Genetic structure, differentiation, and slight evidence for no selective neutrality of some SSR markers in populations of Medicago ciliaris (L.) Krock and Medicago intertexta (L.) Mill species

Authors : Fella ABDOUS, Fatima Zohra FYAD-LAMECHE

Pages : 99-110

View : 12 | Download : 3

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Medicago ciliaris insert ignore into journalissuearticles values(L.); Krock and Medicago intertexta insert ignore into journalissuearticles values(L.); Mill are most often found in saline regions and are considered as potential resources for genes related to salinity resistance. To explore the genetic diversity of these two species by mean of nrSSR insert ignore into journalissuearticles values(simple-sequence repeats); markers, 11 accessions originated from different regions in north of Africa and Middle East were chosen. Ten among 14 markers turned out to be polymorphic and gave 72 alleles. Eight markers were very informative with PIC values > 0.5, and three of them were found to be nonneutral. Allelic richness was limited with an average number of alleles per locus of 2.7. All populations have a significant heterozygous deficit evidenced by both observed heterozygosity rates insert ignore into journalissuearticles values(null for most populations); and multilocus fixation index estimates. A strong differentiation between populations was highlighted by F-ST insert ignore into journalissuearticles values(0.805); and Ginsert ignore into journalissuearticles values(ST); insert ignore into journalissuearticles values(0.919); values. Low values of gene flow insert ignore into journalissuearticles values(0.01-0.38); revealed a very weak gene exchange between populations regardless of the proximity of their sites of origin. The total variability breakdown by analysis of molecular variance insert ignore into journalissuearticles values(AMOVA test); showed a preponderance of interpopulation component insert ignore into journalissuearticles values(73%-72%); with respect to intrapopulation one insert ignore into journalissuearticles values(18%);, mainly due to the mating system. Relationship analysis performed by NJ tree representation trends to place M. ciliaris as an ancestor and M. intertexta as a derivative. The two populations from the Sebkha site, characterized by the highest variability and more private alleles, constitute an ideal reservoir of genes for tolerance to salinity. Significant genetic diversity in the two aforementioned species is encouraging for their conservation.
Keywords : Genetic diversity, genetic structure, M ciliaris, M intertexta, salinity tolerance, simple sequence repeats