National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan, 430070, China.
College of Life Sciences, Gannan Normal University, Ganzhou, 341000, China.
Plant J. 2024 Sep;119(5):2385-2401. doi: 10.1111/tpj.16925. Epub 2024 Jul 10.
ERFs (ethylene-responsive factors) are known to play a key role in orchestrating cold stress signal transduction. However, the regulatory mechanisms and target genes of most ERFs are far from being well deciphered. In this study, we identified a cold-induced ERF, designated as PtrERF110, from trifoliate orange (Poncirus trifoliata L. Raf., also known as Citrus trifoliata L.), an elite cold-hardy plant. PtrERF110 is a nuclear protein with transcriptional activation activity. Overexpression of PtrERF110 remarkably enhanced cold tolerance in lemon (Citrus limon) and tobacco (Nicotiana tabacum), whereas VIGS (virus-induced gene silencing)-mediated knockdown of PtrERF110 drastically impaired the cold tolerance. RNA sequence analysis revealed that PtrERF110 overexpression resulted in global transcriptional reprogramming of a range of stress-responsive genes. Three of the genes, including PtrERD6L16 (early responsive dehydration 6-like transporters), PtrSPS4 (sucrose phosphate synthase 4), and PtrUGT80B1 (UDP-glucose: sterol glycosyltransferases 80B1), were confirmed as direct targets of PtrERF110. Consistently, PtrERF110-overexpressing plants exhibited higher levels of sugars and sterols compared to their wild type counterparts, whereas the VIGS plants had an opposite trend. Exogenous supply of sucrose restored the cold tolerance of PtrERF110-silencing plants. In addition, knockdown of PtrSPS4, PtrERD6L16, and PtrUGT80B1 substantially impaired the cold tolerance of P. trifoliata. Taken together, our findings indicate that PtrERF110 positively modulates cold tolerance by directly regulating sugar and sterol synthesis through transcriptionally activating PtrERD6L16, PtrSPS4, and PtrUGT80B1. The regulatory modules (ERF110-ERD6L16/SPS4/UGT80B1) unraveled in this study advance our understanding of the molecular mechanisms underlying sugar and sterol accumulation in plants subjected to cold stress.
乙烯响应因子（ethylene-responsive factors，ERFs）在协调冷胁迫信号转导中起着关键作用。然而，大多数 ERFs 的调控机制和靶基因远未被很好地阐明。在这项研究中，我们从三叶橙（Poncirus trifoliata L. Raf.，也称为 Citrus trifoliata L.）中鉴定出一个冷诱导的 ERF，命名为 PtrERF110，三叶橙是一种耐寒的优良植物。PtrERF110 是一种具有转录激活活性的核蛋白。过表达 PtrERF110 可显著增强柠檬（Citrus limon）和烟草（Nicotiana tabacum）的耐寒性，而 VIGS（病毒诱导基因沉默）介导的 PtrERF110 敲低则严重损害了耐寒性。RNA 序列分析表明，PtrERF110 的过表达导致一系列应激响应基因的全基因组转录重编程。其中 3 个基因，包括 PtrERD6L16（早期响应脱水 6 样转运蛋白）、PtrSPS4（蔗糖磷酸合酶 4）和 PtrUGT80B1（UDP-葡萄糖：甾醇糖基转移酶 80B1），被确认为 PtrERF110 的直接靶标。一致地，与野生型相比，PtrERF110 过表达的植物表现出更高水平的糖和甾醇，而 VIGS 植物则呈现相反的趋势。蔗糖的外源供应恢复了 PtrERF110 沉默植物的耐寒性。此外，敲低 PtrSPS4、PtrERD6L16 和 PtrUGT80B1 会严重损害三叶橙的耐寒性。总之，我们的研究结果表明，PtrERF110 通过直接转录激活 PtrERD6L16、PtrSPS4 和 PtrUGT80B1 来调节糖和甾醇的合成，从而正向调节耐寒性。本研究中揭示的调控模块（ERF110-ERD6L16/SPS4/UGT80B1）加深了我们对植物在冷胁迫下糖和甾醇积累的分子机制的理解。
