Study On Characteristic And Transcriptional Regulation Of Anthocyanin Accumulation In Ornamental Kale

Ornamental kale(Brassica oleracea L.var.acephala DC)is a biennial herbaceous foliage plant cultivated around the world.It is grown mainly for its showy inner leaves,which are white,pale yellow,pink,red,or purple.Ornamental kale is widely cultivated from late autumn,through winter,to early spring due to its ability to endure low temperatures.The colorful leaves not only have ornamental value,but are also beneficial to human health due to their rich carotenoid and anthocyanin content.To investigate the relationship between the degree of coloration and anthocyanin pigments distribution,content and composition,and the regulation of the related transcription factors in the process of the anthocyanin synthesis in ornamental kale,microscopy observation,spectrophotometer method,high-performance liquid chromatography-mass spectrometry(HPLC-MS)analysis and semi-quantitative RT-PCR technique were used for this study.The major results are showed as follows:1.The fresh tissues revealed that pink,red,purple,and purple-black coloration were associated with anthocyanin,and black purple were the result of the combination of anthocyanins and chlorophyll.In the colored cultivars,anthocyanins were abundant mainly in the first and second cell layers below the epidermis in both the hypocotyls and inner leaves and no anthocyanin was found in 'White 9'.2.In the colored cultivars,the leaf colour deepened with the increase of content of anthocyanin as a whole.As a consequence,in the condition that absence of photosynthetic pigment,the leaf colour deepened from pink to purple-black with the increase of anthocyanin content.Leaf colour of 'Black 10' was purple-black as a result of anthocyanin and chlorophyll existed in and no anthocyanin existed in 'White 9' made with the white leaf.3.Eight anthocyanins were identified in the four colored cultivars,including one non-acylated,four monoacylated,and three diacylated cyanidin glycosides.Cyanidin-3-(sinapoyl)(feruloyl)-diglucoside-5-glucoside is the most abundant anthocyanin in the four colored cultivars followed by cyanidin-3-(sinapoyl)-diglucoside-5-glucoside.4.The anthocyanin biosynthetic transcription regulatory factor BoMYB2 expressed in both red and pink phenotypes,and the expression quantity in the red phenotype was significantly higher than the pink phenotype.BoMYB1 and BobHLH1 only expressed in red phenotype.We speculated that BoMYB2 played a key role of anthocyanin accumulation,while BoMYB1 and BobHLH1 palyed micro regulation function.The results not only provided basic data for breeding programs and genetic studies of ornamental kale,but also provided information for the related research of flower colour in garden plant.