Kong Xiangqiang, Luo Zhen, Dong Hezhong, Eneji A Egrinya, Li Weijiang
Cotton Research Center, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China.
Cotton Research Center, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
J Exp Bot. 2016 Apr;67(8):2247-61. doi: 10.1093/jxb/erw026. Epub 2016 Feb 8.
Non-uniform root salinity increases the Na(+)efflux, water use, and growth of the root in non-saline side, which may be regulated by some form of signaling induced by the high-salinity side. However, the signaling and its specific function have remained unknown. Using a split-root system to simulate a non-uniform root zone salinity in Gossypium hirsutum L., we showed that the up-regulated expression of sodium efflux-related genes (SOS1, SOS2, PMA1, and PMA2) and water uptake-related genes (PIP1 and PIP2) was possibly involved in the elevated Na(+) efflux and water use in the the roots in the non-saline side. The increased level of indole acetic acid (IAA) in the non-saline side was the likely cause of the increased root growth. Also, the abscisic acid (ABA) and H2O2 contents in roots in the non-saline side increased, possibly due to the increased expression of their key biosynthesis genes, NCED and RBOHC, and the decreased expression of ABA catabolic CYP707A genes. Exogenous ABA added to the non-saline side induced H2O2 generation by up-regulating the RBOHC gene, but this was decreased by exogenous fluridone. Exogenous H2O2 added to the non-saline side reduced the ABA content by down-regulating NCED genes, which can be induced by diphenylene iodonium (DPI) treatment in the non-saline side, suggesting a feedback mechanism between ABA and H2O2.Both exogenous ABA and H2O2 enhanced the expression of SOS1, PIP1;7 ,PIP2;2, and PIP2;10 genes, but these were down-regulated by fluridone and DPI, suggesting that H2O2 and ABA are important signals for increasing root Na(+) efflux and water uptake in the roots in the non-saline side.
根系盐分不均增加了非盐侧根系的Na⁺外流、水分利用和生长，这可能受高盐侧诱导的某种信号调节。然而，该信号及其具体功能尚不清楚。利用分根系统模拟陆地棉根系盐分不均，我们发现钠外流相关基因（SOS1、SOS2、PMA1和PMA2）和水分吸收相关基因（PIP1和PIP2）的表达上调可能参与了非盐侧根系Na⁺外流和水分利用的增加。非盐侧吲哚乙酸（IAA）水平的升高可能是根系生长增加的原因。此外，非盐侧根系中的脱落酸（ABA）和H₂O₂含量增加，可能是由于其关键生物合成基因NCED和RBOHC的表达增加以及ABA分解代谢CYP707A基因的表达降低所致。向非盐侧添加外源ABA通过上调RBOHC基因诱导H₂O₂生成，但外源氟啶酮可降低这种生成。向非盐侧添加外源H₂O₂通过下调NCED基因降低ABA含量，在非盐侧用二苯基碘鎓（DPI）处理可诱导该基因，这表明ABA和H₂O₂之间存在反馈机制。外源ABA和H₂O₂均增强了SOS1、PIP1;7、PIP2;2和PIP2;10基因的表达，但氟啶酮和DPI可下调这些基因的表达，表明H₂O₂和ABA是增加非盐侧根系Na⁺外流和水分吸收的重要信号。
