Analysis of genetic diversity of Colletotrichum population causing anthracnose in fruit crops using ISSR markers

Abstract

Colletotrichum spp. cause anthracnose disease in several plant species in tropical and temperate regions. In this study, a total of 30 isolates of Colletotrichum spp. were isolated from nine different fruit crops showing anthracnose symptoms. Phylogenetic analysis based on the GAPDH gene divided the population into four primary clades. All C. gloeosporioides species complex grouped together and separated from C. karstii and two different monophyletic lineages i.e. C. brevisporum, C. cliviae. C. gloeosporioides species complex was found dominant within the population containing 7 cryptic species. To study the population diversity of Colletotrichum species, the isolates were grouped into 4 geographical clusters based on their collection site i.e. Delhi, Maharashtra, West Bengal (WB), and North East (NE) states (Assam and Meghalaya). Out of 12 ISSR primers used 11 primers generated scorable polymorphic band of 100-1300 bp having average PIC value of 0.27. The intrapopulation genetic diversity was high in NE population with 78.75% polymorphism. The inter-population genetic distance was high (0.129) between Maharashtra and WB populations. The degree of genetic differentiation was 0.09 and gene flow was estimated at 2.45 within Colletotrichum population. Population stratification using UPGMA dendrogram divided the population into two main groups. Group 1 consisted of isolates from all over the four geographical region and population from NE region formed group 2. The overall result indicates admixture between isolates and homogeneous population structures from different geographical regions.