贮藏温度对采后蜜橘果皮转色过程中质体结构及相关基因表达的影响

Effects of Storage Temperature on Plastid Structure and Related Gene Expression During Coloring of Mandarin Fruit Peel After Harvest

温度是调控采后柑橘果实着色的主要环境因素之一。以重庆北碚产早熟蜜橘(绿熟)为实验材料,研究5、25、32℃贮藏对蜜橘果皮色泽、质体结构及相关基因表达的影响。结果表明:在第9天时,不同贮藏温度下蜜橘果实表现出显著的着色差异,5℃贮藏下果实色差指数没有显著变化,果皮呈绿色;25℃贮藏果实的C^(*)、a^(*)/b^(*)值显著增加,H^(*)值显著下降,果皮由绿转黄;32℃贮藏的果C^(*)、a^(*)/b^(*)值有轻微增加,H^(*)值无显著变化,果皮保持绿色。超微结构分析表明:果实采收时果皮油胞呈椭圆形,出现油胞腔,质体结构完整,质粒片层清晰可见,质体内分布少量质体小球。5℃贮藏延缓了蜜橘果皮油胞结构的变化,质体相关基因CcISPH1、CcISPH2、CcISPH3以及CcCRR22表达水平较低,叶绿体变化缓慢;25℃贮藏果实的果皮油胞形态逐渐解体,CcISPH1、CcISPH3以及CcCRR22上调表达,促使叶绿体发育分化为有色体;32℃贮藏果实的果皮油胞层状结构解体,呈半真空状态,CcISPH3、CcHSP17.6II分别在贮藏的第3天和第6天上调表达,CcCRR22下调表达,叶绿体分化成有色体后再分化为叶绿体。实验结果旨在为进一步理解贮藏温度调控采后柑橘果实着色的机理提供一定的理论参考。

Temperature is one of the main environmental factors that regulate the coloration of citrus fruits after harvest.The effects of storage temperature of 5℃,25℃and 32℃on the peel color,the plastid structure and the expression levels of related genes of early-ripening mandarin fruits(green ripening)produced in Chongqing Beibei were studied.The results showed that on the 9th day,the fruit showed significant coloring differences under different storage temperatures,and the color index of the fruits stored under 5℃did not change significantly,and the color of peel was green.C^(*)and a^(*)/b^(*)of the fruit stored at 25℃increased significantly,H^(*)decreased significantly,and the peel color changed from green to yellow.C^(*)and a^(*)/b^(*)of the fruit stored at 32℃increased slightly,and the peel remained green without significant change in H^(*).Ultrastructural analysis showed that the peel oil gland was oval when the fruit was harvested.The oil lumen,a complete plastid structure and the plasmid layer were clearly visible,and a small number of plastoglobulus were distributed in the plastid.Storaged at 5℃delayed the change of the structure of peel oil gland,and the expression levels of plastid-related genes CcISPH1,CcISPH2,CcISPH3 and CcCRR22 were low,and the chloroplasts changed slowly.The peel oil gland morphology of fruits stored at 25℃gradually disintegrated,and the up-regulated expression of CcISPH1,CcISPH3 and CcCRR22 promoted the development and differentiation of chloroplasts into chromoplast.The peel oil gland-layer structure of the 32℃stored fruit disintegrated,showing a semi-vacuum state,and CcISPH3 and CcHSP17.6II were up-regulated on the 3rd and 6th day of storage,while the expression of CcCRR22 was down-regulated.And chloroplasts differentiated into chromoplast and then differentiated into chloroplasts.The experimental results aimed to provide some theoretical reference for well understanding the regulation mechanism of temperature on the coloration of postharvest citrus fruit.