Endocellulase SlGH9-21 significantly improves drought resistance and storage capacity of tomato

•The silencing of the SlGH9-21 gene increased the drought resistance of tomato.•The silencing of SlGH9-21 gene delayed fruit ripening by about 10 days and significantly enhanced the mechanical hardness of tomato fruits during and after ripening.•The silencing of SlGH9-21 gene may significantly prolong the postharvest storage time of tomato fruits by affecting the mechanical hardness and degradation of cellulose, which is the main component of fruit cell wall.