三倍体无籽西瓜果实发育期番茄红素合成代谢酶基因的表达

Expression of lycopene synthesis and metabolism genes during maturation of triploid seedless watermelon

【目的】探讨红瓤、黄瓤无籽西瓜果实在不同发育时期番茄红素的积累差异、合成关键酶基因PSY、PDS、ZDS、CRTISO、LCYb的表达差异。【方法】选择无籽西瓜品种‘蜜枚’(红瓤)、‘黄枚’(黄瓤)为试材,采用分光光度计法和实时荧光定量PCR技术分别对果实发育过程中番茄红素的积累以及合成途径关键酶基因的表达进行分析。【结果】(1)‘蜜枚’番茄红素含量随着果实的发育逐渐升高,在授粉后35 d时达到最高;而‘黄枚’番茄红素积累量很少,在发育过程中一直处于较低水平。(2)2种瓤色无籽西瓜PSY基因的最高表达量都出现在授粉后25 d,从25 d开始PSY的表达量一直远高于其他基因,红瓤无籽西瓜LCYb基因的表达量一直处于最低水平,而黄瓤无籽西瓜LCYb基因的表达量仅低于PSY,高于其他3个基因的表达量。【结论】授粉后25 d可能是番茄红素积累的关键时期,番茄红素合成途径上游的PSY基因和控制分解的LCYb基因在番茄红素合成中可能起着较为重要的作用,而LCYb基因对瓤色起着重要的作用。

【Objective】 To analyze the accumulation difference of lycopene and the gene expression difference of PSY,PDS,ZDS,CRTISO,LCYb during fruit development and ripening in seedless watermelon including red and yellow flesh. 【Method】 Triploid seedless watermelon including ‘Mimei'(red flesh) and‘Huangmei'(yellow flesh) were used for the study of the lycopene content and the five key enzyme genes expression of lycopene synthesis in different development stages of fruits. 【Result】(1) the content of lycopene of ‘Mimei' gradually increased in fruit ripening process and was the highest at 35 d after pollination; while the lycopene accumulation of ‘Huangmei' was little during fruit ripening process.(2) The higher expression level of PSY gene in two varieties was 25 d after pollination, and the expression level of PSY gene was higher than other genes from 25 d after pollination to ripening. The LCYb gene expression level of red flesh seedless watermelon has been at lower level during fruit development and ripening, while the expression of LCYb gene in yellow flesh seedless watermelon was only lower than that of PSY gene, while higher than other genes. 【Conclusion】 The 25 day after pollination may be the key period of lycopene accumulation, the PSY gene regulating lycopene synthesis and the LCYb gene determining decomposition may be play an important role,and LCYb gene plays an important role in the determination of the flesh color.