State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, College of Horticulture, Nanjing Agricultural University, Weigang Campus, Nanjing, 210095, China.
Plant Sci. 2024 Nov;348:112237. doi: 10.1016/j.plantsci.2024.112237. Epub 2024 Aug 23.
Cold stress detrimentally influences fruit development, leading to a substantial yield reduction in many fruit-bearing vegetables. Cucumber, a vegetable of subtropical origin, is especially sensitive to cold. Cold-inducible parthenocarpy (CIP) promises fruit yield under cold conditions. Previously, we identified a CIP line EC5 in cucumber, which showed strong parthenocarpy and sustained fruit growth under cold conditions (16°C day/10°C night). However, the candidate gene and genetic mechanism underlying CIP in cucumber remain unknown. In this study, both BSA-seq and conventional QTL mapping strategies were employed on F populations to delve into the genetic control of CIP. A single QTL, CIP5.1, was consistently mapped across two winter seasons in 2021 and 2022. Fine mapping delimited the CIP locus into a 38.3 kb region on chromosome 5, harboring 8 candidate genes. Among these candidates, CsAGL11 (CsaV3_5G040370) was identified, exhibiting multiple deletions/insertions in the promoter and 5'UTR region. The CsAGL11 gene encodes a MADS-box transcription factor protein, which is homologous to the genes previously recognized as negative regulators in ovule and fruit development of Arabidopsis and tomato. Correspondingly, cold treatment resulted in decreased expression of CsAGL11 during the early developmental stage of the fruit in EC5. A promoter activity assay confirmed promoter polymorphisms leading to weak transcriptional activation of CsAGL11 under cold conditions. This study deepens our understanding of the genetic characteristics of CIP and elucidates the potential role of the CsAGL11 gene in developing cucumber cultivars with enhanced fruiting under cold conditions.
冷胁迫会对果实发育产生不利影响，导致许多结果蔬菜的产量大幅下降。黄瓜起源于亚热带，对低温特别敏感。冷诱导单性结实（CIP）有望在低温条件下实现果实产量。此前，我们在黄瓜中鉴定出一个 CIP 系 EC5，该系在低温条件下（16°C 白天/10°C 夜间）表现出强烈的单性结实和持续的果实生长。然而，黄瓜中 CIP 的候选基因和遗传机制仍不清楚。在这项研究中，我们在 F 群体上同时使用 BSA-seq 和常规 QTL 作图策略，深入研究 CIP 的遗传控制。一个单一的 QTL，CIP5.1，在 2021 年和 2022 年的两个冬季季节中始终被定位。精细定位将 CIP 基因座限定在 5 号染色体上的 38.3kb 区域内，包含 8 个候选基因。在这些候选基因中，CsAGL11（CsaV3_5G040370）被鉴定出来，其启动子和 5'UTR 区域存在多个缺失/插入。CsAGL11 基因编码一个 MADS 框转录因子蛋白，与先前在拟南芥和番茄中鉴定为胚珠和果实发育的负调控因子的基因同源。相应地，在 EC5 中，低温处理导致果实早期发育阶段 CsAGL11 的表达减少。启动子活性测定证实，启动子多态性导致 CsAGL11 在低温条件下的转录激活较弱。本研究加深了我们对 CIP 遗传特征的理解，并阐明了 CsAGL11 基因在培育低温下果实结实增强的黄瓜品种中的潜在作用。
