Nitrogen deficiency induces leaf senescence. However, whether or how nitrate might affect this process remains to be investigated. Here, we report an interesting finding that nitrate-- instead of nitrogen--starvation ...Nitrogen deficiency induces leaf senescence. However, whether or how nitrate might affect this process remains to be investigated. Here, we report an interesting finding that nitrate-- instead of nitrogen--starvation induced early leaf senescence in nrtf.5 mutant, and present genetic and physiological data demon-strating that nitrate starvation-induced leaf senescence is suppressed by NRTI.5. NRT1.5 suppresses the senescence process dependent on its function from roots, but not the nitrate transport function. Further analyses using nrt1.5 single and nial nia2 nrt1.5-4 triple mutant showed a negative correlation between nitrate concentration and senescence rate in leaves. Moreover, when exposed to nitrate starvation, foliar potassium level decreased in nrt1.5, but adding potassium could essentially restore the early leaf senescence phenotype of nrt1.5 plants. Nitrate starvation also downregulated the expression of HAK5, RAP2.11, and ANN1 in nrt1.5 roots, and appeared to alter potassium level in xylem sap from nrt1.5. These data suggest that NRT1.5 likely perceives nitrate starvation-derived signals to prevent leaf senescence by facilitating foliar potassium accumulation.展开更多
基金This work was supported by the National Science Foundation of China （Grants 31325003, 31421093）, the Ministry of Agriculture of China （Grant 2014ZX08009-003-005）, and partially by the SA-SIBS Scholarship program.ACKNOWLEDGMENTS We thank Dr. Yi-Fang Tsay （Institute of Molecular Biology, Academia Sinica） for kindly providing the seeds of nrtl.5-1 and ch11-5 Dr. YongFei Wang （Shanghai Institutes for Biological Sciences） for kindly providing the seeds of slah2 and slah3-4 and Dr. Remy Gibrat （Universite Montpellier 2） for kindly providing the seeds of naxt-RNAi. No conflict of interest declared,
文摘Nitrogen deficiency induces leaf senescence. However, whether or how nitrate might affect this process remains to be investigated. Here, we report an interesting finding that nitrate-- instead of nitrogen--starvation induced early leaf senescence in nrtf.5 mutant, and present genetic and physiological data demon-strating that nitrate starvation-induced leaf senescence is suppressed by NRTI.5. NRT1.5 suppresses the senescence process dependent on its function from roots, but not the nitrate transport function. Further analyses using nrt1.5 single and nial nia2 nrt1.5-4 triple mutant showed a negative correlation between nitrate concentration and senescence rate in leaves. Moreover, when exposed to nitrate starvation, foliar potassium level decreased in nrt1.5, but adding potassium could essentially restore the early leaf senescence phenotype of nrt1.5 plants. Nitrate starvation also downregulated the expression of HAK5, RAP2.11, and ANN1 in nrt1.5 roots, and appeared to alter potassium level in xylem sap from nrt1.5. These data suggest that NRT1.5 likely perceives nitrate starvation-derived signals to prevent leaf senescence by facilitating foliar potassium accumulation.
