Down-Regulation of a Nicotinate Phosphoribosyltransferase Gene, OsNaPRT1, Leads to Withered Leaf Tips
Down-Regulation of a Nicotinate Phosphoribosyltransferase Gene, OsNaPRT1, Leads to Withered Leaf Tips
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烟酸磷酸核糖转移酶基因 OsNaPRT1 的下调导致叶尖枯萎
DOI：
10.1104/pp.15.01898
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发表时间：
2016
期刊：
影响因子：
7.4
通讯作者：
Guo Longbiao
中科院分区：
文献类型：
--
作者：
Wu Liwen;Ren Deyong;Hu Shikai;Li Gengmi;Dong Guojun;Jiang Liang;Hu Xingming;Ye Weijun;Cui Yongtao;Zhu Li;Hu Jiang;Zhang Guangheng;Gao Zhenyu;Zeng Dali;Qian Qian;Guo Longbiao
水稻叶片早衰影响植株生长和产量。NAD在细胞氧化还原反应中起关键作用，并在细胞中保持足够的水平以防止细胞死亡。虽然已经确定了许多影响叶片衰老的因素，但很少有涉及植物NAD生物合成途径的描述。本文报道了水稻叶尖衰老基因（Leaf Tip Senescence 1，LTS1）的克隆和特性分析。sativanicotinate phosphoribosyltransferase（OsNaPRT 1）在NAD补救途径中的作用。OsNaPRT1的点突变导致植株矮化和叶尖枯萎表型，与野生型相比，1个突变体表现出叶片衰老早。叶片烟酸和烟酰胺含量升高，而NAD水平降低。1的叶组织表现出显着的DNA断裂和H2 O2积累，并沿着上调与衰老相关的基因。突变体还表现出SIR2样基因OsSRT 1和OsSRT 2的表达降低和组蛋白H3K9乙酰化水平的增加。OsSRTs下调诱导衰老相关基因组蛋白H3K9乙酰化这些结果表明，在NAD补救途径的缺陷，可以触发过早的叶片衰老，由于衰老相关基因的转录激活。
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 ofLeaf Tip Senescence 1(LTS1) in rice (Oryza sativa), a recessive mutation in the gene encodingO. sativanicotinate phosphoribosyltransferase (OsNaPRT1) in the NAD salvage pathway. A point mutation inOsNaPRT1leads to dwarfism and the withered leaf tip phenotype, and thelts1mutant displays early leaf senescence compared to the wild type. Leaf nicotinate and nicotinamide contents are elevated inlts1, while NAD levels are reduced. Leaf tissue oflts1exhibited significant DNA fragmentation and H2O2accumulation, along with up-regulation of genes associated with senescence. Thelts1mutant also showed reduced expression of SIR2-like genes (OsSRT1andOsSRT2) and increased acetylation of histone H3K9. Down-regulation ofOsSRTsinduced 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.