.3 ± 0.5 12.4 ± 1.7 14.1 ± 2.5
0.7 ± 0.6
0.8 ± 0.3
Lordegan
2
2.1 ± 0.6
9.6 ± 2.4 13.3 ± 1.8
0.2 ± 0.3
0.4 ± 0.2
Kareh-e- Base
2
0.5 ± 0.2
9.3 ± 1.5 10.0 ± 1.0
0.3 ± 0.1
0.3 ± 0.0
1.3 ± 0.6
9.4 ± 2.7 12.0 ± 2.0
0.2 ± 0.5
0.4 ± 0.1
0.5 ± 0.1 10.2 ± 1.1 14.5 ± 1.2
0.3 ± 0.2
0.4 ± 0.0
Oroomeih
3
Salmas
2
0.5 ± 0.1
0.5 ± 0.1
2.0 ± 0.5 12.1 ± 2.4 20.0 ± 1.7
1.2 ± 0.3
1.2 ± 0.3
2.2 ± 0.5 9.6 ± 1.5 15.8 ± 2.0
1.5 ± 0.5 10.2 ± 2.3 13.0 ± 2.0
0.2 ± 0.1
0.2 ± 1.3
0.4 ± 0.0
0.7 ± 0.4
2.0 ± 0.7 10.6 ± 3.0 16.3 ± 2.6
0.5 ± 0.8
0.7 ± 0.3
Boroojen
2
0.8 ± 0.1
9.3 ± 2.1 16.8 ± 0.5
0.2 ± 0.1
0.3 ± 0.1
Lordegan
2
2.1 ± 0.3 16.9 ± 1.8 15.3 ± 0.1
0.3 ± 0.1
0.4 ± 0.4
Kareh-e- Base
3
0.3 ± 0.5
9.6 ± 2.4 14.5 ± 1.8
1.3 ± 0.1
0.7 ± 0.2
Mianjangale station
2
0.5 ± 0.2 14.7 ± 0.7 17.0 ± 0.1
0.8 ± 0.3
0.3 ± 0.0
0.9 ± 0.4 12.3 ± 2.6 15.7 ± 1.0
0.7 ± 0.2
0.6 ± 0.3
Boroojen
2
0.4 ± 0.2 16.9 ± 2.4 19.3 ± 1.8
1.2 ± 0.0
0.3 ± 0.4
Koohrang
2
2.1 ± 0.6 15.2 ± 0.7 22.7 ± 2.4
0.7 ± 0.2
1.2 ± 0.1
Lordegan
3
0.5 ± 0.3
9.3 ± 2.1 27.2 ± 1.5
0.6 ± 0.3
0.3 ± 0.2
1.1 ± 0.6
9.5 ± 3.1 13.4 ± 1.25 1.2 ± 1.1
0.3 ± 0.4
Mahabad
2
Sardasht
2
Average
P. scoparia
1.2 ± 0.2
0.7 ± 0.3
2
2
Average
P. pabotii
9.3 ± 2.2 17.0 ± 1.0
1.0 ± 0.4 10.0 ± 2.5 15.5 ± 1.7
Dasht-e- Khan mirza 2
Average
P. haussknechtii
0.6 ± 0.5
9.3 ± 2.1
Felard
Sardasht
Average
P. glauca
Kernel
weight
(g)
3
Average
Spartioides P. arabica
Shell
thickness
(mm)
Bazoft
Average
P. urumiensis
Length
(mm)
Kareh-e- Base
Average
P. reuteri
Width
(mm)
0.6 ± 0.2 14.7 ± 0.2 23.2 ± 1.8
0.7 ± 0.4
0.4 ± 0.4
1.5 ± 0.4 16.9 ± 2.3 24.7 ± 2.4
0.7 ± 0.2
0.7 ± 0.2
1.0 ± 0.4 16.0 ± 2.0 24.0 ± 2.9
0.7 ± 0.4
0.8 ± 0.4
Boroojen
Felard
3
2
1.5 ± 0.6 10.2 ± 2.1 14.1 ± 1.2
2.1 ± 0.3 9.3 ± 0.4 10.1 ± 1.8
0.2 ± 1.3
0.7 ± 0.5
0.4 ± 0.1
0.5 ± 0.4
Kareh-e- Base
3
1.6 ± 0.5 10.2 ± 2.3 13.0 ± 2.0
0.7 ± 0.4
0.7 ± 0.1
Lordegan
3
2.3 ± 0.5 13.1 ± 2.4 23.1 ± 1.8
1.3 ± 0.3
1.2 ± 0.2
Mianjangale station
2
2.5 ± 0.6
8.4 ± 0.5 17.1 ± 1.0
0.2 ± 0.5
0.6 ± 0.2
Mountain’s Saman
5
2.1 ± 0.6
9.8 ± 1.8 15.8 ± 2.8
0.3 ± 0.1
0.3 ± 0.0
1.8 ± 0.8 10.3 ± 2.8 15.8 ± 3.1
0.5 ± 0.9
0.6 ± 0.3
Average
Average values and standard deviation
very thick shell. In P. communis, nut characters were
not significantly different among the provinces. P.
communis seedling populations had medium to hard
shells with well sealed sutures differing from P.
elaeagnifolia (Fig. 2) where nut length ranged from
18 to 23.3 mm and nut width from 6.5 to 15.5 mm
agreeing with previous reports of Safaei (1999)
Etemadi and Asadi (1999), and Sorkheh et al.
(2007). In P. fenzliana, nut characters were not
significantly different between the two location
123
956
studied. In P. korschinskyi, nut length and nut width
were larger than those reported in Syria (Shalaby
et al. 1997). While kernel weight of P. korschinskyi in
Syria was similar to average kernel weight reported
in this study. In P. kotschyi, fruit characters were not
variable among locations. For example, shell thickness in Saman was similar to Baneh. Within P.
orientalis (Fig. 2), fruit characters were more variable among locations with an average shell thickness
of accessions from Saman Mtn. and Kereh-e-Base
lower than accessions from Lordegan agreeing with
previous reports by Shalaby et al. (1997). In Iran, P.
orientalis is limited to arid and semi-arid regions and
elevations of 1,100–2,500 m (Gorttapeh et al. 2005).
In P. trichamygdalus, which is distributed only in
west Azerbaijan, the populations had medium to hard
shells and well sealed sutures.
In section Lycioides, P. eburnea (Fig. 2) had
average nut length ranging between 12.2 and
14.5 mm and nut width between 9.3 and 10.2 mm.
These results also correspond with those of Gorttapeh
et al. (2005) where average nut length ranged between
14.5 and 16.3 mm, while nut width ranged between
10.2 and 13.2 mm. In P. erioclada, fruit characters
were similar between the locations of Saman and
Mianjangale. Variation within P. lycioides, which was
found at relatively high elevations, was extensive in
agreement with Etemadi and Asadi (1999) and Safaei
(1999). In P. reuteri, average nut length ranged
between 10.0 and 13.3 mm, while nut width and shell
thickness remained relatively uniform.
Within the more distant section Spartioides, in the
case of P. arabica nut length ranged from 13 to
15.8 mm (Fig. 2). P. arabica is distributed in Iran at
elevations from 1,100 to 2,300 m (Moradi 2005). In
P. glauca, average of nut length ranged from 14.5 to
17.0 mm, nut width from 9.6 to 16.9 mm and kernel
weight from 0.3 to 0.8 gr. In addition, nut traits in P.
haussknechtii were significantly different between
locations with different annual rainfall levels. In P.
pabotii (possibly a species hybrid between P. carduchorum and P. haussknechtii), fruit characteristics
were variable among locations.
Diversity indices, principal component analysis
and correlation among leaf and fruit traits
In general, the diversity indices were similar in all
species ranging from 0.796 (P. fenzliana) and 0.487
123
Genet Resour Crop Evol (2009) 56:947–961
(P. reuteri) (Table 4). In addition, shell thickness
(0.610), and kernel weight (0.630) had lower diversity indices compared to the remaining traits. Results
indicated a high morphological diversity of wild
almond species in Iran. This result was expected
since almond is an outbreeder and spontaneous
hybridization is known to occur among species
(Serafinov 1971; Denisov 1988). This high phenotypic variability agree with previous reports in the
molecular characterization using different markers as
nuclear and chloroplast Simple sequence repeats
(SSRs) (Martı́nez-Gómez et al. 2003; Zeinalabedini
et al. 2008) or Amplified fragment length polymorphisms (AFLPs) (Sorkheh et al. 2007).
Principal component analysis revealed that in wild
almond species fruit traits were prevalent in the first
component and contributed most of total variation
(Table 5). The three components explained 80.1% of
the total variation contributed by all traits. The first
component contributed 46% of the variation where
kernel weight, nut weight, and nut width had highest
loadings. The second component accounted for 22%
of the total variation and featured leaf length, leaf
width, petiole length, internode’s length and shell
thickness while the third component accounted for
only 12% of the variation featuring internode length.
Nut traits such as nut weight, which were consistent
in their contributions to the first component in all
almond species populations, are thus useful for
almond germplasm characterization.
Leaf traits were consistently present in the second
component and therefore contributed less to the
variability. These results correspond to those of
Lansari et al. (1994) who used a similar analysis to
compare kernel, nut and leaf characters among
Moroccan almond clones and found the variables
contributing to leaf traits are less important in
explaining the variation among the selections than
nut and kernel characters. However, although leaf
traits were secondary in importance with respect to
their contribution to the overall variability, they have
been previously shown to play a more significant role
in characterizing the germplasm when plants are
subjected to stress (Lansari et al. 1994). Also, leaves
of certain species such as P. arabica and P. scoparia
drop in natural conditions after few weeks while the
green shoots continue photosynthesis, possibly being
a mechanism for tolerance against drought stress. Our
results also agree with those of Talhouk et al. (2000),
Section
Euamygdalus
Lycioides
Spartioides
Average
Species
Leaf
Petiole length
Intern. length
Nut weight
Width
Length
Shell thickness
Kernel weight
Average
Length
Width
P. carduchorum
0.725
0.665
–
0.730
0.785
0.780
0.840
0.480
–
0.672
P. communis
0.761
0.754
0.905
0.870
0.765
0.873
0.722
0.754
0.830
0.784
P. elaeagnifolia
0.850
0.740
0.670
0.850
0.954
0.535
0.785
0.680
0.956
0.771
P. fenzliana
0.928
0.725
0.875
0.875
0.956
0.955
0.796
0.410
0.951
0.796
P. korschinskyi
0.829
0.725
0.950
0.950
0.956
0.755
0.865
0.765
0.430
0.793
P. kotschyi
0.852
0.701
–
0.746
0.850
0.748
0.784
0.635
0.600
0.752
P. orientalis
0.834
0.845
0.509
0.558
0.546
0.763
0.835
0.410
0.453
0.645
P. trichamygdalus
P. eburnea
0.829
0.834
0.738
0.849
0.546
–
0.546
0.509
0.559
0.559
0.708
0.789
0.863
0.835
0.420
0.458
0.453
–
0.636
0.629
P. erioclada
0.625
0.750
–
–
0.680
0.626
0.753
0.758
0.410
0.644
P. lycioides
0.650
0.543
–
0.648
0.685
0.763
0.410
0.543
0.410
0.574
P. reuteri
0.410
0.451
–
0.365
0.451
0.559
0.654
0.573
0.350
0.487
P. urumiensis
0.850
0.701
0.709
0.703
0.644
0.745
0.853
0.445
0.778
0.661
P. arabica
0.730
0.740
0.604
0.648
0.546
0.673
0.748
0.525
0.450
0.620
P. glauca
0.736
0.679
0.564
0.564
0.549
0.673
0.738
0.530
0.578
0.642
P. haussknechtii
0.839
0.709
–
–
0.626
0.750
0.780
0.559
0.895
0.720
P. pabotii
0.780
0.640
0.605
0.730
0.745
0.830
0.750
0.453
0.630
0.678
P. scoparia
0.735
0.753
0.804
0.548
0.543
0.663
0.732
0.425
0.420
0.603
0.808
0.720
0.780
0.855
0.808
0.779
0.801
0.610
0.630
Genet Resour Crop Evol (2009) 56:947–961
Table 4 Diversity indices (hs.J) for quantitative leaf and fruit traits in the wild almond species evaluated
957
123
958
Genet Resour Crop Evol (2009) 56:947–961
Table 5 Correlation coefficients among the quantitative leaf
and fruit traits and the first 3 principal components in the wild
almond species evaluated
Variables
Components
1
2
3
Leaf length
0.315
0.802
0.050
Leaf width
0.221
0.800
0.174
Petiole length
0.340
0.793
-0.023
Internode length
0.280
-0.159
-0.840
Nut width
0.830
0.240
-0.350
Nut length
Nut weight
0.640
0.920
0.483
0.072
-0.263
-0.008
Shell thickness
0.283
0.807
0.044
0.982
-0.063
Kernel weight
Cumulative % of total variance
45.8
22.3
0.079
12
who used similar analysis and found that three
components explained 80% of the total variation in
P. orientalis and 66.7% for P. communis populations.
No significant correlation was found between leaf
and traits (Table 6). However, a correlation between
leaf length and width and petiole length was
observed. In addition, nut width was highly correlated
with nut weight, and kernel weight was significantly
correlated with nut weight and shell thickness. A
close relationship between traits could facilitate or
hinder gene introgression since strong selection for a
desirable trait, could favour the presence of another
desirable trait from this population (Dicenta and
Garcı́a 1992).
The observed differences among the wild species
evaluated suggest that despite high correlations
between some traits, it might not be feasible to fully
extrapolate information from one species to even other
closely related species. In this sense, Sánchez-Pérez
et al. (2007) described the absence of correlations
between most agronomic traits in almond. Only for few
tree and fruit traits were did the correlations show
Pearson Correlation Coefficient (r) higher than 0.5.
Agronomical traits and potential breeding use
All the species were found to be self-incompatible
and all seed were bitter or slightly bitter (Table 7).
Flowering and ripening dates were variable (from
early to very late) indicating differences in the
chilling requirements for flowering and differences
in the growth cycle resultant.
All related wild species as well as many cultivated
almonds express gametophytic self-incompatibility.
Gametophytic incompatibility prevents self-fertilization (Socias i company 1992), favours crosspollination (Weinbaum 1985), and maintains genetic
variability within seedling populations (Arulsekar
et al. 1989). This trait, while is a negative trait from
the agronomic point (Socias i Company 1992), would
have contributed to the variability that likely insured
the wide distribution and adaptation of these species.
In addition, native wild almond species predominantly
have bitter (or slightly bitter) kernel because of high
levels of the glucoside amygdaline, which hydrolizes
to benzaldehyde and cyanide when exposed to the
Table 6 Correlation among quantitative leaf and fruit traits in the wild almond species evaluated
Leaf
length
Leaf length
Leaf width
Leaf
width
Petiole
length
Internode
length
Nut
weight
Nut width Nut
length
0.876**
0.936**
0.800**
0.545
0.439
-0.057
0.108
-0.313
-0.275
0.445
-0.150
0.038
Petiole length
Internode
length
Nut weight
Nut width
Nut length
Shell
thickness
* Significant at the 0.05 probability level
** Significant at the 0.01 probability level
123
Shell
thickness
Kernel
weight
0.312
0.465
0.110
0.234
0.269
0.394
-0.32
0.078
-0.068
0.226
-0.072
0.274
0.048
0.246
0.279
0.768**
0.568*
0.717**
-0.283
0.435
0.825**
0.447
0.363
0.734**
Genet Resour Crop Evol (2009) 56:947–961
959
Table 7 Evaluation of agronomical traits in the wild almond species studied
Section
Species
Flowering date
Self-compatibility
Ripening date
Kernel taste
Euamygdalus
P. carduchorum
Very late
Self-incompatible
Late
Slightly bitter
P. communis
Middle
Self-incompatible
Middle
Bitter
P. elaeagnifolia
P. fenzliana
Very late
Early
Self-incompatible
Self-incompatible
Late
Middle
Bitter
Slightly bitter
P. korschinskyi
Early
Self-incompatible
Late
Bitter
P. kotschyi
Very late
Self-incompatible
Late
Bitter
P. orientalis
Middle
Self-incompatible
Late
Bitter
P. trichamygdalus
Early
Self-incompatible
Middle
Bitter
P. eburnea
Late
Self-incompatible
Middle
Bitter
P. erioclada
Middle
Self-incompatible
Late
Bitter
P. lycioides
Middle
Self-incompatible
Middle
Bitter
P. reuteri
Late
Self-incompatible
Late
Bitter
Lycioides
Spartioides
P. urumiensis
Middle
Self-incompatible
Early
Bitter
P. arabica
Late
Self-incompatible
Late
Slightly bitter
P. glauca
Very late
Self-incompatible
Late
Slightly bitter
P. haussknechtii
Middle
Self-incompatible
Middle
Slightly bitter
P. pabotii
Early
Self-incompatible
Middle
Bitter
P. scoparia
Very late
Self-incompatible
Late
Slightly bitter
enzyme emulsin (Conn 1980). This trait has adaptive
value by discouraging seed predation by birds and
mammals including human. Individuals producing
sweet kernels probably appear to have originated as
mutations with subsequent seedling segregation
within various Prunus species, including almond
peach and apricot (Bailey and Hough 1975).
The small kernel size common in these species is
undesirable in breeding programs, where high kernel
weight (approximately 1 g) is desired (Gradziel and
Kester 1998; Ledbetter and Shonnard 1992), although
for local production some of the accessions showed
relatively high kernel weight that resembled or even
exceeded kernel weights of local commercial cultivars (Etemadi and Asadi 1999; Moradi 2005). Our
results suggest that this germplasm is not a useful
source for the selection of larger nut and kernel size
with the possible exception of P. korschinskyi and P.
communis. However, wild almond populations in Iran
showed high variability in the other traits and
consequently could be considered as a potential
source of germplasm to be exploited in almond
improvement.
Many wild almond species have very small leaves
(especially in the Spartioides section), a probable
adaptation to the xerophytic conditions (less than
300 mm per year of rainfall). Lansari et al. (1994)
found that phenotypes collected from ‘‘native’’ seedling populations in Morocco tended to have smaller
leaves than introduced cultivars. P. scoparia has very
small leaves on long, slender shoots. These leaves tend
to abcise early in the season, with the green stems
continuing to photosynthesize, a characteristic that is
transmitted to the progeny. In this sense, Gentry (1956)
reported that P. spinosissima and P. spartioides
growing wild in Iran have been used by growers in
very arid conditions who top-work almond cultivars.
Development of drought resistant almonds production
systems, possibly utilizing native germplasm such as
P. scoparia, or P. spartioides would allow a more
sustainable production, particularly in more marginal
areas. Since the leaves of P. scoparia and its close
relatives typically drop in early summer, these species
may be better suited as rootstock material. Other more
cultivated almond-like species such P. arabica
(Denisov 1988) or P. fenzliana (Browicz and Zohary
1996) may also contribute drought resistance without
major changes in plant development patterns.
Frost resistance is a major breeding goal in many
production areas owing to cultivated almond’s very
123
960
early flowering time during late winter and early
spring. The possibility of use of related species with
a very late flowering date (high chilling requirements), as P. carduchorum, P. elaeagnifolia, P.
kotschyi, P. glauca or P. scoparia to develop new
varieties with delayed flowering would not only
reduce frost damage, but reduce disease damage if
flowering were delayed beyond the rainy season, and
would allow more efficient use of increasingly scarce
insect pollinators (Rickter 1972). The use P. elaeagnifolia to impart late-blooming has been also
reported in almond breeding programs (Sorkheh
et al. 2007).
Hard shells with well sealed sutures are reported
to be more resistant to insect and fungus infestation
while open sutures are highly susceptible to insect
and fungus damages (Ledbetter and Shonnard 1992;
Gradziel and Martı́nez-Gómez 2002). The use as a
source of insect and fungus resistance of related wild
species with very well sealed shell (i.e. species from
Spartioides section) (Fig. 2) offers breeding opportunities not readily available in more traditional
germplasm. In this sense, we have to note the
absence of resistance to fungus as Aspergillus flavus
in the cultivated almond varieties (Dicenta et al.
2003). Related species can also be used as a source
of less immediate breeding needs such as more
compact growth habit form (P. fenzliana, P. orientalis or P. scoparia) or early crop maturity in P.
urumiensis.
Current findings support these opportunities since
the phenotypic variability in Iranian native almond
has been found to be very high, suggesting an
extensive genetic diversity available to almond
cultivar and rootstock development programs. While
self-incompatibility, bitter kernel taste and small fruit
size are represent undesirable cultivar characteristics
and so represent impediments to the full utilization of
this germplasm, ongoing genetic improvement efforts
have shown that these traits are controlled by few
genes which are readily eliminated in the breeding
process (Martı́nez-Gómez et al. 2007).
Acknowledgements The authors offer grateful thanks to
Shahrekord University for financial assistance, as well as to the
Agriculture and Natural Resources Research Center of
Shahrekord, and to the Karj collection for access to trees.
Thanks are also due to Dr. Ali Vezvaei for helpful comments
on an earlier draft of the manuscript and H. Hakimei for
information assistance.
123
Genet Resour Crop Evol (2009) 56:947–961
References
Arulsekar S, Parfitt DE, Kester DE (1989) Comparison of
isozyme variability in peach and almond cultivars. J
Hered 77:272–274
Bailey CH, Hough LF (1975) Apricots. In: Janick J, Moore JN
(eds) Advances in fruit breeding. Purdue University Press,
West Lafayette, IN, pp 367–385
Bernhard R (1949) The peach-almond and its utilization. Rev
Horticole 121:97–101
Bortiri PE, Heuvel BV, Potter D (2006) Phylogenetic analysis
of morphology in Prunus reveals extensive homoplasy.
Plant Syst Evol 259:53–71. doi:10.1007/s00606-0060427-8
Browicz K (1969) Amygdalus L. In: Rechinger KH (ed) Flora
Iranica, vol 66. pp 166–168
Browicz K, Zohary D (1996) The genus Amygdalus L.
(Rosaceae): species relationships, distribution and evolution under domestication. Genet Resour Crop Evol
43:229–247. doi:10.1007/BF00123275
Conn EE (1980) Cyanogenic compounds. Annu Rev Plant
Physiol 31:433–451. doi:10.1146/annurev.pp.31.060180.
002245
Denisov VP (1980) Drought resistance of some almond species
in Turkmenistan. Trudy Prikladnot Bot Genet Selk
67:129–135
Denisov VP (1988) Almond Genetic Resources in the USSR
and their use in production and breeding. Acta Hortic
224:299–306
Dicenta F, Garcı́a JE (1992) Phenotypical correlations among
some traits in almond. J Genet Breed 46:241–246
Dicenta F, Martı́nez-Gómez P, Martı́nez-Pato E, Gradziel TM
(2003) Screening for Asperguillus flavus resistance in
almond. HortScience 38:266–268
Dimitrovski T, Ristevski B (1973) Ispitivanje podonosti divijeg
Badena Amygdalus webbii Sprach. Yugosl. Vocarstvo
Brez. 23:15–21 (Turkish)
Etemadi N, Asadi E (1999) Study the wild species of almond
and their distribution in Chaharmahal Bakhtiari province.
In: Proceedings First National Conference on Almond.
Shahrekord (IRAN), 24–27 August
Evreinoff VA (1952) Quelques observations biologiques sur
l’amandier. Rev Int Bot App Agr Trop 32:442–459
Felipe AJ (1975) F1 hybrids of peach and almond trees as a
model for both species. Agricultura 44:661–663
Felipe AJ (1984) Etat de l’arboretum des espèces sauvages
d’amandier a Saragose. Options méditerranéennes. 84/I:
203–204
Felipe AJ, Socias i Company R (1977) Un amandier sauvage,
probablement A. webbii, non encore mentionne en Espagne. In: 3d Coll. GREMP, CHEAM, Bari, Italy. pp 78–79
Gentry HS (1956) Almond culture in southern Iran. Almond
Facts 21:6–7
Ghahreman A, Attar F (1999) Biodiversity of plant species in
Iran, vol 1. Publication of Tehran University, Tehran
Gorttapeh AH, Hasani MH, Ranji H (2005) Recognition and
ecological investigation of almond species (Amygdalus
spp.) in West Azerbaijan province. IV International
Symposium on Pistachios & Almonds. Tehran (IRAN),
22–25 May
Genet Resour Crop Evol (2009) 56:947–961
Gradziel TM, Kester DE (1998) Breeding for self-fertility in
California almond cultivars. Acta Hortic 470:109–117
Gradziel TM, Martı́nez-Gómez P (2002) Shell seal breakdown
in almond is associated with the site of secondary ovule
abortion. J Am Soc Hortic Sci 127:69–74
Gradziel TM, Martı́nez-Gómez P, Dicenta F, Kester DE (2001)
The utilization of Prunus species for almond variety
improvement. J Am Pomol Soc 55:100–108
Grasselly C (1976a) Les espèces sauvages d’amandier. Options
Mediterr 32:28–44
Grasselly C (1976b) Origine et evolution de l’amandier cultive.
Options Mediterr 32:45–49
Grasselly C (1992) Considerazioni sulle caratteistique di alcune specie selvatiche di mandorlo e sulle loro possibilita
di utilizzazione in programmi di miglioramento genetico.
Progr. de recherche Agrimed. Nimes (France), June, 1990.
pp 135–144
Gulcan R (ed) (1985) Descriptor list for almond (Amygdalus
amygdalus). (Revised Edn.). International Board for Plant
Genetic Resources, Rome
Hutchenson CC (1970) A test for comparing diversities based
on Shannon formula. J Theor Biol 29:151–154. doi:
10.1016/0022-5193(70)90124-4
Jadrov DA (1970) Porte-Greffes de l’amandier. Sadovostvo
11:32
Kester DE, Gradziel TM (1996) Almonds. In: Janick J, Moore
JN (eds) Fruit breeding. Wiley, New York, USA, pp 1–97
Kester DE, Hansen CJ (1966) Rootstock potentialities of F1
hybrids between peach (Prunus persica L.) and almond
(Prunus amygdalus Batsch.). J Am Soc Hortic Sci
89:100–109
Kester DE, Gradziel TM, Grasselly C (1991) Almonds (Prunus). In: Moore JM, Ballington JR (eds) Genetic resources
of temperate fruit and nut crops. The International Society
for Horticultural Science, Wageningen, The Netherlands,
pp 701–758
Komarov VL, Shiskin BK, Yuzepchuk SV (eds) (1941) Flora
of the USSR, Vol.10: Rosaceae- Rosoideae, Prunoideae
(translated from the Russian, 1971). Israel Program for
Scientific Translation, Jerusalem
Ladizinsky G (1999) On the origin of almond. J Genet Resour
Crop Evol 46:143–147. doi:10.1023/A:1008690409554
Lansari A, Lessoni AF, Kester DE (1994) Morphological
variation within collections of Moroccan and almond
clones and Mediterranean cultivars. Euphytica 78:27–41
Ledbetter CA, Shonnard CB (1992) Evaluation of selected
almond (Prunus dulcis (Miller) D.A. Webb) germplasm
for several shell and kernel characteristics. Fruit Var J
46:79–82
Martı́nez-Gómez P, Arulsekar S, Potter D, Gradziel TM (2003)
Relationships among peach and almond and related species detected by SSR markers. J Am Soc Hortic Sci
128:667–671
Martı́nez-Gómez P, Sánchez-Pérez R, Dicenta F, Howad W,
Arus P, Gradziel TM (2007) Almonds. In: Kole CR (ed)
Genome mapping and molecular breeding. vol 4. Fruits &
Nuts. Springer. Heidelberg, Berlin, New York, Tokio. pp
229–242
961
Moradi M (2005) Identification and collection of almond
species and germplasm in the Chaharmahal va Bakhtiari
province. In: IV International Symposium on Pistachios &
almonds. Tehran (IRAN), 22–25 May
Mouterde P (1996) Nouv Flore Liban Syria, vol 1. Edition de
L’imprimeric Catholique, Beirut, Lebanon, p 563
Post GE, Dinsmore JE (1932) Flora of Syria, Palestine, and
Sinai, vol 1, 2nd edn. Publications of Faculty of Arts and
Sciences, American University of Beirut, Lebanon, p 658
Rickter AA (1972) L’amandier. Academie Sciences Agricoles.
Jardin Botanique de Nikits, Yalta
Safaei H (1999) Collecting, planting and investigation of wild
almond species characteristics in Fars province. In: Proceedings of the First National Conference on Almond.
Shahrekord (IRAN), 24–27 August 24–27
Sánchez-Pérez R, Ortega E, Duval H, Martı́nez-Gómez P,
Dicenta F (2007) Inheritance and relationships of important agronomic traits in almond. Euphytica 93:39–44
Serafinov S (1971) A spontaneous hybrid of Amygdalus
kuramica Korsh. and A. spinosissima Bge. from Afghanistan. Compt Rend Acad Sci Agric Bulgaricae 4:349–351
Shalaby MN, Ghazal AA, El-Rayes R, Aswad NG (1997)
Preliminary ecological and geobotanical investigation on
wild species of almond (Amygdalus L.) in Syria. IPGRL
Socias i Company R (1992) Breeding self-fertile almonds.
Plant Breeding Rev 8:313–338
Socias i Company R (1998) La taxonomie de l’amandier.
Options Méditerr 33:91–94
Socias i Company R, Felipe AJ (1992) Almond: A diverse
Germplasm. HortScience 27(7):718–863
Sorkheh K, Shiran B, Gradziel TM, Epperson BK, Martı́nezGómez P, Asadi E (2007) Amplified fragment length
polymorphism as a tool for molecular characterization of
almond germplasm: genetic diversity among cultivated
genotypes and related wild species of almond, and relationships with agronomic traits. Euphytica 156:327–344.
doi:10.1007/s10681-007-9382-x
Talhouk SN, Lubani RT, Baalbaki R, Zurayk R, Alkhatib A,
Parmaksizian L, Jaradat AA (2000) Phenotypic diversity
and morphological characterization of Amygdalus L.
species in Lebanon. Genet Resour Crop Evol 47:93–104.
doi:10.1023/A:1008763021129
Vlasic A (1977) L’amygdalus webbi Spach ed I suolsi ibridi
col pesco com portaninnesto del mandorlo. 3d Colloque
GREMPA, Bari, Italy. pp 80–81
Weinbaum SA (1985) Role of natural self-pollination in
self-fruitfulness in almond. Sci Hortic (Amsterdam)
27(3/4):295–302. doi:10.1016/0304-4238(85)90034-2
Zeinalabedini M, Majourhat K, Khayam-Nekoui M, Grigorian
V, Torchi M, Dicenta F, Martı́nez-Gómez P (2008)
Comparison of the use of morphological, protein and
DNA markers in the genetic characterization of Iranian
wild Prunus species. Sci Hortic (Amsterdam) 116:80–88.
doi:10.1016/j.scienta.2007.10.022
Zohary D (1983) Wild genetic resources of crops in Israel. Isr J
Bot 32:97–127
Zohary D (1998) Taxonomy of the almonds. Nucis 7:5–6
123
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