Genetic diversity and population structure of Vigna exilis and Vigna grandiflora (Phaseoleae, Fabaceae) from Thailand based on microsatellite variation

The objective of this research was to determine the genetic diversity and population structure of natural populations of two rare wild species of Asian Vigna (Phaseoleae, Fabaceae), Vigna exilis Tateishi & Maxted and Vigna grandiflora (Prain) Tateishi & Maxted, from Thailand. Employing 21 simple sequence repeat markers, 107 and 85 individuals from seven and five natural populations of V. exilis and V. grandiflora, respectively, were analyzed. In total, the markers detected 196 alleles for V. exilis and 219 alleles for V. grandiflora. Vigna exilis populations showed lower average values in number of alleles, allelic richness, observed heterozygosity, gene diversity, and outcrossing rate than V. grandiflora populations, namely 58.00% versus 114.60%, 51.96% versus 74.80%, 0.02% versus 0.18%, 0.40% versus 0.66%, and 3.24% versus 17.41%, respectively. Pairwise FST among populations demonstrated that V. exilis was much more differentiated than V. grandiflora. Analysis of molecular variance revealed that 41.83% and 15.06% of total variation resided among the populations of V. exilis and V. grandiflora, respectively. Seven and two genetic clusters were detected for V. grandiflora and V. exilis by STRUCTURE analysis. Our findings suggest that different strategies are required for in situ conservation of the two species. All V. exilis populations, or as many as possible, should be conserved to protect genetic resources of this species, while a few V. grandiflora populations can capture the majority of its genetic variation. Key words: Vigna, microsatellite marker, mung bean, population genetics, simple sequence repeat. Resume : L'auteur a cherche a determiner la diversite genetique et la structure des populations naturelles de deux especes indigenes rares de Vigna (Phaseoleae, Fabaceae), Vigna exilis Tateishi & Maxted, et Vigna grandiflora (Prain) Tateishi & Maxted, de Thailande. En utilisant des marqueurs de 21 sequences repetitives simples, il a analyse 107 et 85 individus provenant de sept et cinq populations naturelles du V. exilis et du V. grandiflora, respectivement. Les marqueurs ont detectes 196 alleles pour V. exilis et 219 alleles pour V. grandiflora. Les populations du V. exilis montrent des valeurs moyennes plus faibles pour le nombre d'alleles, la richesse allelique, l'heterozygocite observee, la diversite des genes et le taux d'heterocroisements, que chez les populations du V. grandiflora, etant de 58,00% vs 114,60%, 51,96% vs 74,80%, 0,02% vs 0,18%, 0,40% vs 0,66%, et 3,24% vs 17,41%, respectivement. La FSTpairee entre populations demontre que le V. exilis estbeaucoup plus differencie que le V. grandiflora. L'analyse de la variance moleculaire revele que 41,83% et 15,06% de la variation totale se retrouve dans les populations du V. exilis et du V. grandiflora, respectivement. En utilisant l'analyse STRUCTURE, l'auteur a detecte sept et deux clusters genetiques chez les V. grandiflora et le V. exilis. Ces constatations suggerent que differentes strategies sont necessaires pour la conservation in situ des deux especes. On devrait conserver toutes ou autant de populations que possible du V. exilis pour proteger la ressource genetique de cette espece, alors que quelques populations du V. grandiflora peuvent retenir la majorite de sa variation genetique. [Traduit par la Redaction] Mots-cles: Vigna, marqueur microsatellite, haricot mungo, genetique des populations, sequences repetitives simples.
Introduction Vigna subgenus Ceratotropis (Phaseoleae, Fabaceae), commonly known as Asian Vigna, is composed of about 23 species, with Asia as their center of diversification. Species in this subgenus are classified [...]