Genome-wide identification, spatio-temporal expression analysis and functional characterization of selected Brassica napus GPATs highlight their roles in cuticular wax biosynthesis and defense against fungal pathogens. Glycerol-3-phosphate 1-O-acyltransferase (GPAT) is a key enzyme in the biosynthesis of glycerolipids, a major component of cellular membranes and extracellular protective layers, such as cuticles in plants. Brassica napus is an economically important crop and cultivated worldwide mostly for its edible oil. The B. napus GPATs (BnGPATs) are insufficiently characterized. Here, we performed genome-wide analysis to identify putative GPATs in B. napus and its diploid progenitors B. rapa and B oleracea. The 32 B. napus BnGPATs are phylogenetically divided into three major groups, cutin, suberin, and diverse ancient groups. Analysis of transcriptomes of different tissues and seeds at different developmental stages revealed the spatial and temporal expression profiles of BnGPATs. The yield and oil quality of B. napus are adversely affected by the necrotrophic fungus, Sclerotinia sclerotiorum. We showed that several BnGPATs, including cutin-related BnGPAT19 and 21, were upregulated in the S. sclerotiorum resistant line. RNAi-mediated suppression of BnGPAT19 and 21 in B. napus resulted in thinner cuticle, leading to rapid water and chlorophyll loss in toluidine blue staining and leaf bleaching assays. In addition, the RNAi plants also developed severe necrotic lesions following fungal inoculation compared to the wild-type plants, indicating that BnGPAT19 and 21 are likely involved in cuticular wax biosynthesis that is critical for initial pathogen defense. Taken together, we provided a comprehensive account of GPATs B. napus and characterized BnGPAT19 and 21 for their potential roles in cuticular wax biosynthesis and defense against fungal pathogens.

中文翻译：

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甘蓝型油菜中 3-磷酸甘油 O-酰基转移酶基因家族的全基因组分析和两个角质组 GPAT 的功能表征

选定的欧洲油菜 GPAT 的全基因组鉴定、时空表达分析和功能表征突出了它们在表皮蜡生物合成和防御真菌病原体中的作用。甘油-3-磷酸 1-O-酰基转移酶 (GPAT) 是甘油脂生物合成的关键酶，甘油脂是细胞膜和细胞外保护层（如植物角质层）的主要成分。油菜是一种重要的经济作物，在世界范围内种植主要是为了食用油。油菜 GPAT (BnGPAT) 的特征不足。在这里，我们进行了全基因组分析，以鉴定欧洲油菜及其二倍体祖先油菜和甘蓝中假定的 GPAT。32 个欧洲油菜 BnGPAT 在系统发育上分为三大类：角质、木栓质和不同的古代组。不同组织和种子在不同发育阶段的转录组分析揭示了 BnGPATs 的时空表达谱。B. napus 的产量和油质受到坏死性真菌核盘菌（Sclerotinia sclerotiorum）的不利影响。我们发现几种 BnGPAT，包括与角质相关的 BnGPAT19 和 21，在核盘菌抗性系中上调。RNAi 介导的对欧洲油菜中 BnGPAT19 和 21 的抑制导致表皮变薄，从而导致甲苯胺蓝染色和叶片漂白测定中水分和叶绿素的快速损失。此外，与野生型植物相比，RNAi 植物在真菌接种后也出现了严重的坏死病变，这表明 BnGPAT19 和 21 可能参与了对初始病原体防御至关重要的角质层蜡生物合成。