Pathogenicity and rDNA-ITS sequence analysis of the Corynespora cassiicola isolates from rubber plantations in Indonesia

Corynespora cassiicola is an important pathogen causing Corynespora leaf fall disease on the rubber tree. Analysis of virulence and rDNA-ITS sequence were undertaken to investigate the effect of agro-climatic conditions and host rubber clones to virulence of 23 C. cassiicola isolates on six clones (RRIC 100, BPM 24, BPM 1, PB 260, GT 1 and RRIM 600) and to observed the evolution pattern of C. cassiicola isolates. Virulence analysis showed that there is an interaction between isolates and clones, indicating the differences of each isolates virulence to six clones. Agro-climatic conditions and host clones influenced the virulence of isolates and rDNA-ITS sequence variation. Analysis of rDNA-ITS showed that there were three of Single Nucleotide Polymorphism (SNP) that separated of isolates into 5 haplotypes. Most of the isolates belonging to the haplotype 1. Phylogenetic analysis indicated that C. cassiicola have a high diversity, however the clustering did not indicate country and host species of isolates. This information will be very useful on developing strategies of disease management and rubber plant breeding towards resistance to CLF disease.