油菜LEAFY COTYLEDON 2(BnLEC2)基因的克隆及表达分析

Cloning and Expression Analysis of LEAFY COTYLEDON 2(BnLEC2) in Brassica napus

LEAFY COTYLEDON 2(LEC2)为具有B3结构域的DNA结合蛋白家族的成员,是调控胚胎形成、种子储藏蛋白代谢和脂肪酸代谢的重要转录因子。本文对四倍体甘蓝型油菜BnLEC2基因进行了克隆,并分析了白菜Br LEC2、甘蓝Bo LEC2和甘蓝型油菜BnLEC2同源基因的进化及其表达模式。结果表明,油菜、白菜和甘蓝LEC2同源基因在进化上较为保守;但部分白菜和甘蓝LEC2同源基因的表达发生沉默。BnLEC2同源基因表达模式与其对应的白菜和甘蓝LEC2发生明显改变,前者主要在种子发育的中期高水平表达,这与油菜种子油脂等储藏物质的积累期重叠。表明BnLEC2同源基因通过改变其表达模式影响油菜种子储存物质的积累。这些结果初步揭示了多拷贝BnLEC2对油菜种子储存物质调控的协同表达模式。

LEAFY COTYLEDON 2,encoding a B3 domain binding protein,is an important transcription factor for regulating embryogenesis,seed storage protein and fatty acid metabolism. As allotetraploid oilseed plant,Brassica napus（AACC,2n = 38） originated the natural hybridization between Brassica rapa（AA,2n = 20） and Brassica oleracea（CC,2n = 18） containing duplicate genes. Here,we isolated and characterized four BnLEC2 s,which are the homologous genes to the Arabidopsis At LEC2. Results showed that these BnLEC2 s were highly conserved compared with its orthologos of Br LEC2 and Bo LEC2,and only limited divergences occurred in BnLEC2,Br LEC2 and Bo LEC2.Moreover,we found the divergences among BnLEC2 s were derived from its progenitor gene of Brassica rapa or Brassica oleracea. Furthermore,transcription analysis indicated that partial BnLEC2 homologs were silence,and the expression patterns of activated BnLEC2 were altered in contrast to its Bo LEC2 orthologs in Brassica oleracea and Br LEC2 orthologs in Brassica rapa,and which mainly expressed during the synthesis of oil and storage protein in seeds of B. napus. Taken all these together,we speculated that duplicate BnLEC2 controlled the metabolisms of oil and protein in Brassica napus seeds via the alternation of gene activation and the temporal and spatial expression pattern of BnLEC2 homologs. Our results uncovered the expression pattern of duplicate BnLEC2 regulating the synthesis of oil and storage protein in seeds of Brassica. napus.