Diversity assessment of the Lebanese germplasm of pomegranate (Punica granatum L.) by morphological and chemical traits

Pomegranate (Punica granatum L.) is one of the oldest edible fruits cultivated in Lebanon but the diversity of its germplasm has not been addressed yet. The present study presents the first assessment of local pomegranates growing in the country. A set of 78 pomegranate local accessions sampled from the main production areas across the country were evaluated by using twenty-eight quantitative and ten qualitative descriptors. A large variability was revealed among accessions based on the traits studied. Principal component analysis showed that male and hermaphrodite flowers, petal width as well as fruit weight, diameter and length, in addition to juice pH and sugar/acid ratio, were the most discriminating traits. Big sized fruits up to 358.6 g were found for Lefani SL67, Lefani ML25 and Mokh El Baghl SL59 accessions while the juiciest fruits were recorded for Mokh El Baghl SL65, Hamod BH41 and Hamod B54 accessions with 75–78%. The PCA bi-plot allowed to differentiate the studied accessions in three main groups based mainly on the juice pH and sugar/acid ratio: the sweet accessions called Helou, the intermediate taste accessions named Lefani and the sour accessions generally designated as Hamod. Although preliminary, the results of this study indicate a significant diversity within the Lebanese pomegranate germplasm that should be further completed by a DNA analysis to understand the genetic structure of this germplasm with respect to conservation and breeding strategies

Evolution of almond genetic diversity and farmer practices in Lebanon: impacts of the diffusion of a graft-propagated cultivar in a traditional system based on seed-propagation

Abstract Background Under cultivation, many outcrossing fruit tree species have switched from sexual reproduction to vegetative propagation. Traditional production systems have persisted, where cultivar propagation is based on a mixed reproductive system. For millenia, almond, Prunus dulcis, has been propagated by seeds. Almond grafting remained of little importance until recently. In Lebanon, both sexual and clonal reproductions are used for almond propagation. We used 15 microsatellite markers to investigate the effect of introducing graft-propagated cultivars and associated practices, on the structure of the genetic diversity among and within the two main Lebanese cultivars. Results As expected, the sexually propagated cultivar Khachabi exhibited more genotypic and genetic diversity than the vegetatively propagated cultivar Halwani. It also exhibited lower differentiation among populations. The distribution of clones showed that propagation modes were not exclusive: farmers have introduced clonal propagation in the seed-propagated cultivar while they have maintained a diversity of genotypes within populations that were mostly graft-propagated. These practices are also important to avoid mate limitations that hamper fruit production in a self-incompatible species. ‘Khachabi’ is structured into two gene pools separated by the Lebanese mountains. As to ‘Halwani’, two different gene pools were introduced. The most ancient one shares the same geographic range as ‘Khachabi’; longtime coexistence and sexual reproduction have resulted in admixture with ‘Khachabi’. In contrast, the more recent introduction of the second gene pool in the Bekaa region followed an evolution towards more extensive clonal propagation of ‘Halwani’ limiting hybridizations. Furthermore, some pairs of geographically distant ‘Halwani’ orchards, exhibited low genetic distances, suggesting that a network of exchanges between farmers was effective on a large scale and/or that farmers brought clonal plant material from a common source. Conclusions Almond diversification in Lebanon is clearly related to the evolution of propagation practices adapted to self-incompatible cultivars. The comparison between both cultivars demonstrated the genetic effects of the introduction of a new cultivar and the associated grafting propagation practices. Our study provided information to develop a strategy for in situ conservation of cultivars and to limit gene flow from introduced material to ancient orchards

Additional file 6: of Evolution of almond genetic diversity and farmer practices in Lebanon: impacts of the diffusion of a graft-propagated cultivar in a traditional system based on seed-propagation

Figure S3. Plot of genetic distance (Dc) and geographic distance for A) 14 ‘Khachabi’ populations; B) 11 ‘Halwani’ populations. Significance at α = 0.05. (TIF 23 kb

Data from: Evolution of almond genetic diversity and farmer practices in Lebanon: Impacts of the diffusion of a graft-propagated cultivar in a traditional system based on seed-propagation

We sampled a large range of cultivated individuals from different agro-climatic areas in Lebanon, and analyzed them with a set of 15 SSRs markers selected for their producibility and polymorphism in almond and other Prunus species.The most common and oldest cultivar is known as 'Khachabi', it has been cultivated by seeds. The other cultivar called 'Halwani', probably introduced last century, it has been widely propagated by grafts. <br

Additional file 3: of Evolution of almond genetic diversity and farmer practices in Lebanon: impacts of the diffusion of a graft-propagated cultivar in a traditional system based on seed-propagation

Table S2. Genotypic linkage disequilibrium for pairwise comparisons between loci conducted over different data sets without redundant MLGs. – data not available; The coefficient of correlation is indicated for P > 0.05. (XLS 45 kb

Additional file 2: of Evolution of almond genetic diversity and farmer practices in Lebanon: impacts of the diffusion of a graft-propagated cultivar in a traditional system based on seed-propagation

Table S1. Statistics associated with microsatellite loci. Na, total number of alleles; PIC, polymorphic information content; Ho, observed heterozygosity; He, unbiased expected heterozygosity; Fis, inbreeding index calculated based on a matrix of N individuals or G genotypes; f (Null), estimation of significant frequency of null alleles. (a) Cipriani et al. 1999; (b) Testolin et al. 2000; (c) Sosinski et al. 2000; (d) Dirlewanger et al. 2002; (f) Aranzana et al. 2002. * HW significance with Bonferroni correction (P < 0.01). Fis (N) values were calculated with all trees found including repeated clone genotype. Fis (G) values were calculated with only one individual per multi locus genotype (MLG). (XLS 28 kb