Identification Of Castor WD40 Protein Family And Preliminary Study On Regulatory Function Of RcTTG1 On Fatty Acid Synthesis

Castor(Ricinus communis L.)is widely cultivated in many countries as an important industrial energy crop because of its strong adaptability to environment and rich ricinoleic acid content in its seeds.Ricinoleic acid is D-12-hydroxy octadecyl-cis-9-enoic acid(Δ 9cis 1 8:1-OH12),which is different from other edible or industrial plant fatty acids and has excellent physical and chemical properties due to its unique hydroxyl structure.The gene expression of the hydroxylated fatty acid biosynthesis pathway is spatiotemporal specific during seed development,which implies that compared with other oilseed plants,castor may have a more specialized fatty acid synthesis regulation mechanism.WD40 repeat proteins in plants are the platform of protein-protein and protein-DNA interactions,which regulate many plant growth processes,including seed development,in a non-catalytic manner.In order to systematically analyze the potential function of WD40 protein in castor seed development and fatty acid accumulation,we identified the WD40 family in castor at the whole genome level using the bioinformatics technique.The regulation of WD40 family during castor seed development was investigated by temporal and spatial expression analysis,and the potential negative regulation of RcTTG1 gene,an important member of RcWD40s,on ricinoleic acid accumulation was predicted.The main conclusions of this study are as follows:1.According to the annotation of castor genome,182 members of RcWD40 family were identified by Hmmer search and WD40 domain database(Pfam and SMART).They are named RcWD40-1 to RcWD40-182 based on their position on chromosomes,and their physicochemical properties are predicted.2.We co-constructed an evolutionary tree of WD40 proteins from Castor and Arabidopsis.According to the tree topology,RcWD40s was divided into 8 clusters.The RcWD40s are divided into 28 sub families according to the composition of the protein domain,which indicates that the members of the RcWD40s are not conservative except for the WD40 domain.3.RNA-seq analysis of different tissues or parts revealed different expression patterns of RcWD40 family genes in flower,leaf,root,stem and seed of castor.The regulation of RcWD40s on seed development was revealed by the analysis of seed development stage.4.The family member RcTTG1 gene was identified and cloned.RcTTGl and ricinoleic acid synthesis key enzymes or key positive regulatory factors are different in expression patterns,and they show a negative correlation overall,so we predict that RcTTG1 has a potential negative regulatory role for ricinoleic acid accumulation.