脂肪族芥子油苷侧链修饰酶基因FMO_(GS-OX4)表达模式分析

Expression Pattern of FMO_(GS-OX4),a Biosynthetic Gene Involved in Aliphatic Glucosinolate Side-chain Modification

芥子油苷是一类由氨基酸衍生而来的、在植物抗生物胁迫防御性反应中起重要作用的次生代谢产物,其生物活性与侧链结构密切相关。拟南芥中有5个黄素单氧化酶FMOGS-OX1-5具有催化芥子油苷侧链上硫原子氧化的活性,使甲基硫烷芥子油苷转变为甲基亚磺酰烷芥子油苷。前期研究工作表明,在5个FMOGS-OX基因缺失突变体中,除了fmogs-ox4外均表现出芥子油苷侧链结构变化的表型。为了深入揭示FMOGS-OX4的表达特性和它对芥子油苷侧链的修饰作用,利用GFP和GUS为报告基因,系统地分析了FMOGS-OX4在不同组织中的表达情况。结果表明FMOGS-OX4主要在花梗、叶片及角果的维管组织中表达,在正常生长条件下,FMOGS-OX4表达的空间位置与芥子油苷的分布不重叠,因而,酶与底物的分离可能是fmogs-ox4没有明显表型的主要原因。

Glucosinolates（GSLs）are amino acid-derived secondary metabolites,which play an important role in biotic defense reactions in plants.The bioactivity of GSLs is closely related with its chain structure.There are five Flavin-containing Monooxygenase（FMO）enzymes,FMOGS-OX1-5,involved in GSL biosynthesis catalyzing the S-oxygenation from Methylthioalkyl GSLs to Methylsulfinylalkyl GSLs.Our previous work showed that all fmogs-ox mutants,except fmogs-ox4,presented altered GSLs phenotypes.To reveal the expression characteristics and functions in GSLs biosynthesis and chain structure modification,GFP and GUS were used as reporter genes,expression pattern of FMOGS-OX4 in different tissue was analyzed and results showed that FMOGS-OX4 was expressed mainly in the vascular tissue of the leaf,stem and silique.Under normal conditions,spatial distribution of FMOGS-OX4 did not overlap with the distribution of its substrates,which was considered as the reason why fmogs-ox4 lacked altered GSLs phenotype.