Lin Qingfang, Wang Song, Dao Yihang, Wang Jianyong, Wang Kai
Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu, China.
J Exp Bot. 2020 Jul 6;71(14):4285-4297. doi: 10.1093/jxb/eraa173.
Transpiration occurs through stomata. The alteration of stomatal apertures in response to drought stress is an important process associated with water use efficiency (WUE). Trehalose-6-phosphate phosphatase (TPP) family genes have been reported to participate in adjustment of stomatal aperture. However, there have been no reports of the trehalose metabolism pathway genes improving WUE, and the upstream signalling pathway modulating these genes is not clear. Here, we demonstrate that a member of the TPP gene family, AtTPPI, confers drought resistance and improves WUE by decreasing stomatal apertures and improving root architecture. The reduced expression of AtTPPI caused a drought-sensitive phenotype, while its overexpression significantly increased drought tolerance. Abscisic acid (ABA)-induced stomatal closure experiments confirmed that AtTPPI mutation increased the stomatal aperture compared with that of wild-type plants; in contrast, overexpression plants had smaller stomatal apertures than those of wild-type plants. Moreover, AtTPPI mutation also caused stunted primary root length and compromised auxin transport, while overexpression plants had longer primary root lengths. Yeast one-hybrid assays showed that ABA-responsive element-binding factor1 (ABF1), ABF2, and ABF4 directly regulated AtTPPI expression. In summary, the way in which AtTPPI responds to drought stress suggests that AtTPPI-mediated stomatal regulation is an important mechanism to cope with drought stress and improve WUE.
蒸腾作用通过气孔进行。气孔开度响应干旱胁迫而发生的改变是一个与水分利用效率（WUE）相关的重要过程。据报道，海藻糖-6-磷酸磷酸酶（TPP）家族基因参与气孔开度的调节。然而，尚无关于海藻糖代谢途径基因提高水分利用效率的报道，且调控这些基因的上游信号通路尚不清楚。在此，我们证明TPP基因家族的一个成员AtTPPI通过减小气孔开度和改善根系结构赋予植物抗旱性并提高水分利用效率。AtTPPI表达降低导致干旱敏感表型，而其过表达显著提高了耐旱性。脱落酸（ABA）诱导的气孔关闭实验证实，与野生型植物相比，AtTPPI突变体增加了气孔开度；相反，过表达植株的气孔开度比野生型植株小。此外，AtTPPI突变还导致主根长度发育不良和生长素运输受损，而过表达植株的主根长度更长。酵母单杂交试验表明，ABA响应元件结合因子1（ABF1）、ABF2和ABF4直接调控AtTPPI的表达。总之，AtTPPI对干旱胁迫的响应方式表明，AtTPPI介导的气孔调节是应对干旱胁迫和提高水分利用效率的重要机制。
