Difference Analysis Of Quality Based On Omics And Storage Properties Research Of Coix Seed

Coix(Coix lacryma-jobi L.var.ma-yuen Stapf)is an ancient food and cash crop.There are many varieties of coix and the differences between different varieties are greater in seed structure,size and nutrient composition.In general,the quality of wild coix seeds(WC)is better than that of cultivated coix seeds(CC).The primary performance is that WC is generally larger than CC and the shell of WC is harder.In addition,the content of protein,fat and amino acids of WC is also higher than that of CC.In recent years,with the improvement of breeding technology and the increase of market demand,the planting area and yield of coix seed have increased year by year.But as a small variety of grains crops,compared with most cereals,it is more prone to deterioration and aging during storage,resulting in the decline in quality and economic benefits.Therefore,it is of great theoretical significance and application value to study the molecular regulation mechanism of WC and CC nutrition differences and explore the quality deterioration mechanism of coix seed during storage.This study explored the differences in nutrients between WC and CC from the level of transcription and protein to provide a theoretical basis for improving the nutritional quality of cultivated coix by using RNA-seq and iTRAQ technology.At the same time,the two-dimensional gel electrophoresis and mass spectrometry were used to explore the changes in the protein of CC during storage,aiming to further understand the mechanism of aging and provide guidance for scientific and reasonable storage of coix.The preliminary results showed as follows:(1)RNA-seq technology was used for transcriptome analysis of WC and CC.Through deep sequencing,unigenes assembled by de novo was analyzed for functional annotation and differential expression.With FDR<0.05 and |log2FC|>1 as filter criteria,10,921 up-regulated proteins and 9,118 down-regulated proteins were obtained.GO and KEGG functional annotation and qPCR validation of all differentially expression genes(DEGs)were carried out.The results showed as follows:? 1,444 DEGs were enriched in 124 Pathways,among which the p-value<0.05 and q-value<0.05 were 11 and 8.A total of 35 pathways were related to the metabolism and biosynthesis of major nutrients in coix seed,including flavonoid biosynthesis,flavonoid and flavonol biosynthesis,unsaturated fatty acid biosynthesis,fatty acid degradation,fatty acid biosynthesis,a-linolenic acid metabolism,linoleic acid metabolism,starch and sucrose metabolism,various amino acid metabolism,etc.?Compared with WC,F3H,LAR,ANR,and UFGT involved in flavonoid biosynthesis in CC were down-regulated.? SPS and SS were up-regulated genes and also the key enzymes involved in the sucrose metabolism pathway.There was a positive correlation between SPS activity and sucrose accumulation in plants and there was a negative correlation between SPS activity and starch accumulation.? LKR/SDH was the most important enzyme in lysine degradation pathway.Overexpression of LKR/SDH accelerated the degradation of lysine and was not conducive to the accumulation of lysine in CC.(2)In this study,iTRAQ technology was used to detect the proteins in WC and CC during filling.A total of 2,715 proteins were identified.417 proteins were identified as the differentially expressed proteins(DEPs)at p-value<0.05 and difference ratio reaches>1.2 according to the protein level of abundance,which included 253 displaying increased abundance levels and 164 displaying decreased abundance levels.All of DEPs were analyzed by GO and KEGG enrichment,and a global correlation analysis were performed between DEPs and DEGs in order to screen out the proteins related to the nutrition difference of coix seed.The results showed as follows:? A total of 220 DEPs enriched in 88 pathways were detected.Pathways with p-value?0.05 included starch and sucrose metabolism,tryptophan metabolism,and arachidonic acid metabolism.? According to the association analysis,141 proteins could matched to transcripts and the expression of 103 proteins were consistent with the transcriptome.The metabolic processes involved in the associated proteins mainly included amino acid metabolism,biosynthesis of other secondary metabolites,lipid metabolism,carbohydrate metabolism,energy metabolism,etc.? 21 DEPs,involved in starch and sucrose metabolism,were changed by using iTRAQ analysis.GBE2 and GPA were down-regulated proteins,and BGLU,AMY and UXS were up-regulated proteins.The expression patterns of unigene0037437(AMY)and unigene0045956(BGLU)were consistent with the level of transcription.? Compared with WC,enzymes involved in fatty acid degradation were up-regulated in CC,which promoted the degradation of fatty acids in CC.? Two of HTPRs involved in the lysine synthesis pathway were down-regulated,which resulted in a decrease in lysine content and also affected threonine levels.(3)In order to understand the underlying mechanism of quality aging during storage of coix seed,two-dimensional gel electrophoresis and mass spectrometry were used to analyze the changes of protein at 1,5,and 10 months during storage.The results showed as follows:? Thirty one differentially expressed proteins were detected which involved seven pathways including starch and sucrose metabolism,carbon metabolism,RNA transport,proteasome,protein processing in endoplasmic reticulum,ribosome,and RNA degradation.? Sucrose synthase 1 was associated with sucrose metabolism and affected the sucrose content during the storage.? Increased ambient temperature enhanced respiration of coix after 5 month storage,and overexpression of aconitate hydratase 2 promoted the generation of energy.? The proteins involved in the antioxidant system and resistance stimulus of coix seed were mostly up-regulated during storage.