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不同外源物质对西瓜番茄红素含量及其关键酶基因表达的影响
马荣雪, 周永海, 程登虎,等
西北农林科技大学 园艺学院
摘要:
【目的】探讨脱落酸(ABA)、MnSO4、褪黑素(MT)对西瓜番茄红素含量及其合成代谢相关酶基因表达的影响,为明确番茄红素积累内在机理和提高西瓜番茄红素含量提供理论依据。【方法】以西瓜品种玲珑王为材料,在植株伸蔓期叶面喷施ABA、MnSO4和MT,以喷施清水为对照,研究3种外源物质处理对西瓜果实发育过程中番茄红素积累及关键酶基因西瓜牻牛儿基牻牛儿基焦磷酸合成酶基因(GGPS)、植物烯合酶基因(PSY)、酶解 胡萝卜素去饱和酶基因(ZDS)、番茄红素环化酶基因(LCYB、LCYE)、9-顺式-环氧类胡萝卜素双加氧酶基因(NCED)表达模式的影响。【结果】MnSO4、ABA、MT处理均可使西瓜果实的转色期提前,并增加了果实番茄红素含量。在授粉后10 d,只有ABA、MnSO4处理可检测到西瓜果实中含有番茄红素;授粉后17 d各处理均可检测到番茄红素,授粉后17~24 d番茄红素积累速度最快;授粉后38 d时西瓜果实番茄红素含量最高,MnSO4、ABA、MT处理番茄红素含量分别为90.78,82.24和82.13 μg/g,且均显著高于清水对照(65.00 μg/g)。外源物质对西瓜果实番茄红素含量的影响受番茄红素合成代谢酶基因表达差异的调控,其中ABA处理会引起番茄红素代谢酶基因LCYB1、LCYB2、LCYE在多个时期下调表达,MnSO4处理会引起西瓜GGPS1、GGPS2、PSY1、PSY2、ZDS番茄红素合成基因在多数时期上调表达,MT处理主要引起NCED1、NCED7基因大幅下调表达。【结论】叶面喷施MnSO4、ABA、MT会加快西瓜果实番茄红素的积累,其中ABA处理主要通过降低番茄红素转化速率来实现西瓜番茄红素的积累,MnSO4处理主要通过提高番茄红素合成速率使番茄红素含量增加,MT处理主要通过NCED基因的低表达降低类胡萝卜素的分解速率,从而使番茄红素含量增加。
关键词:  西瓜  番茄红素  外源物质  代谢酶基因
DOI:
分类号:
基金项目:陕西省农业领域重点项目(2017ZDXM-NY-025);陕西省农业专项资金项目(NYKJ-2018-YL20);陕西省西甜瓜产业技术体系项目(NYKJ-2019-YL46)
Effect of different exogenous substances on watermelon lycopene content and gene expression of key enzymes
MA Rongxue, ZHOU Yonghai, CHENG Denghu,et al
Abstract:
【Objective】This study investigated the effects of abscisic acid (ABA),MnSO4 and melatonin (MT) on lycopene accumulation as well as expression of key biosynthetic genes in watermelon to provide basis for understanding lycopene accumulation and increasing lycopene content.【Method】Three exogenous substances of ABA,MnSO4 and MT were sprayed on leaves of watermelon variety of ‘Linglongwang’ during the vine elongation period using water spray as control.Then,effects of exogenous substances on lycopene accumulation during watermelon fruit development and expression patterns of key enzyme genes including geranylgeranyl pyrophosphate synthase gene (GGPS),phytoene synthase gene (PSY),zeta-carotene desaturase gene (ZDS),lycopene beta-cyclase gene (LCYB),lycopene epsilon-cyclase gene (LCYE) and 9-cis-epoxycarotenoid dioxygenase gene (NCED) were analyzed.【Result】All treatments advanced the color conversion period and increased the lycopene content of watermelon fruits.Lycopene was detected only in ABA and MnSO4 10 days after pollination,and it was detected in all treatments 17 days after pollination.The accumulation rate of lycopene was fastest at 17-24 days after pollination,and the highest values of 90.78,82.24 and 82.13 μg/g were obtained 38 days after pollination in MnSO4,ABA and MT treatments,respectively,which were significantly higher than that of control (65.00 μg/g).Exogenous substances affected lycopene content via regulating the gene expression of key enzymes involving in lycopene biosynthesis and metabolism.In ABA treatment,the expressions of LCYB1,LCYB2 and LCYE were down-regulated,while MnSO4 induced up-regulation of GGPS1,GGPS2,PSY1,PSY2 and ZDS in main development periods.MT treatment mainly caused significant down regulation of NCED1 and NCED7.【Conclusion】Leaf spraying with MnSO4,ABA and MT could accelerate lycopene accumulation in watermelon fruits.At transcriptional level,ABA treatment mainly reduced conversion rate of lycopene to achieve accumulation of lycopene in watermelon.MnSO4 treatment mainly increased lycopene content by increasing its synthesis rate.MT treatment mainly decreased expression of NCED and decomposition of carotenoids to increase lycopene content.
Key words:  watermelon  lycopene  exogenous substances  metabolizing enzyme gene