A rice XANTHINE DEHYDROGENASE gene regulates leaf senescence and response to abiotic stresses

Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine dehydrogenase affects rice growth and development are poorly understood. In the present study, we identified a mutant with early leaf senescence and reduced tillering that we named early senescence and less-tillering 1 (esl1). Map-based cloning revealed that ESL1 encodes a xanthine dehydrogenase, and it was expressed in all tissues. Chlorophyll content was reduced and chloroplast maldevelopment was severe in the es11 mutant. Mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents. Further analysis revealed that the accumulation of reactive oxygen species in esl1 resulted in decreased photosynthesis and impaired chloroplast development, along with increased sensitivity to abscisic acid and abiotic stresses. Ttranscriptome analysis showed that the ESL1 mutation altered the expression of genes involved in the photosynthesis process and reactive oxygen species metabolism. Our results suggest that ESL1 is involved in purine metabolism and the induction of leaf senescence. These findings reveal novel molecular mechanisms of ESL1 gene-mediated plant growth and leaf senescence. (C) 2021 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

Automated summary

Xanthine dehydrogenase, encoded by the ESL1 gene, plays a crucial role in purine metabolism and leaf senescence in rice. Mutation of ESL1 results in decreased chlorophyll content, impaired chloroplast development, and altered levels of allantoin, allantoate, and ABA. Additionally, ESL1 mutation leads to increased sensitivity to abscisic acid and abiotic stresses, along with changes in gene expression related to photosynthesis and reactive oxygen species metabolism.