3种石斛属植物类胡萝卜素成分及代谢途径分析

Analysis of Carotenoids Compounds and Their Biosynthesis Pathways in Flowers of Three Dendrobium Species

[目的]分析黄色花石斛兰盛开期花瓣中的类胡萝卜素种类和含量,推定石斛属类胡萝卜素合成途径,为探讨黄色花石斛的呈色机理和黄色花育种提供参考。[方法]以花色为黄色的鼓槌石斛、密花石斛和球花石斛的盛开期花瓣和唇瓣为试验材料,采用英国皇家园艺学会比色卡进行花色描述,利用合相色谱串联三重四极杆质谱仪(UPC^2-MS/MS)进行类胡萝卜素定性、定量分析,推测石斛属类胡萝卜素代谢途径。[结果]表明:3种石斛属植物花瓣和唇瓣色系可分为白色系和淡黄-明黄-金黄色系,花瓣和唇瓣中共鉴定出8个类胡萝卜素组分,分别是β-胡萝卜素、α-隐黄质、β-隐黄质、紫黄质、叶黄素、花药黄质、玉米黄质和叶黄素酯化物。定量分析显示:球花石斛白色花瓣中类胡萝卜素含量极少,总量约为52.26μg·g^-1,随着黄色加深,类胡萝卜素总量逐渐增加,球花石斛金黄色唇瓣中的类胡萝卜素总量最高,达到3 810.89μg·g^-1。密花石斛淡黄色花瓣中以叶黄素为主;球花石斛和密花石斛金黄色唇瓣中主要是α-隐黄素、叶黄素和叶黄素酯化物;明黄色鼓槌石斛花瓣中以玉米黄质、花药黄质和叶黄素为主。[结论]α-胡萝卜素及其衍生物是淡黄色和金黄色石斛花瓣中的主要类胡萝卜素成分,而β-胡萝卜素及其衍生物是明黄色石斛花瓣的主要类胡萝卜素成分。结合类胡萝卜素代谢途径,推测通过调控LCYE基因的表达,可实现黄色花石斛的花色定向改良。

[Objective] To investigate the composition content and structure of carotenoids in yellow flower of native Dendrobium species and their biosynthesis pathways, thus proving references for further investigation of the floral pigment mechanism and molecular breeding of Dendrobium.[Method] The flower color in yellow petals and labellum of Den. chrysotoxum, Den. densiflorum and Den. thyrsiflorum were observed according to the Royal Horticultural Society Color Card(RHSCC). Besides, the carotenoids in the petals and labellum in 3 Dendrobium species at full opening stages were determined using UPC^2-MS/MS. Based on the results of UPC^2-MS/MS, the biosynthesis pathways of carotenoids in Dendrobium were proposed.[Result] The result indicated that the floral color of the 3 Dendrobium species could be divided into white group and pale yellow-yellow-golden yellow group. Totally, 8 kinds of carotenoids were detected from the petals and labellum in the 3 Dendrobium species, respectively, including β-carotene,α-cryptoxanthin,β-cryptoxanthin, violaxanthin, lutein, antheraxanthin, zeaxanthin and lutein-5,6-epoxide. According to the results of quantitative analysis, white petals of Den. thyrsiflorum contained the lowest carotenoids(52.26 μg·g^-1). The content of carotenoid increased with the enhancement of yellow color and the carotenoid compounds in the golden yellow labellum of Den. thyrsiflorum was the highest, reaching 3 810.89 μg·g^-1. Among 3 carotenoids contained cultivars, the lutein was majorly contained in pale yellow petals of Den. thyrsiflorum, while golden yellow labellum of Den. densiflorum and Den. thyrsiflorum majorly contained α-cryptoxanthin,lutein and lutein-5,6-epoxide. Yellow petals of Den. chrysotoxum contained violaxanthin, lutein and antheraxanthin.[Conclusion] The carotenoids in pale yellow and golden yellow petals are mainly α-carotene and its derivatives, while that in bright yellow petals are mainly β-carotene and its derivatives. Regulation of the LCYE genes which may cause carotenoid biosynthesis will result in flower color change in yellow flower of Dendrobium.