Expression patterns of the genes(KCS,KCR,HCD and ECR gene)involved in biosynthesis and accumulation of nervonic acid were studied and compared in high and low nervonic acid-yielding Xanthoceras sorbifolium Bunge during embry-onic development using semi-quantitative RT-PCR technology. This will play an important role for understanding molecular mechaisms of biosynthesis and accumulation of nervonic acid in X. sorbifolium. The results showed that the expression levels of four genes were highest in embryos of two lines at the 40 days after anthesis compared to that of other developmental stages,and then the expression levels decreased or was very low during the subsequent embryo development. The expression level of KCS gene was higher in HNA line than LNA line at 40 d,but its expression level was lower in HNA line compared to LNA line at 54,68 and 81 d. In contrast to the KCS gene,the expression level of HCD gene was lower in HNA line than LNA line at 40 daa,whereas its expression level was higher in HNA line compared to LNA line at 54,68 and 81 d. The ex-pression level of KCR gene was relatively low in HNA compared with LNA. The expression level of ECR gene in HNA was higher compared with LNA at 40 and 81 d. These results indicated that the 40 d was a critical stage for the accumulation of nervonic acid in embryonic development. KCS and ECR genes mainly regulate the biosynthesis of nervonic acid in the early stage of embryonic development(at 40 d). The HCD gene regulates the biosynthesis of nervonic acid in the medium and late stages of embryonic development.%利用半定量RT-PCR技术分析比较文冠果(Xanthoceras sorbifolium Bunge)种子发育过程中神经酸合成相关基因(KCS、KCR、HCD和ECR基因)在文冠果高神经酸(HNA)、低神经酸(LNA)品系的表达模式,旨在为解析文冠果神经酸合成与积累的分子机制提供重要参考.结果表明,4个基因在两个品系花后40 d的种胚中表达量最高,在随后的种胚发育过程中表达量呈下降趋势或表达量极低.在花后40 d时KCS基因在HNA品系中的表达量高于LNA,但花后54、68和81 d时在HNA品系中的表达量低于LNA.与KCS基因不同的是,HCD基因在HNA品系花后40 d种胚中的表达量低于LNA,而在花后54、68和81 d时HNA品系中的表达量高于LNA.KCR基因在HNA品系种胚中的表达量均低于LNA.ECR基因在HNA品系花后40和82 d种胚中的表达量高于LNA,表明花后40 d是种胚发育过程中神经酸积累的关键时期.KCS和ECR基因主要在种胚发育的早期(花后40 d)调控神经酸的合成,HCD基因在种胚发育的中期和后期调节神经酸的合成过程.
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