甘蓝型油菜油酸脱氢酶基因(fad2)多个拷贝的发现及分析  

Screening and Analysis of Mutiple Copy of Oleate Desaturase Gene(fad2) in Brassica napus

作　　者：肖钢[1,2] 张宏军 彭琪[1] 官春云[1,2] 

机构地区：[1]湖南农业大学作物基因工程湖南省重点实验室,湖南长沙410128 [2]湖南农业大学油料作物研究所／国家油料作物改良中心湖南分中心,湖南长沙410128

出　　处：《作物学报》2008年第9期1563-1568,共6页Acta Agronomica Sinica

基　　金：国家重点基础研究发展计划(973计划):油菜籽油脂形成的分子生物学机制及其代谢调控(2006CB101600)

摘　　要：以甘蓝型油菜湘油15为材料,随机挑选56个来自基因组的fad2基因克隆、47个来自幼苗整株的fad2基因cDNA克隆和9个授粉27d后种子中fad2 cDNA克隆进行双向测序。基因组中56个fad2序列的碱基同源性为91.0%～99.9%,从中得到11个差异序列,即11个不同的fad2基因拷贝。将其翻译成氨基酸序列发现,6个拷贝在编码区中出现多个终止密码子,另外5个的同源性为90.60%～99.74%,与47个来自幼苗整株的fad2基因cDNA序列进行比较,发现fad2基因没有内含子。从种子中的9个fad2 cDNA克隆序列中找到2个有差异的cDNA,它们的编码区中没有终止密码子,说明在种子中有多个fad2基因表达。基因组中的11个拷贝根据同源性可分成两组,命名为fad2I和fad2II。RT-PCR分析发现在授粉27d的种子中fad2I有较强表达,fad2II没有表达;但在叶片中两者都有表达。Rapeseed oil is primarily composed of palmitic, stearic, oleic, linoleic and linolenic fatty acids. Delta-12 desaturase （FAD2） in plants converts oleic acid （18：1） to linoleic acid （18：2） by inserting a double bond at the delta-12 position. Fatty acid desaturase-2 gene （fad2） encodes delta-12 desaturase that functions in the endoplasmic reticulum. Fifty-six fad2 DNA clones and nine fad2 seed cDNA clones of B. napus cv. Xiangyou 15 were randomly selected and sequenced in this study. These 56 DNA sequences share 91.0-99.9% identity in nucleotides. Through combination of identical sequences, ll different sequences were found, of which each represented various copy of fad2 gene. Deduced amino acid sequences revealed that many stop codons occurred in the coding region of six copies, the other five copies shared 90.60-99.74% amino-acid identity. Two differential cDNA were found from nine fad2 seed cDNA sequence, no stop codons in the coding region, revealing that more than one fad2 gene express in developing seeds, and oleic acid content is controlled by multigene. The eleven copies in genome could be divided into two groups based on their homology, and designated as fad2I and fad2II, respectively. RT-PCR analysis in seeds at twenty-seven days after pollination showed thatfad2I expressed strongly in seeds, and no expression offad2II was found, but both of them ex- pressed in leaves.

关 键 词：甘蓝型油菜 油酸脱氢酶基因 基因拷贝数 序列差异引物 

分 类 号：S565.4[农业科学—作物学] Q786[生物学—分子生物学]