Premature leaf senescence affects plant growth and yield in rice. NAD plays critical roles in cellular redox reactions and remains at a sufficient level in the cell to prevent cell death. Although numerous factors affecting leaf senescence have been identified, few involving NAD biosynthetic pathways have been described for plants. Here, we report the cloning and characterization of Leaf Tip Senescence 1 (LTS1) in rice (Oryza sativa), a recessive mutation in the gene encoding O. sativa nicotinate phosphoribosyltransferase (OsNaPRT1) in the NAD salvage pathway. A point mutation in OsNaPRT1 leads to dwarfism and the withered leaf tip phenotype, and the lts1 mutant displays early leaf senescence compared to the wild type. Leaf nicotinate and nicotinamide contents are elevated in lts1, while NAD levels are reduced. Leaf tissue of lts1 exhibited significant DNA fragmentation and H 2 O 2 accumulation, along with up-regulation of genes associated with senescence. The lts1 mutant also showed reduced expression of SIR2-like genes (OsSRT1 and OsSRT2) and increased acetylation of histone H3K9. Downregulation of OsSRTs induced histone H3K9 acetylation of senescence-related genes. These results suggest that deficiency in the NAD salvage pathway can trigger premature leaf senescence due to transcriptional activation of senescence-related genes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.