Evaluation of Broad-Spectrum Streptomyces sp. for Plant Growth Promotion Traits in Chickpea (Cicer arietinum L.)

Abstract

The study evaluated three strains of Streptomyces (CAI-21, CAI-26 and MMA-32) for their plant growth promoting (PGP) traits in chickpea (Cicer arietinum L.) under field conditions in two consecutive post-rainy seasons, 2012–2013 and 2013–2014, to confirm colonizing ability in chickpea and to demonstrate gene expression profiles of indoleacetic acid, siderophore and β- 1,3-glucanase genes. The Streptomyces enhanced nodule number, nodule weight, root weight and shoot weight at 30 d after sowing (DAS) and plant height, pod number, pod weight, leaf area, leaf weight and stem weight at 60 DAS in both seasons over the uninoculated control. At crop maturity, the Streptomyces enhanced stover yield, grain yield and total dry matter in both seasons over the uninoculated control. In the rhizosphere, the biological and mineral nutrient activities, such as microbial biomass carbon, dehydrogenase activity, total nitrogen, available phosphorus and organic carbon were also found higher in plots inoculated with Streptomyces in both seasons over the uninoculated control plots. Scanning electron microscopy analysis revealed that the Streptomyces colonized the roots of chickpea. Quantitative real time PCR analysis on selected PGP genes of Streptomyces revealed up-regulation of β-1,3-glucanase gene in CAI-26, β-1,3-glucanase and siderophore genes (siderophore synthetase) in CAI-21 and β-1,3-glucanase, siderophore (siderophore synthetase) and indole-3-acetic acid (IAAH and IAAM) genes in MMA-32. The three Streptomyces demonstrated broad-spectrum PGP activity.