Gao Cuimin, Ding Lei, Li Yingrui, Chen Yupei, Zhu Jingwen, Gu Mian, Li Yong, Xu Guohua, Shen Qirong, Guo Shiwei
College of Resources and Environmental Sciences, Nanjing Agricultural University, National Engineering Research Center for Organic-based Fertilizers, Nanjing 210095, China.
Crop Physiology and Production Center, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
Funct Plant Biol. 2017 Apr;44(4):430-442. doi: 10.1071/FP16258.
Ethylene increases root cortical aerenchyma formation in maize (Zea mays L.), rice (Oryza sativa L.) and other species. To further investigate the effects of nitrate, ammonium and water stress on ethylene production and aerenchyma formation in roots, two lowland rice cultivars (Shanyou 63, hybrid indica, and Yangdao 6, inbred indica) were cultured hydroponically with 10% (w/v) polyethylene glycol to simulate water stress. Water stress decreased shoot biomass, stomatal conductivity and leaf water potential in cultivars fed with nitrate but not with ammonium. Water stress induced more aerenchyma formation in cultivars fed with nitrate rather than ammonium, and increased cortical aerenchyma was found in Yangdao 6. Endogenous ethylene production by roots increased significantly under water stress in plants fed with nitrate rather than ammonium. Exogenous ethylene stimulated root cortical aerenchyma formation. Expression of the ethylene biosynthesis gene 1-aminocyclo-propane-1-carboxylic acid (ACC) synthase (ACS5) was greater in roots fed with nitrate rather than ammonium in the presence and absence of water stress. The expression of ethylene signalling pathway genes involved in programmed cell death (lesion-simulating disease (L.S.D.)1.1 and L.S.D.2; enhanced disease susceptibility (EDS) and phytoalexin-deficient (PAD4)) were regulated by the N form and water stress. In plants of cultivars fed with ammonium, L.S.D.1.1 expression increased under water stress, whereas L.S.D.2, EDS and PAD4 expression decreased. In conclusion, nitrate increases ethylene production and cortical aerenchyma formation in roots of water-stressed lowland rice. However, ammonium increased L.S.D.1.1 expression in water-stressed roots, and decreased ACS5, EDS and PAD4 expression, which would inhibit ethylene production and aerenchyma formation.
乙烯可促进玉米（Zea mays L.）、水稻（Oryza sativa L.）及其他物种根皮层通气组织的形成。为进一步研究硝酸盐、铵盐和水分胁迫对根系乙烯产生及通气组织形成的影响，采用10%（w/v）聚乙二醇水培两个低地水稻品种（汕优63，杂交籼稻；扬稻6号，常规籼稻）以模拟水分胁迫。水分胁迫降低了供氮而非供铵品种的地上部生物量、气孔导度和叶片水势。水分胁迫诱导供氮品种而非供铵品种形成更多通气组织，且在扬稻6号中发现皮层通气组织增加。水分胁迫下，供氮而非供铵植株的根系内源乙烯产量显著增加。外源乙烯刺激根皮层通气组织的形成。在有或无水分胁迫的情况下，乙烯生物合成基因1-氨基环丙烷-1-羧酸（ACC）合酶（ACS5）在供氮而非供铵的根系中表达量更高。参与程序性细胞死亡的乙烯信号通路基因（类病变蛋白（L.S.D.）1.1和L.S.D.2；感病增强蛋白（EDS）和植物抗毒素缺陷蛋白（PAD4））的表达受氮形态和水分胁迫的调控。在供铵品种的植株中，水分胁迫下L.S.D.1.1表达增加，而L.S.D.2、EDS和PAD4表达降低。总之，硝酸盐增加水分胁迫下低地水稻根系乙烯的产生和皮层通气组织的形成。然而，铵盐增加了水分胁迫下根系中L.S.D.1.1的表达，降低了ACS5、EDS和PAD4的表达，这将抑制乙烯的产生和通气组织的形成。
