Preliminary Analyses Of Pod Dehiscence And Its Associated Gene Functions In Soybean

Pod dehiscence is an important agronomic trait.Pod dehiscence would cause huge yield losses before soybean maturity.In order to reduce the yield loss caused by pod dehiscence in soybean,breeders have selected some soybean accessions with pod shattering resistance through hybridization.Although some of soybean pod dehiscence associated genes have been identified,the underlying mechanism of pod dehiscence is still not comprehensively explained.Moreover,the regulation network of soybean pod dehiscence needs to be further improved.We have analyzed characteristics of pod dehiscence from 56 soybean accessions including wild,landrace and cultivated soybeans.Five kinds of shattering-resistant and shattering-susceptible soybean accessions were chosen separately.Both sequence variation and gene expression pattern of the known pod dehiscence associated genes were analyzed in these soybean accessions.For getting more soybean pod dehiscence related genes,we have identified differentially expressed genes(DEGs)between shattering-resistant and shattering-susceptible soybean accessions based on transcriptome analyses of these 10 soybean accessions.Long non-coding RNAs(lncRNAs)that may be involved in soybean pod dehiscence were also identified,and we constructed co-expression networks between mRNAs and lncRNAs.RNA sequencing results were further verified by real-time PCR.Furthermore,DEGs were screened through analyzing positions of soybean pod dehiscence quantitative trait locus(QTLs)and phenotypes of soybean pod dehiscence for achieving poddehiscence candidate genes.Our main findings are as follows:(1)Characteristics of pod dehiscence in 56 soybean accessionsThrough measuring fruit cracking force and percentages of dehisced pods on 56 soybean accessions,our results showed that the average of fruit cracking force was between 5.592 N and 18.109 N,the average of percentages of dehisced pods was between 0.67% and 99.29%,and the fruit cracking force of wild soybeans(5.741 N)was remarkably lower than that of both landrace soybeans(11.366 N)and cultivated soybean(11.569 N),and the percentages of dehisced pods in wild soybeans(91.03%)was distinctly higher than that of both landrace soybeans(40.01%)and cultivated soybeans(45.01%).Five shattering-susceptible soybeans accessions and five shattering-resistant soybeans accessions were obtained after further screening,which would be used for studying the potential mechanism of soybean pod dehiscence.(2)Sequence variation and gene expression pattern of known pod-dehiscence genes between shattering-resistant and shattering-susceptible soybean accessionsAfter analyzing both expression pattern and sequence variation for two poddehiscence associated genes(SHAT1-5 and Pdh1)in 10 soybean accessions,we found that there was not a notable correlation among the 20 bp insertion-deletion(indel)inside promoter,expression pattern of SHAT1-5 and pod dehiscence.However,both genotype and transcriptional level of Pdh1 were in accordance with the poddehiscence phenotypes of selected soybean accessions.(3)Transcriptome analyses on both shattering-resistant and shatteringsusceptible soybean accessionsWe have identified 225 DEGs through transcriptome analyses on 10 selected soybean accessions.Besides nutrient-related genes,nearly half of genes functions were related to hydrolase activity by molecular function module from Gene Ontology analysis,including hydrolyzing both O-glycosyl compound and glycosyl bonds.After analysis on DEGs,we have obtained 16 DEGs whose functions regarding pod dehiscence are unknown,and those DEGs are selected as pod-dehiscence candidate genes.By analyzing the positional relationship between DEGs and pod dehiscence QTLs,18 DEGs were found to be located inside pod dehiscence QTLs.Glyma19G231900 encoding an ?/?-hydrolase,could be an ideal pod-dehiscence candidate gene in soybean.We also identified 679 lncRNAs,and 69 co-expression networks between mRNAs and lncRNAs were constructed.The gene expression pattern of the darkorchid2 module was consistent with the pod-dehiscence phenotype of selected soybeans,indicating that it is an ideal resource used for soybean poddehiscence research.In conclusion,we have obtained a large number of genes related to soybean pod dehiscence,which provides reference for improving the genetic regulation network,and provides new sight for molecular breeding of soybean pod dehiscence.