PIIN_05330 transgenic Arabidopsis plants enhanced drought-stress tolerance

Serendipita indica is a root endophytic fungus and can symbiose with many plant species. Effector proteins secreted by fungi show many functions during symbiosis or infection. To investigate the role of the protein PIIN 05330 secreted by S. indica, the gene PIIN_05330 was cloned and its transgenic Arabidopsis lines were constructed. The transgenic lines were evaluated for their drought tolerance. The results showed that these transgenic Arabidopsis lines were sensitive to drought stress during the germination stage. Compared with Arabidopsis wild type (WT) and the empty vector (VT) lines seedlings, the transgenic lines had higher total root surface area, root diameters, total root volumes, relative root elongation rates, total root length, and root tip numbers. In addition, the transgenic lines showed higher aboveground biomass and chlorophyll levels. Compared with WT and VT lines, activities of SOD, POD and CAT increased in the transgenic Arabidopsis lines under drought condition, especially their CAT activities. Under drought stress, levels of AsA and GSH in the transgenic lines were higher than those in control WT and VT, and concentrations of H2O2 and MDA were significantly lower than those in control WT and VT. Under drought stress, proline concentrations increased, and total concentrations of soluble sugars and proteins significantly increased in transgenic lines, compared with control WT and VT, indicating that the transgenic lines had a higher ability to reduce plant damage and protect plant cell membrane system. All these results suggest that the effector protein PIIN_05330 improved drought tolerance of the transgenic Arabidopsis lines.