GENE-EXPRESSION OF GIBBERELLIN BIOSYNTHETIC ENZYMES DURING SOMATIC EMBRYOGENESIS IN CARROT PLANT

为了阐明赤霉酸(GA)在胡萝卜体细胞胚胎发生中的作用，我们重点研究了GA生物合成酶和失活酶的一些基因。我们从体细胞胚胎中克隆了编码GA20-氧化酶、GA3-β-羟基酶和GA2-氧化酶的基因。在大肠杆菌中表达了这些基因的全长，并对这些翻译产物的功能进行了分析。已证实这些基因编码GA生物合成酶或失活酶。我们还利用半定量PCR方法显示了这些基因在体细胞胚胎发生过程中的表达模式。其中，编码GA_3β-羟基酶的3个基因的表达呈现体细胞胚胎特异性模式。虽然我们尝试了其中一个GA3β羟基酶基因的原位杂交，但在体细胞胚胎的任何阶段都没有观察到明显的信号。

To clarify role of gibberellic acid (GA) for somatic embryogenesis in carrot plant, we focused few genes for GA biojsynthetic and inactivating enzymes. We cloned putative genes encoding GA 20-oxidase, GA 3 β-hydroxylase, and GA 2-oxidase from the somatic embryos. Full-length these genes were expressed in E. coli, and functions of these translational products were analyzed. It was demonstrated that these genes encode GA biosynthetic or inactivating enzymes. We also showed expression pattern of these genes during somatic embryogenesis by using semi-quantitative PCR method. Especially, expression of three genes encoding GA 3β-hydroxylase shows somatic embryo specific pattern. Although we tried in situ hybridization for one of these genes for GA 3 β-hydroxylase, no significant signals were observed in any stage of somatic embryo.