Functional Analysis Of Photomorphogenesis Proteins SmCOP1L And SmCIP7 In Fruit Development And Surface Coloration Of Eggplant (Solanum Melongena L.)

Eggplant(Solanum melongena L.)is an important vegetable crop widely cultivated in the world.The anthocyanin of eggplant peel is an important beneficial component for human health.At present,most of the cultivated eggplant varieties in China show poor adaptability to the weak light conditions.The results showed that eggplant peel was unevenly colored,which led to the decline of fruit quality.Therefore,most eggplant cultivated varieties used in China are imported from abroad,which is very unfavorable to the sustainable development of the domestic eggplant industry and the strategic safety of seeds.Eggplant germplasm is an important factor that restricts the development of the whole industry at present,and the molecular genetic mechanism of light regulating the development and coloration of eggplant fruits can provide theoretical guidance for the future breeding of high-quality materials.In this paper,the purple long eggplant "san yue qie" with complete light-dependent anthocyanin synthesis was used as material,the function of light morphogenesis regulators SmCOP1 L and SmCIP7 in fruit development and surface coloration was analyzed by qRT-PCR,genetic transformation,high performance liquid chromatography and transcriptome.The main research work is as follows:1)The expression of anthocyanin biosynthesis and regulation genes SmCHS,SmDFR,Sm3 GT,SmMYB1,SmTT8,SmCOP1 L,SmCOP1,SmCIP7,SmCRY1,SmCRY2 and SmHY5 under light or dark conditions were analyzed by qRT-PCR.It was found that light could strongly induce the transcriptional levle of SmCHS,SmDFR,Sm3 GT,SmMYB1,SmTT8 and SmCOP1 L.2)The accumulation of anthocyanins in different tissues of eggplant(root,stem,leaf,flower,peel and flesh)and the expression of anthocyanin biosynthetic and regulatory genes were analyzed by pH differential method and qRT-PCR,respectively.It was found that the tissue distribution of anthocyanins was highly correlated with the expression patterns of biosynthetic and regulatory genes SmCHS,SmDFR,Sm3 GT,SmMYB1 and SmCOP1 L.3)By cloning and bioinformatics analysis of SmCOP1 L,we found that the open reading frame contains 2013 nucleotides,encoding 670 amino acids,and has typical RING-finger,Coiled coil and WD40 domains.Through bioinformatics analysis of SmCIP7 sequence in eggplant genome database,it was found that its open reading frame contained 3201 nucleotides,encoding 1066 amino acids,and had DNA topoisomerase II domain at the C-terminal.It was speculated that SmCIP7 might play a role in regulating the advanced structure of DNA.4)SmCOP1L and SmCIP7 gene-specific silencing lines were successfully obtained by RNAi and agrobacterium-mediated genetic transformation.We found that the silence of SmCOP1 L resulted in the up-regulation expression of anthocyanin biosynthetic genes,which promoted anthocyanin accumulation.In addition,the up-regulation of SmMYB1 increases the transcription levels of SmCOP1 and SmCOP1 L in SmMYB1-overexpressing lines.However,the silence of SmCIP7 results in the down-regulation expression of anthocyanin biosynthetic genes and the reduction of anthocyanin biosynthesis.Besides,the silence of SmCIP7 also resulted in the decrease of fruit size,the decrease of chlorophyll content in peel,the increase of chlorogenic acid content in flesh and the decrease of seed number.5)The DEGs of fruits in wild type and SmCIP7-RNAi lines were analysed by RNA-seq,357 DEGs were found,of which 160 were up-regulated and 197 were down-regulated.GO functional enrichment divided them into 41 functional groups;KEGG pathway analysis had 78 significant enrichment pathways,of which the most significant down-regulated pathways was flavonoid biosynthesis pathways.Further analysis revealed that those genes annotated as anthocyanin structural genes including SmCHS,SmCHI,SmF3 H,SmF3'5'H,SmDFR and SmANS,regulatory genes including SmCIP7 and SmTT8 were down-regulated.In addition,some differentially expressed genes,such as,SmUDPG1 and SmSCL13,may be involved in eggplant fruit development.In this paper,the function and molecular mechanism of light morphogenetic factors SmCOP1 L and SmCIP7 in fruit development and coloration were preliminarily analyzed,which provided a theoretical basis for future molecular breeding of high-quality cultivated eggplant.