| Chinese cabbage(Brassica rapa L.ssp.pekinensis)is native to China and is one of the main vegetables during the fall and winter in northern China.In recent years,with improved demand in quality of Chinese cabbage,purple Chinese cabbage varieties have come out one after another.Compared with non-purple Chinese cabbage varieties,Purple Chinese cabbage is not only colorful,but also rich in anthocyanin that has health value.So far,there is no report about purple Chinese cabbage.8 purple-heading Chinese cabbage hybrids were used as experiment materials in this study.Ratio of purple height to head height(RPH),content of anthocyanin in the innermost,middle and external head leaves and the oxidation resistance in the innermost head leaves have been measured.the related genes of anthocyanin synthesis pathway in the innermost head leaves have been quantitatively analyzed.The results are as follows:1.In different Chinese cabbage materials,the contents of anthocyanin have significant differences in the innermost,middle and external head leaves.The anthocyanin content in any part of purple-heading Chinese cabbage is higher than that of ordinary Chinese cabbage.For purple-heading Chinese cabbage hybrids,anthocyanin content in the core head leaves is the highest and much higher than that in the middle and external head leaves.The correlation analysis shows that,the anthocyanin content in the middle head leaves was significantly correlated with that in the innermost head leaves,but the anthocyanin content in the external head leaves was not significantly correlated with that in innermost and middle head leaves.Therefore,the main part of anthocyanin accumulation is the core of the head.The accumulation of anthocyanin in the core head leaves may affect the anthocyanin accumulation in the middle of the head.The accumulation pattern of anthocyanin in the outer head leaves may be different from that in the innermost and middle leaves of the head.2.In different purple-heading Chinese cabbage hybrids,the range of anthocyanin distribution is different.The RPH is from 0.37 to 0.60.The RPH is significantly correlated with the anthocyanin content in the core and middle head leaves and not significantly correlated with the anthocyanin content in the external head leaves.Results show that the coloration of purple-heading Chinese cabbage is mainly caused by the combined effect of anthocyanin accumulation in the core and middle head leaves.The anthocyanin content in outer leaves of the head may not have a significant effect on RPH of purple-heading Chinese cabbage,because the anthocyanin content in this site is too low.The RPH can be used as a simple indicator to measure the anthocyanin content in the core and middle head leaves of purple-heading Chinese cabbage.3.A total of 19 anthocyanin components were identified of the innermost head leaves in different purple-heading Chinese cabbage hybrids by liquid chromatography and mass spectrometry.Among them,14 were cyanidins,accounting for 74% of the total anthocyanins.There are two anthocyanins that can be identified in all purple-heading Chinese cabbage hybrids,indicating that these two anthocyanins are common ingredients of the purple-heading Chinese cabbage hybrids.The anthocyanin components identified in different purple-heading Chinese cabbage hybrids are different.Therefore,in different materials,the anthocyanin metabolism may be different.4.The total antioxidation and capability of scavenging hydroxyl free radicals of anthocyanin in the core head leaves were analyzed in purple-heading Chinese cabbage hybrids.The total antioxidant capacity and hydroxyl radical scavenging rate of the anthocyanin extract in the core head leaves of purple-heading Chinese cabbage hybrids were higher than that in ordinary Chinese cabbage.As displayed in the correlation analysis,the total antioxidant and hydroxyl radical scavenging rate of anthocyanin extract in the core of the head were significantly correlated with the anthocyanin content of same site,In addition,the total antioxidant capacity and hydroxyl radical scavenging rate were also significantly correlated.Therefore,the anthocyanin in the purple-heading Chinese cabbage is an excellent natural antioxidant.5.As indicated in the Real-time quantitative PCR analysis,the relative expression of the structural genes Br ANS、Br LODX、Br GST and Br UFGT-2 in the anthocyanin synthesis pathway were significantly correlated with the anthocyanin content in the core leaves of purple-heading Chinese cabbage hybrids.It is suggested that the structural genes Br ANS,Br LODX,Br GST and Br UFGT-2 are involved in the regulation of the anthocyanin accumulation in purple-heading Chinese cabbage and affecting the coloration of Chinese cabbage.But,the relative expression of Br F3’H,Br DFRand Br UFGT-1 were not significantly correlated with the anthocyanin content in the core leaves of purple-heading Chinese cabbage hybrids.The relative expression of regulatory genes Br MYB2,Br MYB2 and Br EGL31 were not importantly correlated with the anthocyanin content in the core leaves of purple-heading Chinese cabbage hybrids. |
