Streptomyces sp. as plant growth-promoters and host-plant resistance inducers against Botrytis cinerea in chickpea

Two hundred and fifty seven actinobacteria, isolated from five different rhizosphere soils of chickpea, were evaluated for their antagonistic potential against Botrytis cinerea, causal agent of Botrytis grey mold (BGM) disease in chickpea, by dual culture assay. Of them, three most promising isolates (ATIRS43, ATIRS65 and ARRS10) with highest inhibitory activity (67-77%) were identified as Streptomyces sp. These selected isolates induced growth of chickpea genotype JG11 as a consortium rather than an individual inoculum. Co-inoculation of the selected Streptomyces sp. with Mesorhizobium ciceri UPM-Ca7(T) enhanced nodulation and nitrogenase activity in five chickpea genotypes (ICCV2, ICCV10, ICC4958, Annigeri and JG11). The selected Streptomyces sp. significantly reduced the disease incidence caused by B.cinerea by 28-47% over the un-inoculated control across the chickpea genotypes ICC4954 (susceptible), ICCV05530 (moderately resistant) and JG11 (unknown resistance). The Streptomyces sp. were also able to induce host-plant resistance, irrespective of the genotype, through the induction of various antioxidant enzymes and phenolics. Phenolic profiling of B.cinerea-affected and Streptomyces treated plants of ICCV05530 further confirmed host-plant resistance traits. This study indicated that the selected Streptomyces sp. have the potential for biological control of BGM disease in chickpea.