Ribosomal DNA Sequence Based Characterization of Trichoderma Isolates Antagonistic to Colletotrichum falcatum Causing Red Rot Disease of Sugarcane

Trichoderma bioagent isolates cultured from the sugarcane rhizosphere of subtropical India, and established efficient against Colletotrichum falcatum Went (red rot pathogen) in sugarcane are described based on phylogenetic analysis of nucleotide sequences. DNA sequences of the isolates included the internal transcribed spacer (ITS) regions of the rDNA cluster (ITS1-5.8S- ITS2). The 5.8S region was found conserved and much of the sequence variability was due to indels or transition/transversion mutations in the ITS1 and 2 regions. Both the isolates belonged to the T. harzianum clade. These isolates are distinct yet have close genetic similarity with several established strains/isolates of T. harzianum reported worldwide. Correct identification of these bioagents would augment the effective utilization of these fungi of immense agricultural importance in managing the red rot disease of sugarcane.