夏橙果实发育后期及返青期类胡萝卜素积累及乙烯的调控

Carotenoid Accumulation and Its Regulation by Ethylene in Fruits of Valencia Orange During Its Late Development and Re-Greening Stages

【目的】明确夏橙发育后期转黄及返青过程中类胡萝卜素积累及关键合成酶基因表达的变化及乙烯的调控作用。【方法】将夏橙果实发育的后期和成熟过程分为转黄期(P1—P4)及返青期(P5—P7)共7个时期,通过比色法和Northern-blotting法分析发育后期成熟过程中及乙烯作用下果皮中类胡萝卜素的含量及其合成关键酶PSY、PDS和ZDS基因表达水平的变化。【结果】证实P1—P7发育过程中果皮发生由青至黄,继而返青的颜色变化,与果皮中类胡萝卜素积累及其合成途径中PSY、PDS和ZDS基因表达水平的变化趋势一致。乙烯可促进转黄期夏橙果皮中类胡萝卜素积累及PSY基因的表达,而对PDS和ZDS基因表达的影响不显著。乙烯处理不影响返青期果实中类胡萝卜素的积累,但能够阻碍果实成熟后期PSY和PDS基因表达水平的减弱。【结论】夏橙果实在发育后期及成熟过程中,乙烯在转黄期及返青期对类胡萝卜素积累及PSY和PDS基因表达的影响不同,暗示乙烯的调控作用还受果实发育相关因子的影响。在夏橙转黄期可以用乙烯促进转黄着色,而在返青期利用乙烯不能达到脱绿的效果。

【Objective】In order to explore the changes of carotenoid content,the transcription level of genes encoding a few key enzymes in carotenoid biosynthetic pathway,and the regulation effect of ethylene in carotenoid biosynthesis in fruits of Valencia orange during the late yellowing and re-greening stages.【Method】Fruit late development and maturation process of Valencia orange were divided into four yellowing periods（P1-P4） and three re-greening periods（P5-P7）,the carotenoid content and the gene expression of PSY,PDS and ZDS were analyzed accordingly.【Result】Results demonstrated that peel color during the developmental process from P1 to P7 firstly turns from green to yellow,then to green again,which was consistent with the changes of carotenoid accumulation and PSY,PDS and ZDS gene expression during this process.Ethylene could promote carotenoid accumulation,PSY gene expression in the peel at yellowing stage,but had no significant effects on PDS and ZDS gene expression.However,at the re-greening stage,ethylene treatment had no effects on carotenoid accumulation in the peel,but retarded the decline of PSY and PDS gene expression.【Conclusion】Results showed that in the late yellowing and re-greening stages,the regulating effects of ethylene on carotenoid accumulation and PSY,PDS gene expression were varied with fruit development stages of Valencia orange,indicating that the effects of ethylene may relate to other developmental factors.Ethylene could promote peel yellowing at the yellowing stages of Valencia orange,but re-greening was impossible by using ethylene at the re-greening stages.