Molecular and pathological characterization of isolates of Colletotrichum falcatum Went. causing red rot in sugarcane

Abstract

Red rot also known as cancer of sugarcane is caused by a pathogen Colletotrichum falcatum (Went.). The disease has a devastating effect as it hinders sugarcane cultivation worldwide. The major way to manage the disease is to develop the disease resistant varieties which require the study of genetic diversity of the pathogen. The present research aim was to study the pathogenic and molecular diversity among the isolates of red rot pathogen collected during surveys of major sugarcane growing areas of Punjab, Haryana and Uttar Pradesh states. Pathogenic assay of isolates on fourteen host differentials grouped them into eight groups on the basis of reaction expressed and virulence frequency. The molecular variation among the isolates using ISSR marker analysis showed high level of polymorphism, which confirmed the variation in virulence pattern of isolates. Polymorphism information content (PIC) and similarity coefficient values varied in the range of 0.227 to 0.321 and 0.29 to 0.93, respectively. The dendrogram grouped isolates in different clusters which reveal considerable level of molecular diversity among the isolates. However, the genetic diversity estimates based on ISSR markers did not show any correspondence with pathogenic variation of the isolates which could be due to same geographical conditions. Nucleotide sequences analysis of the ribosomal DNA (rDNA) genes using universal ITS primers showed the nucleotide variation in the isolates which could be due to base substitution at one to four sites which suggested its role in the origin of virulence and diversity in Colletotrichum falcatum. The presence of ITS variation in the virulent isolates suggested its role in the origin of virulence and diversity in Colletotrichum falcatum. But this needs further verification using proteomic approach for the identification of proteins expressed in relation to pathogenicity.