Molecular Regulation Mechanism Of Light Signal Induced Anthocyanin Biosynthesis In Light-Insensitive Eggplant

Eggplant(Solanum melongena L.)is one of the most important vegetable crops in the world.However,low temperature and poor light condition in early spring often lead to the poor coloring of eggplant and affect the quality of eggplant fruit.Anthocyanins are secondary metabolites in higher plant which can determine the color of purple eggplant fruit.Light is one of the most important environmental factor affecting the anthocyanin biosynthesis.We obtained the light-insensitive(anthocyanin)eggplant by shading treatment.Based on the qRT-PCR validation and analysis towards DEGs,we found a series of genes may take part in the anthocyanin biosynthesis under darkness and light.More exploration towards anthocyanin biosynthesis in light-insensitive eggplant can provide theoretical basis for the breeding of shade tolerance species.Firstly,according to the statistical results of shading treatment,the eggplant germplasm resources were divided into two types: light-sensitive and light-insensitive type and the proportion of light-sensitive type account for 92%.We selected the NO.145 material for further study.The anthocyanin content in the peel of control group was about 83.1% of eggplant peel under natural conditions.The main component of anthocyanin in the peel of both control group and natural group was identified as delphinidin-3-rutinoside by LCMS.The shading condition did not affect the main kind of anthocyanin in the peel of the NO.145 material.Secondly,12 samples were sequenced by Illumina Hiseq platform,producing 4.45 Gb data for each sample.It was found that the circadian rhythm,flavonoid biosynthesis and anthocyanin pathway were enriched in the DEGs(FDR?0.001 and |log2 Ratio|?1)with the gene ontology and KEGG pathway analysis.Thirdly,by the analysis of different expression genes,the expression level of Phototropin1(SmPHOT1)and PhytochromeB(SmPHYB)decreased when the bagged materials were exposed to light from 0 h to 0.5 h.After analyzing the expression patterns of transcription factors,we found that the expression level of SmMYB1 and SmTT8 were significantly down-regulated,we proposed that SmMYB1 and SmTT8 could activate the downstream structural genes responsible for anthocyanin biosynthesis in the darkness.The expression level of most structural genes indicated that darkness did not restrain the transcriptional level of structural genes and light can affect the transcriptional level of structural genes related to anthocyanin biosynthesis.