SummaryDrought is a critical issue in modern agriculture; therefore, there is a need to create crops with drought resilience. The complexity of plant responses to abiotic stresses, particularly in the field of brassinosteroid (BR) signalling, has been the subject of extensive research. In this study, we unveil compelling insights indicating that the BRASSINOSTEROID‐INSENSITIVE 1 (BRI1) receptor in Arabidopsis and Sorghum plays a critical role as a negative regulator of drought responses. Introducing untargeted mutation in the sorghum BRI1 receptor (SbBRI1) effectively enhances the plant's ability to withstand osmotic and drought stress. Through DNA Affinity Purification sequencing (DAP‐seq), we show that the sorghum BRI1‐EMS‐SUPPRESSOR 1 (SbBES1) transcription factor, a downstream player of the BR signalling, binds to a conserved G‐box binding motif, and it is responsible for regulating BR homeostasis, as its Arabidopsis ortholog AtBES1. We further characterized the drought tolerance of sorghum bri1 mutants and decipher SbBES1‐mediated regulation of phenylpropanoid pathway. Our findings suggest that SbBRI1 signalling serves a dual purpose: under normal conditions, it regulates lignin biosynthesis by SbBES1, but during drought conditions, BES1 becomes less active, allowing the activation of the flavonoid pathway. This adaptive shift improves the photosynthetic rate and photoprotection, reinforcing crop adaptation to drought.

中文翻译：

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油菜素类固醇受体 SbBRI1 的非靶向诱变通过改变高粱中的苯丙素代谢赋予干旱耐受性


摘要干旱是现代农业的一个关键问题；因此，需要培育具有抗旱能力的作物。植物对非生物胁迫反应的复杂性，特别是在油菜素类固醇（BR）信号传导领域，一直是广泛研究的主题。在这项研究中，我们揭示了令人信服的见解，表明拟南芥和高粱中的油菜素类固醇不敏感 1 (BRI1) 受体作为干旱反应的负调节因子发挥着关键作用。在高粱BRI1受体（SbBRI1）中引入非靶向突变可有效增强植物抵御渗透和干旱胁迫的能力。通过 DNA 亲和纯化测序 (DAP-seq)，我们发现高粱 BRI1-EMS-SUPPRESSOR 1 (SbBES1) 转录因子（BR 信号传导的下游参与者）与保守的 G-box 结合基序结合，并负责用于调节 BR 稳态，作为其拟南芥直系同源物 AtBES1。我们进一步表征了高粱 bri1 突变体的耐旱性，并破译了 SbBES1 介导的苯丙素途径的调节。我们的研究结果表明，SbBRI1 信号传导具有双重目的：在正常条件下，它通过 SbBES1 调节木质素生物合成，但在干旱条件下，BES1 活性降低，从而激活类黄酮途径。这种适应性转变提高了光合速率和光保护，增强了作物对干旱的适应能力。