背景回顾：Cold stress is a key environmental constraint that dramatically affects the growth, productivity, and quality of tomato (Solanum lycopersicum); however, the underlying molecular mechanisms of cold tolerance remain poorly understood. 

主要发现：In this study, we identified REDUCED CHLOROPLAST COVERAGE 2 (SlREC2) encoding a tetratricopeptide repeat (TPR) protein that positively regulates tomato cold tolerance. 

结果1-低温胁迫-REC2-ABA：Disruption of SlREC2 largely reduced abscisic acid (ABA) levels, photoprotection and the expression of C-REPEAT BINDING FACTOR (CBF) pathway genes in tomato plants under cold stress. 

结果2-REC2-NCED1-ABA-低温耐受性：ABA deficiency in the notabilis (not) mutant, which carries a mutation in 9-CIS-EPOXYCAROTENOID DIOXYGENASE 1 (SlNCED1), strongly inhibited the cold tolerance of SlREC2-silenced plants and empty vector control plants and resulted in a similar phenotype. In addition, foliar application of ABA rescued the cold tolerance of SlREC2-silenced plants, which confirms that SlNCED1-mediated ABA accumulation is required for SlREC2-regulated cold tolerance.  

结果3-REC2-BCH1b-ABA-低温耐受性：Strikingly, SlREC2 physically interacted with β-RING CAROTENE HYDROXYLASE 1b (SlBCH1b), a key regulatory enzyme in the xanthophyll cycle. Disruption of SlBCH1b severely impaired photoprotection, ABA accumulation and CBF-pathway gene expression in tomato plants under cold stress. 

结论：Taken together, this study reveals that SlREC2 interacts with SlBCH1b to enhance cold tolerance in tomato via integration of SlNCED1-mediated ABA accumulation, photoprotection, and the CBF-pathway, thus providing further genetic knowledge for breeding cold-resistant tomato varieties.

低温胁迫是一个关键的环境限制条件，严重影响了番茄的生长、产量和品质。但是，低温耐受性的潜在分子机制仍不清晰。本文中，作者鉴定到了一个三角形四肽重复（TPR）蛋白编码基因SlREC2，正向调控番茄的低温耐受性。SlREC2基因扰乱会大幅度降低低温胁迫下，番茄中的脱落酸水平、光保护以及CBF途径基因的表达。SlNCED1功能缺陷突变体not中的ABA缺陷会大幅度抑制SlREC2沉默和空载植株的低温耐受性，表现出类似的表型。另外，通过叶面喷施ABA能够恢复SlREC2沉默植株的低温耐受性，说明SlNCED1介导的ABA积累对于SlREC2调控的低温耐受性是必需的。有趣的是，SlREC2与SlBCH1b蛋白物理互作，后者是叶黄素循环的关键调控酶。SlBCH1b基因的扰乱会导致番茄在低温胁迫下光保护、ABA积累以及CBF途径基因表达的缺陷。综上，本文的研究结果揭示了SlREC2与SlBCH1b互作，通过整合SlNCED1介导的ABA积累、光保护和CBF途径，从而增强番茄的低温耐受性，为未来番茄的低温抗性育种提供参考。

** 李天来 **