Ma Lanxin, Gao Qian, Liu Yongbin, He Shun, Xiang Haiying, Wu Mingzhu, Xu Xin, Luo Zhaopeng, Li Hongguang, Yang Jun, Wang Zhong
China Tobacco Gene Research Center, Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou, 450001, China.
Yunnan Key Laboratory of Tobacco Chemistry, R&D Center of China Tobacco Yunnan Industrial Co. Ltd., Kunming, 650202, China.
Plant J. 2025 Jun;122(5):e70245. doi: 10.1111/tpj.70245.
Abscisic acid (ABA) and ethylene signaling activate the NAC transcription factor NAP, accelerating plant leaf senescence. NAP promotes the synthesis of ABA and ethylene in turn. However, the crosstalk between ABA and ethylene in regulating leaf senescence, and whether NAP plays roles in mediating the crosstalk between these two hormones, still remains to be further clarified. This study identified the tobacco NtNAP and verified its conserved roles in promoting leaf senescence. ChIP assay, transactivation analysis, yeast one-hybrid assay, and electrophoretic mobility shift assay demonstrated that NtNAP directly bound to the promoters and activated the expression of NtACS8a, NtACO4-6, NtPYL4b, and NtSnRK2.6b genes in vivo and in vitro, leading to the production of ethylene and enhanced ABA signaling in tobacco. Blocking ethylene synthesis by AVG treatment or knockout of ACS and ACO delayed ABA-induced leaf senescence in both tobacco and Arabidopsis, while loss of function of PYL4 and SnRK2.6 relieved leaf senescence induced by ACC treatment, which together validated the crosstalk between ABA and ethylene in regulating leaf senescence. Moreover, ABA promoted the production of ethylene in a NAP-dependent manner, and blocking NAP-induced ethylene production relieved leaf senescence caused by ABA treatment in both tobacco and Arabidopsis. Meanwhile, NAP also mediated the enhancement of ABA signaling induced by ACC treatment. Our results revealed a new mechanism by which NAP promotes leaf senescence through synergistic ABA and ethylene signaling.
脱落酸（ABA）和乙烯信号激活NAC转录因子NAP，加速植物叶片衰老。NAP反过来促进ABA和乙烯的合成。然而，ABA与乙烯在调控叶片衰老过程中的相互作用，以及NAP是否在介导这两种激素的相互作用中发挥作用，仍有待进一步阐明。本研究鉴定了烟草NtNAP，并验证了其在促进叶片衰老中的保守作用。染色质免疫沉淀分析、反式激活分析、酵母单杂交分析和电泳迁移率变动分析表明，NtNAP在体内和体外直接结合到启动子上，并激活NtACS8a、NtACO4 - 6、NtPYL4b和NtSnRK2.6b基因的表达，从而导致烟草中乙烯的产生和ABA信号的增强。通过AVG处理阻断乙烯合成或敲除ACS和ACO，均可延迟烟草和拟南芥中ABA诱导的叶片衰老，而PYL4和SnRK2.6功能丧失则缓解了ACC处理诱导的叶片衰老，这些结果共同验证了ABA与乙烯在调控叶片衰老中的相互作用。此外，ABA以依赖NAP的方式促进乙烯的产生，阻断NAP诱导的乙烯产生可缓解烟草和拟南芥中ABA处理引起的叶片衰老。同时，NAP还介导了ACC处理诱导的ABA信号增强。我们的结果揭示了一种新的机制，即NAP通过协同ABA和乙烯信号促进叶片衰老。
