Premature leaf senescence affects plant growth and yield in rice. Nicotinamide adenine dinucleotide (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 identifiedfor plants.

Recently, scientists from China National Rice Research Institute (CNRRI) of Chinese Academy of Agricultural Sciences (CAAS) have acquired progress on molecular mechanism of leaf senescence in rice. In the study, CNRRI scientists characterized a leaf tip senescence 1 (lts1) mutant and LTS1 encoded an Oryza sativa nicotinate phosphoribosyltransferase 1 (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.