Enhancement of growth and salt tolerance of rice seedlings (Oryza sativa L.) by regulating ethylene production with a novel halotolerant PGPR strain Glutamicibacter sp. YD01 containing ACC deaminase activity

Abstract

Plant growth-promoting rhizobacteria can stimulate not only plant growth and development, but also alleviate the negative effects on plants caused by abiotic stresses. In this study, a novel halotolerant strain was isolated and identified as Glutamicibacter sp. (YD01) using 16S rDNA analysis. This strain tolerated up to 10% NaCl and showed two growth-promoting traits such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme activity and IAA production. Glutamicibacter sp. YD01 inoculation could enhance tolerance of rice (Oryza sativa L.) plants to salt stress by regulation of plant ethylene production, ACC content, ACC oxidase activity and improving K+ acquisition. Moreover, strain YD01-inoculated rice exhibited lower levels of Na+ accumulation and electrolyte leakage under salt treatment compared to non-inoculated ones. Inoculated rice also showed higher transcript levels of genes encoding antioxidants and genes involved in salt tolerance than the plants with no inoculation. In summary, this study showed the important role of Glutamicibacter sp. YD01 in the alleviation of the adverse effects of salt stress on growth and development of rice plants through mediation of phytohormone (ethylene) and ROS accumulation, maintaining ion homeostasis, improving photosynthetic capacity and enhancing stress-responsive genes expression. This work provides an economic approach of promoting growth and development of plants under salt stress treatment.