桑椹成熟期间1-脱氧野尻霉素和主要花青素含量及相关基因表达的变化规律研究

Changes in Contents of 1-Deoxynojirimycin and Main Anthocyanins and Expression of Related Genes in Mulberry Fruit During Maturation

桑椹具有较高的营养价值和保健功能,其主要生物活性成分包括生物碱1-脱氧野尻霉素(1-deoxynojirimycin,DNJ)以及矢车菊素-3-葡萄糖苷(cyanidin-3-O-glucoside,C3G)和矢车菊素-3-芸香糖苷(cyanidin-3-O-rutinoside,C3R)等花青素。利用高效液相色谱法检测桑椹成熟期间DNJ、C3G、C3R含量,用实时荧光定量PCR法检测相关基因表达水平的变化情况。结果显示,在桑椹变红前,DNJ含量较高,质量分数最高达到0.246%,但C3G和C3R未能被检测到;随着桑椹的成熟,DNJ含量迅速下降,到完全成熟后质量分数仅有0.006%,而C3G和C3R含量逐渐升高并趋于稳定,最终C3G质量分数稳定在1%左右,C3R质量分数稳定在0.6%左右。DNJ合成路径上相关的赖氨酸脱羧酶(lysine decarboxylase,LDC)和铜胺氧化酶(copper amine oxidase,CAO)编码基因LDC、CAO1、CAO2、CAO4的表达量在桑椹未变红前为逐渐升高,后迅速下降,而CAO3表达量一直逐渐降低;花青素合成关键酶基因4CL和CHI表达量在桑椹变红前逐渐升高,后迅速降低,而CHS表达量在桑椹变红前较低,后迅速升高并持续维持较高水平。研究结果不仅为药用桑椹的采收提供了指导,也为果桑分子育种提供了理论依据。

Mulberry fruit has high nutritional and medical value,whose major bioactive components include 1-deoxynojirimycin(DNJ),cyanidin 3-O-glucoside(C3G)and cyanidin 3-O-rutinoside(C3R).In this paper,contents of DNJ,C3G and C3R in mulberry fruit during maturation were detected by high performance liquid chromatography and expression levels of synthesis related genes were measured by qRT-PCR.As the results indicated,prior to maturation,DNJ content was higher with the highest level of 0.246%,while contents of C3G and C3R were nondetected.Then,DNJ content decreased rapidly with maturation of mulberry fruit and finally dropped to 0.006%after maturation,while contents of C3G and C3R increased gradually and finally kept unchanged with C3G content of almost 1%and C3R content of almost 0.6%.Expression levels of DNJ synthesis-related genes LDC,CAO1,CAO2 and CAO4,encoding lysine decarboxylase(LDC)and copper amine oxidase(CAO),increased gradually before mulberry fruit turned red,and then decreased rapidly,while expression level of CAO3 kept declining gradually.Expression levels of anthocyanin-synthesis related key enzyme genes 4 CL and CHI increased gradually before mulberry fruit turned red,whereas decreased rapidly later In contrast,expression level of CHS was lower before mulberry fruit turned red,and then climbed up rapidly and kept high.This study can not only provide guidance for harvest of medicinal mulberry,but also provide theoretical basis for molecular breeding of mulberry.