Molecular characterisation of Trichoderma species using SRAP markers

Trichoderma are commonly used as bio control agents in various agro ecosystems. They are known to produce a variety of compounds that induce resistance responses in plants. Among different species of Trichoderma, T. harzianum, T. viride, T. koningii and T. hamatum are commercially used as bio control agents. In the present study, four commercially important species of Trichoderma isolated from coffee ecosystem were screened with sequence related amplified polymorphism (SRAP) markers. Among 48 SRAP primer pairs tested, 29 primers were polymorphic and generated 316 distinct scorable fragments. Out of 347 amplified fragments, 177 fragments were found polymorphic with an average of 6.10 fragments per primer combination. The average polymorphism information content (PIC) and resolving power (Rp) of the 29 polymorphic SRAP primer pair were 0.42 and 14.62, respectively. The UPGMA dendrogram clearly divided Trichoderma species into two broad clusters. The highest homology (83.0%) was observed between T. viride and T. Harzianum and the lowest homology (74.0%) was observed between T. Harzianum and T. konangii. Further, among 29 polymorphic SRAP markers screened, four primer pairs (ME1-EM3, ME1-EM20, ME1-EM22 and ME2-EM4) produced unique fragments specific to each species. These markers can be useful in easy and rapid identification of the species.