Analysis of Genetic Diversity and Population Structure in Horsegram (Macrotyloma uniflorum) Using RAPD and ISSR Markers

Abstract

Macrotyloma uniflorum (horsegram) is an underutilized warm season pulse crop used as food and fodder in many semi arid regions of the world. In the present study, genetic structure and diversity of M. uniflorum was analysed using RAPD and ISSR markers. Two other species of the genus Macrotyloma namely M. axillare and M. sar-gharwalensis were also included to assess genetic inter-relationships. In total, 25 polymorphic primers amplified 156 fragments ranging in size from 300 to 3000 bp. Primer wise fragments ranged from 2 (OPR-20) to 13 (OPB-5, OPB-12 and OPS-14) with an average of 6.24 fragments per primer. Highest PIC value of 0.499 was recorded for primer OPR-20 and lowest (0.013) for primer OPR-2 with an average of 0.344. STRUCTURE analysis clustered accessions on the basis of their geographic origin and showed the presence of two distinct gene pools. Dendrogram based on Jaccards similarity coefficient also grouped the accessions into two groups and revealed that M. sar-gharwalensis is more distantly related to the cultivated than M. axillare. PCA analysis also confirmed clustering results shown by STRUCTURE. Partitioning of genetic variation using AMOVA revealed 63 % within population variation with only 37 % genetic variation among populations. Few horsegram accessions showed high levels of genetic diversity which can be exploited in crop breeding programmes for its genetic improvement.