Genetic variability and relationships among seventeen Trichoderma isolates to control dry root rot disease using RAPD markers.

Trichoderma spp. has been identified as potential antagonist of Fusarium solani, which is causing dry root rot of Citrus. A random amplified polymorphic DNA (RAPD) marker was used to estimate the genetic variation among 17 isolates of Trichoderma. These isolates were characterized using 20 random primers of the OPM series, out of which 16 primers gave a total of 145 DNA fragments, showing 91.8% polymorphism. The genetic distance between each isolate was calculated, and cluster analysis was used to generate a dendrogram showing the relationship among them. The isolates grouped into two major clusters, the first major cluster consisted of TCT14, TCT17, TCT13, TCT12 and TCT16. The remaining isolates in the second major cluster separated in two sub-clusters; the first cluster consisted of TCT4, TCT10, TCT2, TCT3, TCT8, TCT6, TCT9, and the second sub-cluster consisted of TCT1 TCT15 TCT5, TCT11, and TCT7. The similarity matrix indicated that TCT6 and TCT13 were genetically distinct as they showed only 22.6% similarity followed by TCT5 and TCT16; TCT6 and TCT16 (25%), while the isolates TCT4 and TCT10 were found to be genetically similar, as 66.7% similarity was observed between the isolates followed by 61.3% similarity between the TCT2 and TCT4 isolates.