Xanthine Dehydrogenase Involves in the Response of Photosystem and Reactive Oxygen Metabolism to Drought Stress in Rice

Abstract

Xanthine dehydrogenase (XDH) is a crucial enzyme involved in purine metabolism. Although the essential role of XDH is well studied in leguminous plants and Arabidopsis, the importance of this enzyme remains uncertain in rice. To evaluate how biochemistry indicators respond to XDH down-regulation and up-regulation in rice seedings during drought stress, RNA interference (RNAi) and CDS over-expression were used to generate transgenic lines of Nipponbare (Oryza sativa L.) in which OsXDH, the gene for XDH were silenced and over-expression. When the XDH-suppressed line was subjected to drought stress, the chlorophyll content and chlorophyll fluorescence parameters were markedly reduced in conjunction with significantly O₂⁻ enhanced production rate and MDA accumulation. This drought-hypersensitive biochemistry indicators was reversed in XDH-intensified line. Meanwhile, the XDH activity and its downstream metabolites were induced by drought stress. These observations support the notion that xanthine dehydrogenase was involved in regulating photosystem and reactive oxygen metabolism in drought stress in rice seedling.