Plasma membrane intrinsic protein SlPIP1;7 promotes root growth and enhances drought stress tolerance in transgenic tomato (Solanum lycopersicum) plants

Abstract Plasma membrane intrinsic proteins (PIPs) play important roles in mediating water transport and regulating plant growth and development. In this study, the function of SlPIP1;7 in drought stress tolerance was characterized. Overexpression of SlPIP1;7 in tomato increased the primary root length and promoted the lateral root growth, whereas the shoot and root growth of SlPIP1;7 ‐silenced seedlings were severely retarded. Moreover, SlPIP1;7 ‐overexpressing plants exhibited obviously increased drought stress tolerance because they showed slight withering symptom, whereas the SlPIP1;7 ‐silenced plants were more sensitive to drought stress. Furthermore, the SlPIP1;7 ‐overexpressing plants showed higher root hydraulic conductivity (Lpr) and less cell membrane damage and produced less reactive oxygen species (ROS) accumulation under drought stress compared with wild‐type, whereas these indicators were opposite in SlPIP1;7 ‐silenced plants. These results suggested that overexpression of SlPIP1;7 gene promoted the root growth and the water absorption, maintained the water balance and increased the antioxidant defence ability of plants under drought stress, thereby imparting the drought stress tolerance. SlPIP1;7 is thus a valuable genetic resource to enhance stress tolerance in tomato plants.