Not much is known in Israel about Quercus boissieri Reut. because it is only an associated species within the Quercus calliprinos-Pistacia palestine association of the Mediterranean sclerophyllous broad-leaf forests. Q. boissieri is a winter deciduous species that has sort of continental ecological requirements. It belongs to the eastern continental floral elements in Israel, where its occurrence represents the southernmost fringe of its global distribution in the Middle East. The species grows on the Golan Heights, the Galilee, the Carmel Range, and in Samaria and Judea.

Analysis of genetic diversity within and the differentiation among 14 populations that are assumed to be natural relicts was done by means of Random Amplified Polymorphic DNA analysis, using 20 primers that produced 32 polymorphic loci. The overall total genetic diversity (Ht) was 0.398, the overall within-population diversity (Hs) was 0.335, and the overall proportion of total diversity stemming from differences between populations (Gst) was 0.162. No relations could be established between the genetic and the geographic parameters.

The small genetic distances or the high identity between populations on the one hand, and the lack of aggregations or relatedness to geographic parameters on the other hand, give rise to the hypothesis that all the populations analyzed are remnants of a larger population that existed during the last glaciations. The period of warming since then, the fragmentation of the populations into sites differing in their ecological set-up, and human activity did not give rise to significant genetic differentiation among them.

Inference from these results suggests that plantations for acorn production, as propagation material for reforestation, should include the best phenotypes selected from all the relict populations regardless of ecological-geographical boundaries.

In: Israel Journal of Plant Sciences

We studied the effects of different environmental conditions on morphological and genetic variations in the Mediterranean geophyte Asphodelus aestivus in Israel. The study included six populations, ranging from mesic Mediterranean to arid ecosystems. The results showed important differential morphological traits in one population of the Mediterranean ecosystem (M1). They included longer leaves, longer inflorescences-stalks, and larger number of flower buds than those found among the other populations. We used RAPD analysis to get a genetic profile for all studied populations: 30 loci revealed by the use of 11 primers were studied on 30 plants from each study site. No unique allele was found. Nevertheless, the MI population was always different from the others in several molecular markers, and even created a different clade on the phylogenetic tree. Abiotic factors were considered to have caused the differentiation of the M1 population. A contingency χ2 test for heterogeneity of RAPD frequencies across all locations revealed significant differences in 17 RAPD loci (57%). The estimated genetic diversity within populations was 0.287 according to Nei's gene diversity and 0.432 according to Shannon's genetic diversity index. Differentiation among six populations of the RAPD loci (GST) ranged from 0.014 to 0.354 with a mean of 0.096. Principal coordinate analysis indicated the presence of genetically distinct sub-regional groups. Genetic and geographical distances among A. aestivus populations along the environmental gradient were found to be correlated, with the exception of the M1 population. In the present study, levels of gene variability within populations were higher than those between populations. Nevertheless, if we discard the unique M1 population, a clear genetic pattern linked to aridity and geographical distance was discerned.

In: Israel Journal of Plant Sciences

Phenological observations have shown that about 10 to 15 percent of the Quercus ithaburensis Decne (Tabor oak) trees in any given population shed their leaves very late in the season, and that this phenomenon is a characteristic of the individual trees, irrespective of meteorological factors. The aim of this study was to elucidate whether phenological differences in the leaf shedding behavior of Q. ithaburensis trees are also genotypic. DNA, extracted from one-year-old leaves sampled from trees shedding late in the season, was subjected to RAPD-based PCR procedure using 20 primers. Comparisons between allele frequencies in the 16 natural populations and the "late in season leaf-shedding" population revealed large differences in 3 out of the 72 loci analyzed.

In: Israel Journal of Plant Sciences

Analysis of the genetic diversity within and differentiation among 24 spontaneous occurrences of Q. calliprimnos in Israel (22) and Jordan (2) was done by means of Random Amplified Polymorphic DNA analysis (RAPD) with 10 primers that produced 23 detectable DNA fragments (alleles).

The results revealed that the overall total genetic diversity for the species (Ht) was 0.354, the overall within-population diversity (Hs) was 0.325, and the overall proportion of differences between populations (Gst) was 0.081. The Um Reichan population had the lowest and the Dir Razach population the highest within-population gene diversity. Small but significant differentiation between the main geographic regions in Israel was found.

Comparisons between populations revealed that, on average, each population of the 24 that were analyzed differed significantly from 13 ± 5 populations randomly distributed in the country. Three populations, Park Goren, Tzafririm, and Dir Razach, differed significantly from most or all of the other populations analyzed, whereas the Park Ha'Sharon, Mt. Amiad, and Beit Ha'Emeq populations were similar to most of the populations.

In: Israel Journal of Plant Sciences

Forest trees possess high genetic diversity and high heterozygosity which allow adaptation to changing environmental conditions. There is a tendency to propagate successful and unique genotypes, which are identified at their mature stage in the forests, for future improvement programs and conservation purposes. However, vegetative propagation of mature forest trees is still a challenge in many conifers. In this study, we focused on improving the rooting of cuttings of mature and old Pinus halepensis and its hybrids. We observed that storage of cuttings before rooting at 4°C for 4 weeks and prolong immersion of cuttings in a solution containing 400 mg/l of indole-3-butyric acid, 5 mg/l of the auxin conjugate 2-(2,4-dichlorophenoxy)propanoic acid-glycine methyl ester, and 0.01% of Amistar fungicide significantly improved rooting of mature cuttings. The active ingredient in Amistar is azoxystrobin, an uncoupler of respiration, which seems to directly promote rooting. Rooted cuttings of selected clones demonstrated unique and uniform growth performance, most likely delivering the intrinsic growth parameters of the mother trees. It was also observed that trees growing under drought stress possess improved rooting ability. By using rooted cuttings, it will be possible to study the relationship between growth rate and adaptation to semi-arid climate conditions. The ability to clonal propagate mature and old P. halepensis trees not only enables vegetative propagation of elite trees for improvement programs, but also provides an opportunity to preserve unique naturally occurring old P. halepensis genotypes.

In: Israel Journal of Plant Sciences