Analysis of cuticular wax constituents and genes that contribute to the formation of 'glossy Newhall', a spontaneous bud mutant from the wild-type 'Newhall' navel orange
Analysis of cuticular wax constituents and genes that contribute to the formation of 'glossy Newhall', a spontaneous bud mutant from the wild-type 'Newhall' navel orange
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DOI：
10.1007/s11103-015-0343-9
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发表时间：
2015-08-01
影响因子：
5.1
通讯作者：
Liu, Yong
中科院分区：
文献类型：
--
作者：
Liu, Dechun;Yang, Li;Liu, Yong
橙子（柑橘[L.] Osbeck）果实表面含有大量的表皮蜡，其具有重要的生理生态作用，如保水和病原体防御。成熟脐橙橙子的蜡质成分研究较多，但果实发育过程中蜡质成分的变化及其生物合成/输出的分子机制尚未见报道。最近，我们报道了一个自发芽突变体从野生型（WT）'纽荷尔'脐橙橙子。这种突变体表现出不寻常的光泽果皮，并被命名为'光泽纽荷尔'（MT）。在这项研究中，我们比较了WT和MT果实表面上的表皮蜡和表皮内蜡的发育概况。研究表明，脐橙橙子表面表皮蜡晶体的形成取决于大量脂肪族蜡成分和微量萜类化合物的积累。与此形成鲜明对比的是，下表皮内蜡层具有相对低浓度的脂肪族蜡组分，但高浓度的环状蜡化合物，特别是在果实发育后期的萜类化合物。我们的工作还表明，许多参与蜡的生物合成和输出途径的基因在MT果皮中下调，导致脂肪族蜡组分的数量减少和上表皮蜡晶体的损失，最终导致MT果实的光泽表型。
Navel orange (Citrus sinensis [L.] Osbeck) fruit surfaces contain substantial quantities of cuticular waxes, which have important eco-physiological roles, such as water retention and pathogen defense. The wax constituents of ripe navel orange have been studied in various reports, while the wax changes occurring during fruit development and the molecular mechanism underlying their biosynthesis/export have not been investigated. Recently, we reported a spontaneous bud mutant from the wild-type (WT) 'Newhall' Navel orange. This mutant displayed unusual glossy fruit peels and was named 'glossy Newhall' (MT). In this study, we compared the developmental profiles of the epicuticular and intracuticular waxes on the WT and MT fruit surfaces. The formation of epicuticular wax crystals on the navel orange surface was shown to be dependent on the accumulation of high amounts of aliphatic wax components with trace amounts of terpenoids. In sharp contrast, the underlying intracuticular wax layers have relatively low concentrations of aliphatic wax components but high concentrations of cyclic wax compounds, especially terpenoids at the late fruit developmental stages. Our work also showed that many genes that are involved in wax biosynthesis and export pathways were down-regulated in MT fruit peels, leading to a decrease in aliphatic wax component amounts and the loss of epicuticular wax crystals, ultimately causing the glossy phenotype of MT fruits.