State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Jahn Research Group, USDA/FPL, Madison, WI 53726, USA.
Genes (Basel). 2021 Jul 13;12(7):1064. doi: 10.3390/genes12071064.
Xishuangbanna (XIS) cucumber ( L. var. Qi et Yuan), is a botanical variety of cucumber cultivars native to southwest China that possesses excellent agronomic traits for cucumber improvement. However, breeding utilization of XIS cucumber is limited due to the current poor understanding of its photoperiod-sensitive flowering characteristics. In this study, genetic and transcriptomic analysis were conducted to reveal the molecular basis of photoperiod-regulated flowering in XIS cucumber. A major-effect QTL locus was identified that controls the days to first flowering (DFF) of XIS cucumbers with a span of 1.38 Mb. Whole-genome re-sequencing data of 9 cucumber varieties with different flowering characteristics in response to photoperiod suggested that was the candidate gene of , which harbored a single non-synonymous mutation in its fifth exon. Transcriptomic analysis revealed the positive roles of auxin and ethylene in accelerating flowering under short-day (SD) light-dark cycles when compared with equal-day/night treatment. Carbohydrate storage and high expression levels of related genes were important reasons explaining early flowering of XIS cucumber under SD conditions. By combining with the RNA-Seq data, the co-expression network suggested that integrated multiple types of genes to regulate the flowering of XIS cucumber. Our findings explain the internal regulatory mechanisms of a photoperiodic flowering pathway. These findings may guide the use of photoperiod shifts to promote flowering of photoperiod-sensitive crops.
西双版纳（XIS）黄瓜（L. var. Qi et Yuan）是一种原产于中国西南地区的黄瓜品种，具有优良的农艺性状，可用于黄瓜改良。然而，由于目前对其光周期敏感开花特性的了解有限，XIS 黄瓜的育种利用受到限制。本研究通过遗传和转录组分析，揭示了 XIS 黄瓜光周期调控开花的分子基础。鉴定到一个控制 XIS 黄瓜首次开花天数（DFF）的主效 QTL 位点，跨度为 1.38 Mb。对 9 个具有不同光周期开花特性的黄瓜品种进行全基因组重测序数据表明，是候选基因，其第五外显子存在单个非同义突变。转录组分析表明，与等长光照/黑暗处理相比，在短日照（SD）光暗循环下，生长素和乙烯加速开花的作用。碳水化合物储存和相关基因的高表达水平是 XIS 黄瓜在 SD 条件下早期开花的重要原因。通过与 RNA-Seq 数据相结合，共表达网络表明 整合了多种类型的基因来调节 XIS 黄瓜的开花。我们的研究结果解释了光周期开花途径的内部调节机制。这些发现可能指导利用光周期变化来促进光周期敏感作物的开花。
