Department of Horticulture, Graduate Program in Plant Breeding, Genetics and Biotechnology, Michigan State University, East Lansing, MI 48824, USA.
Department of Plant and Agroecosystem Sciences, University of Wisconsin, Madison, WI 53706, USA.
Int J Mol Sci. 2024 Aug 28;25(17):9306. doi: 10.3390/ijms25179306.
The fruit surface is a critical first line of defense against environmental stress. Overlaying the fruit epidermis is the cuticle, comprising a matrix of cutin monomers and waxes that provides protection and mechanical support throughout development. The epidermal layer of the cucumber ( L.) fruit also contains prominent lipid droplets, which have recently been recognized as dynamic organelles involved in lipid storage and metabolism, stress response, and the accumulation of specialized metabolites. Our objective was to genetically characterize natural variations for traits associated with the cuticle and lipid droplets in cucumber fruit. Phenotypic characterization and genome-wide association studies (GWAS) were performed using a resequenced cucumber core collection accounting for >96% of the allelic diversity present in the U.S. National Plant Germplasm System collection. The collection was grown in the field, and fruit were harvested at 16-20 days post-anthesis, an age when the cuticle thickness and the number and size of lipid droplets have stabilized. Fresh fruit tissue sections were prepared to measure cuticle thickness and lipid droplet size and number. The collection showed extensive variation for the measured traits. GWAS identified several QTLs corresponding with genes previously implicated in cuticle or lipid biosynthesis, including the transcription factor , as well as suggesting new candidate genes, including a potential lipid-transfer domain containing protein found in association with isolated lipid droplets.
果实表面是抵御环境压力的第一道重要防线。覆盖在果实表皮上的是角质层，由角质单体和蜡质组成的基质构成，在整个发育过程中提供保护和机械支撑。黄瓜（L.）果实的表皮层还含有明显的脂滴，这些脂滴最近被认为是参与脂质储存和代谢、应激反应以及特殊代谢物积累的动态细胞器。我们的目标是从遗传上表征与黄瓜果实的角质层和脂滴相关的性状的自然变异。使用一个重测序的黄瓜核心收集品系进行了表型特征分析和全基因组关联研究（GWAS），该收集品系涵盖了美国国家植物种质系统收集品系中存在的超过 96%的等位基因多样性。该收集品系在田间种植，果实于花后 16-20 天收获，此时角质层厚度和脂滴的数量和大小已经稳定。准备新鲜的果实组织切片来测量角质层厚度和脂滴的大小和数量。该收集品系显示出所测性状的广泛变异。GWAS 鉴定出了几个与先前涉及角质层或脂质生物合成的基因相对应的 QTL，包括转录因子 ，以及提出了新的候选基因，包括与分离的脂滴相关的潜在脂质转移结构域蛋白。
