金荞麦查尔酮异构酶的基因克隆及其花期表达与黄酮量分析

目的 获取金荞麦总黄酮合成途径的关键酶查尔酮异构酶（chalcone isomerase，CHI）基因的全长序列，并进行序列分析；对花期金荞麦CHI基因在各组织中的表达与总黄酮量进行分析。方法 利用同源克隆技术获得金荞麦查尔酮异构酶基因（FdCHI）的cDNA序列；采用半定量RT-PCR对CHI表达量进行分析，并采用AlCl₃法测量总黄酮量。结果 金荞麦FdCHI基因cDNA包含一个750 bp的ORF，编码249个氨基酸，命名为FdCHI。生物信息学分析表明该编码蛋白与其他植物CHI氨基酸序列同源率较高。FdCHI在花期金荞麦不同组织中的表达量分析表明，其表达量花＞根＞叶＞茎，总黄酮量为花＞叶＞茎＞根。结论 在金荞麦中首次获得CHI基因的cDNA序列，编码蛋白具有CHI同源蛋白的典型特征。FdCHI基因在金荞麦茎、叶和花中的表达量与总黄酮量具有相关性，但在根中表达量与总黄酮量相关性较小。

Gene cloning and expression level of chalcone isomerase during florescence and content of flavonoids in Fagopyrum dibotrys

Objective To clone and analyze the full-length cDNA of chalcone isomerase (CHI) gene from Fagopyrum dibotrys (FdCHI). To analyze the expression of CHI and the total flavonoids content during florescence of F. dibotrys. Methods The cDNA sequence of CHI was cloned by homology cloning from F. dibotrys. The expression of CHI was analyzed in the different tissues during florescence by semi-quantitative RT-PCR. The content of total flavonoids was measured by AlCl₃ method. Results The open reading frame (ORF) of FdCHI was 750 bp and encoded a protein with 249 amino acids. Bioinforamtion analysis suggested that the amino acid sequence of FdCHI had the high homology with those in other plants. Gene expression analysis showed that FdCHI was highly expressed in the flowers, followed by the roots and leaves, while lower in the stems. The content of total flavonoids was the highest in the flowers then the leaves and stems, and the lowest was in the roots. Conclusion The cDNA sequence of FdCHI is firstly obtained from F. dibotrys and its coding protein has the typical characteristic of CHI homologous protein. The gene expression of FdCHI shows the same to the total flavonoids content in the stems, leaves, and flowers, but different in the roots of F. dibotrys.