Abstract
Although xanthine dehydrogenase (XDH) is known as the rate-limiting enzyme in purine catabolism, the plant physiological role of the function of this enzyme remains still unclear. We previously reported that RNAi-mediated silencing of the two Arabidopsis XDH genes (AtXDH1 and AtXDH2) resulted in xanthine accumulation and pleiotropic phenotypes including growth retardation, impaired fertility and precocious senescence, possibly due to the metabolite deficiency in the catabolic pathway. In this study, we investigated a possible role of XDH in plant acclimatization to drought because the expression of AtXDH1, the major XDH gene in Arabidopsis, is known to be activated by abscisic acid and during the progression of drought stress. Compared with wild-type plants, RNAi plants exhibited significantly more cell death and less chlorophyll contents, and markedly reduced biomass production when subjected to drought stress. These results suggest the functional importance of XDH in the acclimatization to drought.
