College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China.
College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China.
Plant Physiol. 2023 May 2;192(1):648-665. doi: 10.1093/plphys/kiad085.
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. In this study, we identified REDUCED CHLOROPLAST COVERAGE 2 (SlREC2) encoding a tetratricopeptide repeat protein that positively regulates tomato cold tolerance. 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. 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. 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. 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.
冷胁迫是影响番茄（Solanum lycopersicum）生长、产量和品质的关键环境限制因素；然而，其耐冷性的潜在分子机制仍知之甚少。在本研究中，我们鉴定了 REDUCED CHLOROPLAST COVERAGE 2（SlREC2），它编码一个四肽重复蛋白，正向调控番茄的耐冷性。SlREC2 缺失在番茄植株中导致脱落酸（ABA）水平、光保护和 C-重复结合因子（CBF）途径基因的表达显著降低。在 notabilis（not）突变体中，携带 9-顺式-环氧类胡萝卜素双加氧酶 1（SlNCED1）突变，ABA 缺乏强烈抑制 SlREC2 沉默植株和空载体对照植株的耐冷性，并导致类似的表型。此外，叶片施用 ABA 挽救了 SlREC2 沉默植株的耐冷性，这证实了 SlNCED1 介导的 ABA 积累是 SlREC2 调控的耐冷性所必需的。引人注目的是，SlREC2 与β-环胡萝卜素羟化酶 1b（SlBCH1b）物理相互作用，SlBCH1b 是叶黄素循环中的关键调节酶。SlBCH1b 缺失严重损害了番茄植株在冷胁迫下的光保护、ABA 积累和 CBF 途径基因的表达。综上所述，本研究揭示了 SlREC2 通过整合 SlNCED1 介导的 ABA 积累、光保护和 CBF 途径与 SlBCH1b 相互作用，增强番茄的耐冷性，从而为培育耐冷性番茄品种提供了进一步的遗传知识。
