蜜橘乙烯利处理后果皮不同部位着色差异的研究

Study on Differences of Coloration Process in Different Parts of Ethephon-degreened Mandarin Fruit

以无核‘南丰蜜橘’为试材,对其采后乙烯利褪绿过程中果皮不同部位着色差异现象进行研究。结果表明,褪绿过程中,果蒂部位着色快于赤道部位,该现象可以归因于这两个部位果皮叶绿素含量和类胡萝卜素含量的差异。进一步分析表明,乙烯利处理后,果蒂部位叶绿素a和叶绿素b降解快于赤道部位;果蒂部位橙色色素物质(以β–隐黄质为主)的积累高于赤道部位,而赤道部位黄色色素(以叶黄素为主)的积累高于果蒂部位,导致果蒂部位橙色深于赤道部位。褪绿关键期(贮藏3d时),果蒂部位叶绿素a/b相互转化相关基因CitNYC、叶绿素降解关键基因CitChlase、类胡萝卜素生物合成调控基因CitPDS、类胡萝卜素合成途径下游基因CitCHYB、CitNCED1和CitNCED2的表达水平均显著高于赤道部位(P <0.05)。这些基因表达水平的差异可以在一定程度上解释乙烯利处理后蜜橘果蒂和赤道两个部位果皮色素的变化。

The gradient coloration of ethylene-degreened mandarin fruit was studied.The results indicated that the coloration process of stem end position of the peel was faster than the equator position during the degreening process.The difference of chlorophyll content and carotenoid content of these two positions could well explain this phenomenon.Further studies indicated that the degradation of chlorophyll a and chlorophyll b in the stem end position of ethylene-degreened mandarin fruit was faster than that in the equator position,more orange-colored carotenoids(mainlyβ-cryptoxanthin)were synthesized in the stem end position of ethylene-degreened mandarin fruit,while more yellow-colored carotenoids(mainly lutein)were synthesized in the equator position.The different expression levels of some regulatory genes in chlorophyll and carotenoid metabolism(including CitChlase,CitNYC,CitPDS,CitCHYB,CitNCED1 and CitNCED2)could explain the pigment changes of these positions to some extent.