Overexpression of URO gene enhances drought resistance in Arabidopsis

Arabidopsis uro mutant has higher IAA content than wild-type plants because of URO (Upright Rosette) gene overexpression. In this study, the results showed that uro mutant displayed improved drought tolerance compared to wild type. However, no evidence showed uro mutant had any drought tolerance related phenotypes such as root length, number of trichomes and the speed of cellular dehydration of leaf explants. In addition, uro mutant exhibited decreased sensitivity to exogenous abscisic acid (ABA). At the same time, the enhanced expression of ABA-responsive genes in uro mutant was delayed obviously relative to wild type after ABA treatment. On the other hand, uro mutant has prolonged vegetable growth and delayed senescence. Especially after osmotic stress treatment, there was much less malondialdehyde (MDA) in uro mutant than in wild type. These results indicate that overexpression of URO gene enhances drought tolerance of uro mutant through an ABA-independent pathway, and the delayed senescence of uro mutant may relate to its high drought tolerance.