To study the Genetic diversity of Colletotrichum isolates, the pathogen of Anthracnose in legumes using ITS markers”.

Abstract

Molecular markers are useful tools for evaluating genetic diversity and determining cultivar identity. The purpose of this study was to evaluate the genetic diversity within a diverse collection of nineteen genotypes Colletotrichum isolates accessions and to determine differencesin the patterns of diversity among Colletotrichum using six twelve ITS markers. The average number of polymorphic bands was 8.6 per primer. ITS analysis generated a total of fifty two bands from twelve primers, of which 100% were polymorphic. The approximate size of the largest DNA fragment produced was 638-550 bp for CaInt2 & CgInt primer pair while T1 & Bt2b primer pair registered the smallest amplitude of amplified fragments size is 300 bp.PIC values ranged from 0.05 to 1.89, with an average of 0.725, which revealed that much variation waspreent among the studied isolates . The highest number of polymorphic markers was seventeen produced from T1 & Bt2b primers (100%). The resolving power (RP) varies between 0.1 for GDF1 & GDR1 to 0.95 for ITS5 & ITS6 with an average value of 0.56. GDF1 & GDR1showed the lowest resolving power, while ITS5 & ITS6 showed maximum resolving power. Out of six marker pairs three showed higher resolving power than average resolving power were ITS5 & ITS6, ITS1 & ITS4 and CaInt2 & CgInt. The degree of genetic relatedness among isolates of Colletotrichum spp. varied considerably from GS value ranging from 0.50 to 0.9167, due to diversification in terms of morphology, maturity groups, parentages and geographical distribution. The isolates BH-4 and UH-3 have same origin and are nearest close to the UH-5, UH- 9 and UH-13 whereas, The isolates UH-14 and BH-2 have same origin and are nearest close to the UH-6, UH-9, BH-6 and UH-13. The genetic diversity analysis done by NTSYS-pc software. The analysis of representative Colletotrichum spp. isolates associated with legume crops using molecular markers supported the categorization of the isolates into different clusters. These were closely related as indicated by their nearly genetic relationship, overlapping morphological and cultural characters and similar habit.