Molecular characterization ofAspergillus nigerisolates inciting black mould rot of onion through RAPD

Abstract

Genetic diversity in black mould rot pathogen (Aspergillus niger Van Tieghem) was analyzed using ten isolates collected from different regions of India. The genomic DNA extracted from each isolates ofAspergillus niger was subjected to polymerase chain reaction using 40 random decamer primers from OPA and OPC series. Only six primers showed amplifications and selected for the analysis. Out of these, all six primers showed 100 per cent polymorphism. The total number of amplified fragments was 159, with a range of 10 to 3 8 fragments per primer. Dendrogram generated by pooled molecular data of six RAPD primers formed two clusters namely ‘A ’and ‘B ’. The cluster ‘A ’was divided into AN-1 and AN-4 isolates, Cluster B was divided into two sub-clusters B1 and B2. Sub-cluster B1 included B11 and B12 cluster. Cluster Bn included isolates viz., AN-02, AN-03, AN-05 and AN-06. Cluster B12included isolate AN-09. Sub-cluster B2 included B21 and B22 cluster. B21 cluster included isolate AN-07 and B22 cluster included isolates AN-08 and AN-10. The similarity coefficient ranged from 0.037 to 0.56 with all the six primers. Highest similarity (0.56) was observed between AN-5 and AN-6 isolates, while lowest similarity (0.037) was observed between AN-1 and AN-2 isolates. Thus, the molecular characterization often isolates of A. niger by RAPD revealed existence of variations.