Plant Cell∣中科院大豆分子設計育種重點實驗室卜慶雲課題組發文揭示水稻角質層蠟的生物合成新途徑

02-02

2017年12月13日Plant Cell在線文章，該文章為中科院東北地理與農業生態研究所大豆分子設計育種重點實驗室卜慶雲課題組發表，文章揭示水稻中DHS 可以通過降解ROC4來負調控角質層蠟的生物合成，這為水稻抗旱品種的設計育種提供了基礎。

原題目為：

The E3 Ligase DROUGHT HYPERSENSITIVE Negatively Regulates Cuticular Wax Biosynthesis by Promoting the Degradation of Transcription Factor ROC4 in Rice

摘要：

角質層蠟在保護植物免受環境壓力（特別是乾旱脅迫）方面起著至關重要的作用。涉及蠟生物合成的許多編碼酶和轉錄因子的基因已經被鑒定了，但是其翻譯後調控機制仍知之甚少。這裡，我們闡釋了一個RING類型的蛋白質DHS，它是水稻蠟生物合成的關鍵調節子。與野生型相比，DHS過表達植物中的角質層蠟含量顯著減少，而dhs突變體中的蠟含量增加，這導致對乾旱脅迫相反的響應。DHS表現出E3泛素連接酶活性並與蛋白ROC4相互作用。 ROC4過表達植物和roc4突變體的分析表明，ROC4正調控角質層蠟生物合成和乾旱脅迫響應。ROC4在體內被泛素化並且受到泛素/26S蛋白酶體（UPS）介導的降解。DHS促進ROC4降解，但在dhs突變體中延遲。ROC4作用於DHS的下游，Os-BDG是DHS-ROC4級聯的直接下游靶標。這些結果表明DHS通過促進ROC4的降解來負調控蠟的生物合成，並且提示DHS和ROC4是耐旱水稻栽培品種工程的有價值的靶標。

Abstract：

Cuticular wax plays crucial roles in protecting plants from environmental stresses, particularly drought stress. Many enzyme-encoding genes and transcription factors involved in wax biosynthesis have been identified, but the underlying posttranslational regulatory mechanisms are poorly understood. Here, we demonstrate that DROUGHT HYPERSENSITIVE (DHS), encoding a Really Interesting New Gene (RING)-type protein, is a critical regulator of wax biosynthesis in rice (Oryza sativa). The cuticular wax contents were significantly reduced in DHS overexpression plants but increased in dhs mutants compared to the wild type, which resulted in a response opposite that of drought stress. DHS exhibited E3 ubiquitin ligase activity and interacted with the homeodomain-leucine zipper IV protein ROC4. Analysis of ROC4 overexpression plants and roc4 mutants indicated that ROC4 positively regulates cuticular wax biosynthesis and the drought stress response. ROC4 is ubiquitinated in vivo and subjected to ubiquitin/26S proteasome (UPS)-mediated degradation. ROC4 degradation was promoted by DHS but delayed in dhs mutants. ROC4 acts downstream of DHS, and Os-BDG is a direct downstream target of the DHS-ROC4 cascade. These results suggest a mechanism whereby DHS negatively regulates wax biosynthesis by promoting the degradation of ROC4, and they suggest that DHS and ROC4 are valuable targets for the engineering of drought-tolerant rice cultivars.

每日一詞
cuticular
英[kju:t?kj?l?]
美[kju:t?kj?l?]

adj. 表皮的;角質層的
[例句]Skin atrophy affects cuticular, derma and subcutaneous tissue.
皮膚萎縮波及表皮、真皮和皮下組織。
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