背景回顾：Maize (Zea mays L.) is a cold-sensitive species that often faces chilling stress, which adversely affects growth and reproduction. 

提出问题：However, the genetic basis of low-temperature adaptation in maize remains unclear.

主要发现：Here, we demonstrate that natural variation in the type-A Response Regulator 1 (ZmRR1) gene leads to differences in chilling tolerance among maize inbred lines. 

结果1-ZmRR1发挥功能的关键位点：Association analysis reveals that InDel-35 of ZmRR1, encoding a protein harboring a mitogen-activated protein kinase (MPK) phosphorylation residue, is strongly associated with chilling tolerance. 

结果2-ZmRR1的调控蛋白ZmMPK8：ZmMPK8, a negative regulator of chilling tolerance, interacts with and phosphorylates ZmRR1 at Ser15. 

结果3-试验验证ZmRR1与ZmMPK8之间的关系：The deletion of a 45-bp region of ZmRR1 harboring Ser15 inhibits its degradation via the 26 S proteasome pathway by preventing its phosphorylation by ZmMPK8.

结果4-ZmRR1的下游作用基因：Transcriptome analysis indicates that ZmRR1 positively regulates the expression of ZmDREB1 and Cellulose synthase (CesA) genes to enhance chilling tolerance. 

结论：Our findings thus provide a potential genetic resource for improving chilling tolerance in maize.

 摘 要 

玉米是一种对于低温十分敏感的作物，经常会遭遇冷胁迫，影响玉米的生长和生殖。但是，玉米对于低温适应的遗传基础仍不清楚。本文中，作者发现玉米ZmRR1基因的天然变异导致了不同玉米自交系在对于冷胁迫响应方面的差异。关联分析显示，ZmRR1基因上编码丝裂原活化蛋白激酶MPK磷酸化残基的InDel-35与玉米的低温抗性存在较强的相关性。另外，低温抗性的负调控因子ZmMPK8能够与ZmRR1互作，并且磷酸化ZmRR1蛋白第15号位的丝氨酸。ZmRR1包含Ser15在内的45-bp缺失突变会阻止ZmMPK8对ZmRR1的磷酸化，从而抑制26S蛋白酶通路介导的ZmRR1蛋白降解。转录组分析显示ZmRR1能够正向调控ZmDREB1和CesA基因的表达，从而增强植株的低温抗性。本文的研究结果为玉米的低温抗性改良提供了潜在的遗传资源。

 通讯作者 

** 杨淑华 **