State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China.
Department of Science and Technology of Shaanxi Province, Hybrid Rapeseed Research Center of Shaanxi Province, Yangling 712100, Shaanxi, China.
Plant Cell. 2024 Sep 3;36(9):3498-3520. doi: 10.1093/plcell/koae163.
The brassinosteroid (BR) receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1) plays a critical role in plant growth and development. Although much is known about how BR signaling regulates growth and development in many crop species, the role of StBRI1 in regulating potato (Solanum tuberosum) tuber development is not well understood. To address this question, a series of comprehensive genetic and biochemical methods were applied in this investigation. It was determined that StBRI1 and Solanum tuberosum PLASMA MEMBRANE (PM) PROTON ATPASE2 (PHA2), a PM-localized proton ATPase, play important roles in potato tuber development. The individual overexpression of StBRI1 and PHA2 led to a 22% and 25% increase in tuber yield per plant, respectively. Consistent with the genetic evidence, in vivo interaction analysis using double transgenic lines and PM H+-ATPase activity assays indicated that StBRI1 interacts with the C-terminus of PHA2, which restrains the intramolecular interaction of the PHA2 C-terminus with the PHA2 central loop to attenuate autoinhibition of PM H+-ATPase activity, resulting in increased PHA2 activity. Furthermore, the extent of PM H+-ATPase autoinhibition involving phosphorylation-dependent mechanisms corresponds to phosphorylation of the penultimate Thr residue (Thr-951) in PHA2. These results suggest that StBRI1 phosphorylates PHA2 and enhances its activity, which subsequently promotes tuber development. Altogether, our results uncover a BR-StBRI1-PHA2 module that regulates tuber development and suggest a prospective strategy for improving tuberous crop growth and increasing yield via the cell surface-based BR signaling pathway.
油菜素内酯（BR）受体 BRASSINOSTEROID-INSENSITIVE 1（BRI1）在植物生长和发育中起着关键作用。尽管人们已经了解了 BR 信号如何调节许多作物物种的生长和发育，但 StBRI1 在调节马铃薯（Solanum tuberosum）块茎发育中的作用还不是很清楚。为了解决这个问题，本研究采用了一系列全面的遗传和生化方法。研究结果表明，StBRI1 和 Solanum tuberosum PLASMA MEMBRANE（PM）PROTON ATPASE2（PHA2），一种 PM 定位质子 ATPase，在马铃薯块茎发育中发挥重要作用。StBRI1 和 PHA2 的单独过表达分别导致植株的块茎产量增加了 22%和 25%。与遗传证据一致，使用双转基因系进行体内相互作用分析和 PM H+-ATPase 活性测定表明，StBRI1 与 PHA2 的 C 端相互作用，这抑制了 PHA2 C 端与 PHA2 中心环的分子内相互作用，从而减弱 PM H+-ATPase 活性的自动抑制，导致 PHA2 活性增加。此外，涉及磷酸化依赖机制的 PM H+-ATPase 自动抑制的程度与 PHA2 中倒数第二个 Thr 残基（Thr-951）的磷酸化相对应。这些结果表明，StBRI1 磷酸化 PHA2 并增强其活性，从而促进块茎发育。总之，我们的研究结果揭示了一个 BR-StBRI1-PHA2 模块，该模块调节块茎发育，并为通过基于细胞表面的 BR 信号通路改善块茎作物生长和提高产量提供了一种有前景的策略。
