Rice, a staple food with tropical/subtropical origination, is susceptible to cold stress, one of the major constraints on its yield and distribution. Asian cultivated rice consists of two subspecies with diverged chilling tolerance to adapt to different environments. The mechanism underlying this divergence remains obscure with a few known factors, including membrane protein CHILLING-TOLERANCE DIVERGENCE 1 (COLD1). Here, we reveal a vitamin E-vitamin K1 sub-network responsible for chilling tolerance divergence through global analyses. Rice genome regions responsible for tolerance divergence are identified with chromosome segment substitution lines (CSSLs). Comparative transcriptomic and metabolomic analysis of chilling-tolerant CSSL4-1 and parent lines uncovered a vitamin E-vitamin K1 sub-network in chloroplast with tocopherol (vitamin E) mediating chloroplast-to-nucleus signaling. COLD1, located in the substitution segment in CSSL4-1, is confirmed as its upstream regulator by transgenic material analysis. Our work uncovers a pathway downstream of COLD1, through which rice modulates chilling tolerance for thermal adaptation, with potential utility in crop improvement.
溫度是影響水稻品種形成和地域分布的主要環(huán)境因子。亞洲栽培稻主要分為粳稻和秈稻，粳稻低溫耐受性較強，主要分布于我國北部和東北部，而秈稻低溫耐受性較弱，主要分布于我國華南和淮河以南的熱帶/亞熱帶地區(qū)。COLD1是水稻低溫感受器，在秈粳稻之間存在明顯差異，COLD1中單個核苷酸變化可明顯地改變水稻的耐寒性。然而，低溫感受器下游信號通路眾多，究竟哪些調控途徑在秈粳稻耐寒性差異形成中發(fā)揮關鍵作用尚不清楚。本文報道了水稻低溫感受器COLD1下游的維生素E-K1網絡，揭示了COLD1調控的水稻耐寒新機制。
通過多組學分析發(fā)現(xiàn)維生素E-維生素K1子網絡是COLD1下游傳導通路，并是秈粳稻低溫耐受性差異形成的關鍵調控點。他們從粳稻日本晴為供體的秈稻93-11單片段代換系入手，選取低溫耐受性提升至近粳稻水平的代換系，基因組序列分析表明COLD1位于代換片段區(qū)域；轉錄組分析發(fā)現(xiàn)代換系與日本晴中低溫應答變化規(guī)律相似的通路集中于泛醌/萜醌代謝網絡（包括維生素合成途徑）；代謝組分析進一步聚焦到葉綠體中維生素E和維生素K1代謝途徑；轉錄/代謝雙組學相關性網絡分析表明維生素E-維生素K1亞網絡是代換系低溫耐受性提升的核心調控點。轉基因材料分析驗證維生素E-維生素K1亞網絡確為COLD1下游途徑。
綜上所述，該研究通過多組學與遺傳材料相結合的分析手段揭示了低溫信號被植物感知后的下游傳導途徑，挖掘了秈粳不同低溫耐受性形成的關鍵調控點，為水稻耐寒分子育種奠定理論基礎并供可操作的靶點和材料。