Environ Exp Bot：河南農業大學丨水稻根部響應缺氧的分子機制研究（附NMT實驗體系）

NMT是基因功能的活體檢測技術，已被103位諾貝爾獎得主所在單位，及北大、清華、中科院使用。

期刊：Environmental and Experimental Botany

主題：水稻根部響應缺氧的分子機制研究

標題：Comparative morphological and transcriptomic responses of lowland and upland rice to root-zone hypoxia

影響因子：3.712

檢測指標：IAA、O2流速

檢測樣品：水稻（低地和高地兩種）距根尖0,200, 300, 600, 900, 1200, 1500, 2500 μm

IAA、O2流速流實驗處理方法：

10日齡幼苗分別在充足氧（4.5-6.0 mg·L?1）和缺氧（0.9-2.1 mg·L?1）條件下培養5d

IAA、O2流速流實驗測試液成份：
0.1mM KCl, 0.1mM CaCl2, 0.1mM MgCl2, 0.3mM MES, pH 5.5

作者：河南農業大學趙全志、辛澤毓、劉娟

英文摘要

Lowland and upland rice, as for two ecotypes, that have been exhibited different tolerance levels under hypoxia conditions. However, the molecular mechanisms underlying rice root hypoxia tolerance between them are not fully understood.

This study was performed to assess the morphological, physiological and transcriptional changes of roots in one lowland rice YueFu (YF) and one upland rice IRAT109 (IR) genotype. A morpho-physiological analysis revealed that compared to IR, YF showed less reduction of root length, root and shoot biomass, formed more aerenchyma in the root, and kept more oxygen influxes in root under hypoxia conditions. Indole-3-acetic acid (IAA) fluxes patterns exhibited a different response to hypoxia in YF and IR.

The contents of IAA, ethylene and hydrogen peroxide were significantly increased in YF and IR, but nitric oxide significantly increased only in YF under hypoxic conditions. Subsequently, transcriptome analysis revealed that more differentially expressed genes (DEGs) were identified to respond to hypoxia in YF than IR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that DEGs in both genotypes enriched in energy metabolism, aerenchyma formation, reactive oxygen species, and cell wall modification, whereas more related DEGs in YF significantly enriched in these pathways than IR. The specific DEGs in YF especially enriched in phytohormone metabolism and signaling, such as auxin, jasmonic acid, and ethylene, but the specific DEGs in IR especially enriched in photosynthesis. All these results demonstrate that YF is more tolerant to hypoxia than IR, and elucidate some specific mechanisms underlying the differential hypoxia tolerance in lowland and upland rice.

This study has provided valuable candidate genes for genetic improvement of rice in adapting to hypoxia stress.

中文摘要（谷歌機翻）

就兩種生態型而言，低陸和旱稻在低氧條件下表現出不同的耐受水平。然而，它們之間的水稻根缺氧耐受性的分子機制尚不完全清楚。

這項研究的目的是評估一種低陸稻悅富（YF）和一種陸稻IRAT109（IR）基因型的根的形態，生理和轉錄變化。形態生理學分析表明，與IR相比，YF在低氧條件下顯示的根長，根和莖生物量減少減少，在根中形成更多的氣孔，并保持更多的氧流入。吲哚-3-乙酸（IAA）通量模式在YF和IR中顯示出對缺氧的不同響應。

在低氧條件下，IAF，乙烯和過氧化氫的含量在YF和IR中顯著增加，而一氧化氮僅在YF中顯著增加。隨后，轉錄組分析顯示，與IR相比，鑒定出更多的差異表達基因（DEG）對YF缺氧有反應。基因本體論（GO）和《京都基因與基因組百科全書》（KEGG）分析表明，兩種基因型的DEG均富含能量代謝，通氣組織形成，活性氧種類和細胞壁修飾，而YF中更多相關的DEG則顯著豐富了這些途徑比紅外線YF中的特定DEGs尤其富含植物激素代謝和信號傳導，例如生長素，茉莉酸和乙烯，而IR中的特定DEGs尤其富含光合作用。所有這些結果表明，YF比IR更耐缺氧，并闡明了低陸稻和旱稻差異耐缺氧性的某些特定機制。

該研究為水稻遺傳適應低氧脅迫提供了有價值的候選基因。

結果表明：在氧氣充足（Aer）的條件下，分生區吸收O2比較劇烈。YF（低地品種）和IR（高地品種）在300μm處吸收的O2最多，其流速值分別達到79.14 pmol·cm?2·s?1和83.72 pmol·cm?2·s?1，而在缺氧（Hyp）條件下分別為44.77 pmol·cm?2·s?1和40.08 pmol·cm?2·s?1；IR明顯降低的更多一些。這說明，分生區是水稻根部感受氧的關鍵區域，IR對缺氧條件更加敏感。

根分生區同時也是IAA較為敏感的區域。缺氧條件下，除IR的300μm處之外，兩種水稻均表現為吸收IAA。氧氣充足時，YF和IR在600μm處的IAA吸收速率分別為29,740 fmol·cm?2·s-1和35,092 fmol·cm?2·s-1；而在缺氧條件下分別為8864 fmol·cm?2·s-1和5441 fmol·cm?2·s-1。結合IAA含量測定結果，發現缺氧促使根部積累IAA。這說明生長素參與了缺氧條件下根系發育的調控過程。