Xue Yufei, Chen Baojun, Wang Rui, Win Aung Naing, Li Jiana, Chai Yourong
Chongqing Rapeseed Engineering Research Center; Chongqing Key Laboratory of Crop Quality Improvement; Engineering Research Center of South Upland Agriculture of Ministry of Education; College of Agronomy and Biotechnology, Southwest University, 2# Tiansheng Road, Beibei, Chongqing, 400715, People's Republic of China.
Appl Biochem Biotechnol. 2018 Feb;184(2):582-598. doi: 10.1007/s12010-017-2563-8. Epub 2017 Aug 10.
Rapeseed (Brassica napus) is an important oilseed crop worldwide, and fatty acid (FA) compositions determine the nutritional and economic value of its seed oil. Fatty acid desaturases (FADs) play a pivotal role in regulating FA compositions, but to date, no comprehensive genome-wide analysis of FAD gene family in rapeseed and its parent species has been reported. In this study, using homology searches, 84, 45, and 44 FAD genes were identified in rapeseed, Brassica rapa, and Brassica oleracea genomes, respectively. These FAD genes were unevenly located in 17 chromosomes and 2 scaffolds of rapeseed, 9 chromosomes and 1 scaffold of B. rapa, and all the chromosomes of B. oleracea. Phylogenetic analysis showed that the soluble and membrane-bound FADs in the three Brassica species were divided into four and six subfamilies, respectively. Generally, the soluble FADs contained two conserved histidine boxes, while three highly conserved histidine boxes were harbored in membrane-bound FADs. Exon-intron structure, intron phase, and motif composition and position were highly conserved in each FAD subfamily. Putative subcellular locations of FAD proteins in three Brassica species were consistent with those of corresponding known FADs. In total, 25 of simple sequence repeat (SSR) loci were found in FAD genes of the three Brassica species. Transcripts of selected FAD genes in the three species were examined in various organs/tissues or stress treatments from NCBI expressed sequence tag (EST) database. This study provides a critical molecular basis for quality improvement of rapeseed oil and facilitates our understanding of key roles of FAD genes in plant growth and development and stress response.
油菜（甘蓝型油菜）是全球重要的油料作物，脂肪酸（FA）组成决定了其种子油的营养和经济价值。脂肪酸去饱和酶（FADs）在调节FA组成中起关键作用，但迄今为止，尚未见关于油菜及其亲本物种FAD基因家族的全基因组综合分析报道。本研究通过同源搜索，分别在油菜、白菜和甘蓝基因组中鉴定出84个、45个和44个FAD基因。这些FAD基因不均匀地分布在油菜的17条染色体和2个支架、白菜的9条染色体和1个支架以及甘蓝的所有染色体上。系统发育分析表明，三个芸苔属物种中的可溶性和膜结合FAD分别分为四个和六个亚家族。一般来说，可溶性FAD包含两个保守的组氨酸框，而膜结合FAD含有三个高度保守的组氨酸框。每个FAD亚家族的外显子-内含子结构、内含子相位以及基序组成和位置高度保守。三个芸苔属物种中FAD蛋白的推定亚细胞定位与相应已知FAD的定位一致。在三个芸苔属物种的FAD基因中共发现25个简单序列重复（SSR）位点。从NCBI表达序列标签（EST）数据库中检测了三个物种中选定FAD基因在各种器官/组织或胁迫处理下的转录本。本研究为油菜籽油品质改良提供了关键的分子基础，并有助于我们理解FAD基因在植物生长发育和胁迫响应中的关键作用。
