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Abstract. Inayati A, Sulistyowati L, Aini LQ, Yusnawan E. 2020. Trichoderma virens-Tv4 enhances growth promoter and plant defense-related enzymes of mungbean (Vigna radiata) against soil-borne pathogen Rhizoctonia solani. Biodiversitas 21: 2410-2419. Trichoderma virens has been studied for its ability to control various soil-borne pathogens as well as to induce plant resistance. The ability of T. virens control R. solani and its capability to induce resistance was evaluated in two different genotypes of mungbean (Vigna radiata (L.) R. Wilczek). Plant growth-promoting capability and production of plant defense-related enzymes during plant-pathogen-Trichoderma interaction were investigated. Pathogen infection caused the morphological and biochemical changes as well as increased plant defense enzymes activity such as peroxidase, polyphenol oxidase, PAL, phenolics, and flavonoid compared to control uninoculated plants. T. virens improved mungbean seedling growth in terms of increased total biomass, root weight, and root length as well as improved chlorophyll content and IAA-synthase from leaves and roots. T. virens treatment alone or in the presence of pathogen-induced mungbean defense-related enzymes indicated by the increasing of PO and PPO activity, and higher accumulation of total phenolic and flavonoid content. Although most of plant induced resistance parameters showed low and non-significant in direct single-factor comparison, Pearson’s correlation showed there was a positive correlation between plant growth promoter compounds (IAA and chlorophyll) with plant defense-related enzymes (total phenol, and flavonoid content). T. virens treatment can induce systemic defense response of mungbean seedling directly by increasing the activity of some defense-related enzymes, and indirectly by improving plant health, and promoting plant growth. In conclusion, T. virens-Tv4 has potential to be developed as bio-control agents to control R. solani as well as to induce mungbean resistance.

Rhizoctonia solani is one of the harmful pathogens on mungbean, which is very challenging to be controlled. T. virens has been studied intensively and has great potency to control R. solani through mycoparasitism. Seven strains of T. virens isolated from various rhizospheres were tested for their mycoparasitic potential by observing their hyperparasitism and the production of hydrolytic enzymes. All strains showed the ability to suppress the growth of R. solani on dual culture assay as well as on culture filtrate test with the inhibition ability from 43.8 to 68.6% on the dual culture assay and from 22.2 to 71.1% on the culture filtrate assay. Inter-fungal interaction, which was observed by an electron microscope, showed hyperparasitic action of T. virens against R. solani involved the formation of the knob-like structure followed by the growth of Trichoderma hyphae inside host mycelia, coiling, lysed cell wall, and swollen of mycelial tips. Mycoparasitism of T. virens also correlated with the synthesis of hydrolytic enzymes, such as cellulase and chitinase, which influenced the overall hyperparasitic ability of T. virens against the pathogen. Based on in vitro assay, the Tv3 strain proposed as a promising strain to control R. solani due to its high growth inhibition and relatively high cellulase and chitinase productionse.