title: 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.
abstract: 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.
authors.affiliation: Department of Pomology, College of Agronomy, Jiangxi Agricultural University, Nanchang, 330045, China.
authors.forename: Dechun
authors.initials: D
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zheng
authors.forename: Yuechen
authors.initials: Y
authors.lastname: Wang
authors.forename: Minli
authors.initials: M
authors.lastname: Wang
authors.forename: Xia
authors.initials: X
authors.lastname: Zhuang
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.forename: Chuanfu
authors.initials: C
authors.lastname: Liu
authors.forename: Shanbei
authors.initials: S
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
mesh_terms: D001692:Biological Transport; D032084:Citrus sinensis / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000378:metabolism / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014885:Waxes / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014885:Waxes