Plant Growth-promoting Activities of Penicillium sp. NAUSF2 Ameliorate Vigna radiata Salinity Stress in Phosphate-deficient Saline Soil

The halotolerant phosphate-solubilizing fungus Penicillium sp. NAUSF2 was isolated from rhizospheric soil in coastal regions of South Gujarat, India, and identified on the basis of morphological characteristics and internal transcribed spacer gene sequence (ITS1 and ITS4). The isolate solubilized rock phosphate up to 843 mu M. There was drop in pH with the secretion of gluconate (31.7 mM) and oxalate (3.2 mM) mediated by the high glucose oxidase and oxaloacetate acetylhydrolase activities, respectively. This fungus also demonstrated plant growth-promoting activities such as indole-3-acetic acid (127.82 g/L) and siderophore production. Inoculation of Penicillium sp. NAUSF2 to Vigna radiata (mung bean) significantly increased plant P uptake and growth parameters. It showed reduced disease severity index due to increased levels of antioxidative enzymes and jasmonic acid when treated with the leaf spot pathogen Xanthomonas axonopodis pv. V. radiata. These results suggest the potential of Penicillium sp. NAUSF2 as a biotechnological tool to help plants to cope up with stress in saline soils and broaden the spectrum of phosphate solubilizers available for field application.