胡萝卜类胡萝卜素裂解双加氧酶7基因表达与β-胡萝卜素含量相关性分析

类胡萝卜素裂解双加氧酶7(CCD7)是独角金内酯合成途径中的关键酶。为了研究胡萝卜类胡萝卜素裂解双加氧酶7基因(DcCCD7)表达与β-胡萝卜素含量的相关性,从胡萝卜(Daucus carota L.)栽培品种红福七寸和天紫中克隆获得DcCCD7。序列分析结果显示,两品种DcCCD7均包含一个1 869 bp的开放阅读框,编码622个氨基酸。序列多重比对与进化分析结果显示,DcCCD7与来自其他物种CCD7的同源性较高,其中与菊花CCD7的进化关系最近。DcCCD7为亲水性蛋白,预测的红福七寸和天紫DcCCD7蛋白三级结构均由9个α-螺旋和30个延伸主链构成。利用超高效液相色谱法(UPLC)对3个不同生长发育阶段(45、75和100 d)胡萝卜的根、叶柄和叶片中的β-胡萝卜素含量进行测定,结果显示,红福七寸主要在根和叶片中积累β-胡萝卜素,天紫主要在叶片中积累β-胡萝卜素。实时荧光定量PCR(RT-qPCR)结果显示,胡萝卜叶片中DcCCD7的表达水平显著高于根和叶柄。结果表明DcCCD7的表达量和β-胡萝卜素含量的相关性可能具有组织和品种特异性。本研究为明确DcCCD7在胡萝卜类胡萝卜素降解过程中的作用提供了一定的理论基础。

Correlation Analysis Between Carotenoid Cleavage Dioxygenase 7 Gene Expression and Content of β-carotene in Carrot

Carotenoid cleavage dioxygenase 7 (CCD7) is a key enzyme in the pathway of strigolactone synthesis. To study the correlation between DcCCD7 expression and content of β-carotene in carrot, the DcCCD7 genes were cloned from Daucus carota cultivars, Hongfuqicun and Tianzi. Sequence analysis showed that DcCCD7 from two cultivars contained an open reading frame of 1869 bp, encoding 622 amino acids. Sequence multiple alignments and evolutionary analysis showed that DcCCD7 had high homology with CCD7 from other species, among which the evolutionary relationship with chrysanthemum CCD7 was the closest. The physicochemical property analysis showed that DcCCD7 was a hydrophilic protein. Predicted tertiary structures of DcCCD7 from Hongfuqicun and Tianzi were composed of 9 α-helix and 30 extended strands. The contents of β-carotene in taproots, petioles and leaf blades of carrot at three different growth stages (45, 75 and 100 d) were determined by ultra performance liquid chromatography (UPLC). β-carotene of Hongfuqi was accumulated mainly in roots and leaves and that of Tianzi was accumulated mainly in leaves. The results of quantitative real-time PCR(RT-qPCR) showed that the expression levels of DcCCD7 in leaf blades were significantly higher than that in roots and leaf petioles. The results indicated that the correlation between the expression level of DcCCD7 and the content of β-carotene exhibited tissue and variety specificity, and other factors also affected the content of β-carotene. This study provides a theoretical basis for clarifying the role of DcCCD7 in the degradation of carotenoids.