Boron deficiency-induced root growth inhibition is mediated by brassinosteroid signaling regulation in Arabidopsis
Boron deficiency-induced root growth inhibition is mediated by brassinosteroid signaling regulation in Arabidopsis
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拟南芥中缺硼引起的根生长抑制是由油菜素类固醇信号调节介导的
DOI：
10.1111/tpj.15311
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Fangsen Xu
中科院分区：
文献类型：
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作者：
Cheng Zhang;Mingliang He;Sheliang Wang;Liuyang Chu;Chuang Wang;Ningmei Yang;Guangda Ding;Hongmei Cai;Lei Shi;Fangsen Xu
油菜素类固醇（BR）是参与控制根发育的关键植物激素。硼（B）是植物必需的微量营养素，缺硼条件下根系生长会迅速受到抑制。然而，这种抑制作用的机制仍不清楚。在这里，我们在生理、遗传、分子/细胞生物学和转录组水平上确定了 B 缺乏背后的 BR 相关过程，并发现了强有力的证据表明 B 缺乏可以影响 BR 生物合成和信号传导，从而改变根系生长。 RNA 测序分析揭示了 BR 调节基因和 B 缺乏反应基因之间存在很强的共同调节作用。我们发现BR受体突变体bri1-119和bri1-301对B供应减少更不敏感，而功能获得突变体bes1-D和pBZR1-bzr1-D对低B胁迫表现出不敏感性。在B缺乏条件下，外源24-表油菜素内酯挽救了对根生长的抑制，而BR生物合成抑制剂油菜素唑的应用加剧了这种抑制作用。与 B 充足条件相比，BES1 的核定位信号在低 B 条件下减少。我们进一步发现 B 缺乏阻碍了芸苔素内酯的积累，从而下调 BR 信号传导并调节根伸长，这可能是通过减少 BR6ox1 和 BR6ox2 mRNA 水平来实现的。综上所述，我们的结果揭示了 BR 信号传导在 B 缺乏下根伸长中的作用。
Brassinosteroids (BRs) are pivotal phytohormones involved in the control of root development. Boron (B) is an essential micronutrient for plants, and root growth is rapidly inhibited under B deficiency conditions. However, the mechanisms underlying this inhibition are still unclear. Here, we identified BR‐related processes underlying B deficiency at the physiological, genetic, molecular/cell biological and transcriptomic levels and found strong evidence that B deficiency can affect BR biosynthesis and signalling, thereby altering root growth. RNA sequencing analysis revealed strong co‐regulation between BR‐regulated genes and B deficiency‐responsive genes. We found that the BR receptor mutantsbri1‐119andbri1‐301were more insensitive to decreased B supply, and the gain‐of‐function mutantsbes1‐DandpBZR1‐bzr1‐Dexhibited insensitivity to low‐B stress. Under B deficiency conditions, exogenous 24‐epibrassinolide rescued the inhibition of root growth, and application of the BR biosynthesis inhibitor brassinazole exacerbated this inhibitory effect. The nuclear‐localised signal of BES1 was reduced under low‐B conditions compared with B sufficiency conditions. We further found that B deficiency hindered the accumulation of brassinolide to downregulate BR signalling and modulate root elongation, which may occur through a reduction inBR6ox1andBR6ox2mRNA levels. Taken together, our results reveal a role of BR signalling in root elongation under B deficiency.