Molecular and Pathological Characterization of Colletotrichum falcatum InfectingSubtropical Indian Sugarcane

摘要

Red rot, caused by Colletotrichum falcatum, is the mostsignificant problem of sugarcane worldwide. Pathologicalstudies and three different marker systems wereused to characterize 25 C. falcatum isolates collectedfrom 18 subtropical sugarcane cultivars from 15 differentsugarcane-growing regions of three north-easternstates of India to assess pathogen diversity. Of these 25isolates, three were new (RR2A, RR15, RR83) fromcultivars Co 7717, Co J83 and Co S88230, respectively,pathologically characterized on 13 standard differentialhosts. Isolates Cf 01, Cf 08 and RR15 were the most,and Cf-07 the least virulent. Molecular characterizationusing random amplified polymorphic DNA, universalrice primers (URP) and inter simple sequence repeatmarkers amplified a total of 161 alleles of which 159were polymorphic (98.76%). Unweighted paired groupmethod with arithmetic averages analysis of combineddata of all the DNA markers obtained by three markersystems classified 25 isolates into six clusters at 34%genetic similarity with high Mantel matrix correlation(r = 0.83). The principal component analysis (PCA) ofmarker data explained 68% of the variation by firstthree components. Molecular diversity as revealed inthese isolates is very high, but non-structured. IsolateCo Pant 84212 was found to be genetically mostdiverse. We demonstrated for the first time that URPsderived from weed rice could successfully assess geneticdiversity in C. falcatum. Molecular characterization ofthe C. falcatum isolates prevalent in north-easternIndia would enable red rot management strategies,selection for resistance genes and development ofresistant cultivars.