非洲紫罗兰两侧与辐射对称花中两个CYC类完整基因的分离和序列分析

在已知GCYC基因部分序列基础上, 通过改进的mTAIL-PCR方法克隆非洲紫罗兰Saintpaulia ionantha两侧对称栽培种中CYC类基因的5′未知序列, 并进而从两侧与辐射对称栽培种中分离得到苦苣苔科Gesneriaceae中第一组完整基因: SiCYC1A与SiCYC1B。对以上基因的核酸和氨基酸序列比较发现, SiCYC1A与SiCYC1B序列同源性很高, 均含有完整的功能调控区域(即TCP domain和R domain)并与模式植物金鱼草Antirrhinum majus中CYC基因同源。因此, 这两个基因应具有正常功能, 是功能上互补的冗余基因。令人意外的是在辐射对称花栽培品种中的这两个基因和两侧对称花栽培品种中对应基因的序列完全相同。经过对金鱼草以及相关类群辐射对称花突变体中CYC类基因序列的比较分析, 推论在非洲紫罗兰中, SiCYC1A与SiCYC1B基因可能受上游未知的共同调控因子调控, 该调控因子的改变是导致栽培品种中花对称性发生变化的主要原因。另外, 对改进后的TAIL-PCR(mTAIL-PCR)的方法和过程进行了详细叙述, 并对其技术特征和优势开展了简单的论述。

Isolation and sequence analysis of two CYC-like genes, SiCYC1A and SiCYC1B, from zygomorphic and actinomorphic cultivars of Saintpaulia ionantha (Gesneriaceae)

Using the mTAIL-PCR method, we have isolated the two CYC-like genes, SiCYCIA and SiCYCIB, from zygomorphic and actinomorphic cultivars of Saintpaulia ionantha respectively in Gesneriaceae. The two genes, SiCYCIA and SiCYCIB, from the zygomorphic cultivar both contain the whole regulation domain, i.e. TCP and R domains. Therefore, they should be functional in the floral symmetry establishment, homologous with CYC in Antirrhinum majus. Unexpectedly, the two genes from the actinomorphic cultivar are identical to those from the zygomorphic in DNA sequence, respectively. Based on comparative analysis of the molecular alteration at CYC-like genes, which are responsible for the morphological transformation from zygomorphy to actinomorphy, we suggest that the two closely related genes SiCYC1A and SiCYCIB might be regulated by a common upstream regulator, whose change would result in silence of both SiCYC1A and SiCYC1B in controlling the development of the adaxial and lateral organs in a flower. In addition, an mTAIL-PCR method was shown to have the technological advantages of the unknown sequence for isolation.