Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore City, 117543, Singapore.
New Phytol. 2019 Feb;221(3):1369-1386. doi: 10.1111/nph.15464. Epub 2018 Oct 5.
Class I TREHALOSE-PHOSPHATE-SYNTHASE (TPS) genes affect salinity tolerance and plant development. However, the function of class IITPS genes and their underlying mechanisms of action are unknown. We report the identification and functional analysis of a rice class IITPS gene (OsTPS8). The ostps8 mutant was characterised by GC-MS analysis, an abscisic acid (ABA) sensitivity test and by generating transgenic lines. To identify the underlying mechanism, gene expression analyses, genetic complementation and examination of suberin deposition in the roots were conducted. The ostps8 mutant showed salt sensitivity, ABA sensitivity and altered agronomic traits compared to the wild-type (WT), which could be rescued upon complementation. The dsRNAi line phenocopied the mutant, while the overexpression lines exhibited enhanced salt tolerance. The ostps8 mutant showed significantly reduced soluble sugars, Casparian bands and suberin deposition in the roots compared to the WT and overexpression lines. The mutant also showed downregulation of SAPKs (rice SnRK2s) and ABA-responsive genes. Furthermore, ostps8pUBI::SAPK9 rescued the salt-sensitive phenotype of ostps8. Our results suggest that OsTPS8 may regulate suberin deposition in rice through ABA signalling. Additionally, SAPK9-mediated regulation of altered ABA-responsive genes helps to confer salinity tolerance. Overexpression of OsTPS8 was adequate to confer enhanced salinity tolerance without any yield penalty, suggesting its usefulness in rice genetic improvement.
I 类海藻糖-6-磷酸合酶（TPS）基因影响盐度耐受性和植物发育。然而，I 类 TPS 基因的功能及其作用机制尚不清楚。我们报告了一个水稻 I 类 TPS 基因（OsTPS8）的鉴定和功能分析。通过 GC-MS 分析、脱落酸（ABA）敏感性测试和生成转基因系对 ostps8 突变体进行了表征。为了确定潜在的机制，进行了基因表达分析、遗传互补和根中蜡质沉积的检查。与野生型（WT）相比，ostps8 突变体表现出盐敏感性、ABA 敏感性和改变的农艺性状，这些性状可以通过互补得到挽救。dsRNAi 系表现出与突变体相似的表型，而过表达系则表现出增强的耐盐性。与 WT 和过表达系相比，ostps8 突变体的可溶性糖、凯氏带和根中的蜡质沉积明显减少。突变体还表现出 SAPKs（水稻 SnRK2s）和 ABA 响应基因的下调。此外，ostps8pUBI::SAPK9 挽救了 ostps8 的盐敏感表型。我们的结果表明，OsTPS8 可能通过 ABA 信号调节水稻中蜡质的沉积。此外，SAPK9 介导的改变的 ABA 响应基因的调节有助于赋予耐盐性。过表达 OsTPS8 足以赋予增强的耐盐性而不影响产量，这表明其在水稻遗传改良中的有用性。
