Actinomycetes and their secondary metabolites to control multiple pathogens of Actinomycetes and their secondary metabolites to control multiple pathogens of chickpea and sorghum chickpea and sorghum S. Gopalakrishnan* and GV Ranga Rao S. Gopalakrishnan* and GV Ranga Rao ICRISAT, Patancheru, Hyderabad, Andhra Pradesh, India ICRISAT, Patancheru, Hyderabad, Andhra Pradesh, India *Corresponding author: [email protected] SRI CONT INTRODUCTION INTRODUCTION In the present study, 25 different herbal In the present study, 25 different herbal vermicomposts were screened for actinomycetes that contain vermicomposts were screened for actinomycetes that contain antifungal potential against antifungal potential against Fusarium Fusarium wilt and collar rot of wilt and collar rot of chickpea (caused by chickpea (caused by Fusarium oxysporum Fusarium oxysporum f. sp. f. sp. ciceri ciceri and and Sclerotium Sclerotium rolfsii rolfsii , respectively) and charcoal rot of sorghum (caused by , respectively) and charcoal rot of sorghum (caused by Macrophomina phaseolina Macrophomina phaseolina ) and anti-insect potential against ) and anti-insect potential against Helicoverpa armigera Helicoverpa armigera , the polyphagous pest of many crops. The , the polyphagous pest of many crops. The promising ones were selected further for metabolite promising ones were selected further for metabolite purification studies. purification studies. MATERIALS AND METHODS MATERIALS AND METHODS Prominent actinomycetes isolated with SCA by spread plate methods. In-vitro antifungal activity by dual-culture assay. In-vivo anti-insect activity by bioassay (on 3 rd instar Helicoverpa larvae) Evaluated for PGP traits on respective selective media. Actinomycetes identified by 16S rDNA analysis. Metabolite production capability by solvent partitioning and bioassay. Partial purification done by SPE and open column chromatography. RESULTS RESULTS Three most promising actinomycetes (CAI-21, CAI-26 and MMA- 32) based on biocontrol and PGP traits were further studied CAI-21 was identified as Streptomyces albus, while CAI-26 and MMA-32 were identified as S. champavatii and S. roseoviolaeus, respectively. Culture filtrates of all the three actinomycetes completely inhibited FOC but not M. phaseolina completely. However, all the culture filtrates inhibited another pathogen of chickpea, Sclerotium rolfsii which causes collar rot. Culture filtrates of all the actinomycetes showed 58-78% mortality over control. Upon further fractionation of the culture filtrates of one of the actinomycetes (CAI-21) by open column chromatography, only 80% MeOH fraction showed inhibition of FOC. Molecular identification of the potential actinomycetes The list of herbal vermicomposts used in this study Jatropha curcas, Annona squamosa, Parthenium hysterophorus, Oryza sativa, Gliricidia sepium, Adhatoda vasica, Azadirachta indica, Capsicum annuum, Calotropis gigantea, Calotropis procera, Datura metal , Allium sativum, Zingiber officinale, Ipomoea batatas, Momordica charantia, Moringa oleifera, Argyranthemum frutescens , Nerium indicum, Allium cepa, Curcuma aromatica, Pongamia pinnata, Abacopteris multilineata , Nicotiana tabacum, Tridax procumbens and Vitex negundo The effect of culture filtrates of actinomycetes on F The effect of culture filtrates of actinomycetes on S. 0 20 40 60 80 100 CA I-21 CA I-26 M M A-32 C ontrol A ctinom ycetes % M ortality The effect of culture filtrates of actinomycetes on H. a 0 0.01 0.02 0.03 0.04 0.05 0.06 CA I-21 CA I-26 M M A-32 C ontrol A ctinom ycetes D ry w t(g) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 CA I-21 CA I-26 M M A-32 C ontrol A ctinom ycetes D ry w t(g) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 Con Crude C rude 4T NAF 10% 20% 40% 60% 80% 80% 4T 100% O pen colum n fractions in M eO H (adsorbed) D ry w eight(gm Fractionation of culture filtrates of CAI-21 on an open column chromatography: on FOC Strains Matched with NBAIM ACC No CAI-21 Streptomyces albus NAIMCC-B-01089 CAI-26 Streptomyces champavatii NAIMCC-B-01090 MMA-32 Streptomyces roseoviolaeus NAIMCC-B-01091 control and PGP traits of the actinomycetes On FOC On M. phaseolina On S. rolfsii The effect of culture filtrate of CAI-21 on various pathogens