Species diversity of Ganoderma causing foot rot of arecanut in southern dry tracts of Karnataka

Abstract

Aim: The present study was undertaken to study the morphological and molecular diversity of Ganoderma spp. causing foot rot of arecanut in dry tracts of Southern Karnataka. Methodology: A total of 20 samples isolated from diseased areca palms in three districts of Karnataka were identified based on morphological and molecular characteristics. Qualitative data of cultural characteristics were transformed into code and a binary matrix was generated. Total genomic DNA was isolated and ITS region was amplified using universal primers ITS1 and ITS4. PCR amplicon was directly sequenced and phylogenetic analysis was carried out. Results: The dendrogram generated from the cultural morphological characteristics showed clear variations among Ganoderma isolates causing foot rot. DNA amplification of Ganoderma isolates with fungal universal primers (ITS1 and ITS4) was observed at 650 bp in all isolates tested. Taxonomic correlation of isolates upon NCBI web proved that the isolates were genetically related to Ganoderma spp. with 89-99.49 per cent identity and confirmed the taxonomic identity of isolates used in this study. Interpretation: Phylogenetic analysis of arecanut isolates of southern Karnataka are distinct as evidenced by forming separate cluster. Based on gene homology, G. ryvardenni and G. casuarinicola are new species reported as causal agent of foot rot in arecanut from Karnataka. The ITS gene sequences of four isolates viz., AG3 (MN 784436), AG4 (MN 784437), AG11 (MN 784438), and AG20 (MN 78449) were deposited in NCBI gene bank. Key words: Arecanut, Foot rot, Ganoderma, Phylogeny, Species diversity