Identification of Differentially Expressed Genes in Grape Skin at Veraison and Maturity and Construction of Co-expression Network

The ripening process of grape is an important stage during grape growth and development. During this process, color of grape skin is the most obvious change. The molecular mechanism for the ripening of grape(a non-climacteric fruit, which ripens without ethylene and respiration bursts) is still unclear. Although numerous studies have been done on the changes in the contents of metabolites during grape ripening, the differentially expressed genes at veraison and maturity stages have not been systematically analyzed. In this study, 1 524 genes that are significantly differentially expressed in grape(Pinot Noir) skin at veraison and maturity stages were identified, and a co-expression network of these genes was built. Some of the eight co-expression modules we identified may be closely related to the synthesis or metabolism of anthocyanins, sugar acids, and other flavor substances. The transcription factor families WRKY, b ZIP, HSF and WOX may play an important role in the regulation of anthocyanin synthesis or metabolism. The results provide a foundation for further study of the molecular mechanism of grape ripening.

Research on the Necessity of Building National-level Grape and Cherry Germplasm Resources Bank in Shandong Province

At present,the grape and cherry industries in Shandong are in the leading position in China and have driven the development of related high-end manufacturing industries such as wine,brandy,preserved fruit processing,fruit juice processing and health products. Therefore,vigorously developing the grape and cherry industries in Shandong Province and carrying out development and innovation are important parts of Shandong Province in responding to the strategy of national new and old kinetic energy conversion. However,currently the germplasm resources preserved in the fruit tree resources banks in China are only 45% of those in the US and 27. 2% of those in the EU. Moreover,the development of fruit trees resources banks in Shandong is relatively backward in China,and there is still no banks related with grape and cherry germplasm resources in Shandong. Therefore,importance can be attached to the agriculture,forestry,and animal husbandry to build germplasm resources banks for grape and cherry industries in Shandong Province. Building the national-level grape and cherry germplasm resources bank in Shandong Province can also promote the utilization of wild and farm germplasm resources in the future; advance the research on the genes related to disease resistance,stress resistance and quality of grapes and cherries; push forward the construction and development of cherry and grape mutants banks. It is conducive to the research on the agronomic traits of grapes and cherries,and can provide the parents resources for planting innovation and improving the quality of grapes and cherries,as well as promote the development and application of molecular markers of grapes and cherries,including the identification of lines and crossbreeding. Thereby,it cannot only promote the industry development,but also achieve the development of cultivation,breeding and basic research in an all-round way and the development of ＂ production,study and research＂ going side by side.

Genome-wide Identification and Analysis of DNA Methyltransferases in Grape

DNA methylation is an important epigenetic regulation mechanism, which is catalyzed by DNA methyltransferases. In this study, eight DNA methyltransferase genes were identified in grape genome to analyze the selective pressure, gene expression and codon usage bias. The results showed grape DNA methyltransferase MET subfamily underwent relatively strong purifying selection during evolution, while chromomethylase CMT subfamily underwent positive selection during evolution. Under different abiotic(heat, drought or cold) stresses, the expression level of many grape DNA methyltransferase genes changed significantly. The expression level of these genes might be related with cis-regulatory elements of their promoters. The results of codon usage bias analysis showed that synonymous codon bias existed in grape DNA methyltransferase gene family, which might be affected by mutation pressure. These results laid a solid foundation for in-depth study of DNA methyltransferases in grape.

Identification and Analysis of SSRs Derived from Protein-coding Genes in Grape

SSR(Simple Sequence Repeats), also known as microsatellites or STRs(short tandem repeats), are a type of PCRbased markers. So far, the version of grape genome has been updated constantly, but SSRs derived from protein-coding genes in grape have not yet been identified. In this study, 4 337 SSR-containing genes were found among 29 971 protein-coding genes in grape(Vitis vinifera L.), and 5 384 SSRs were found. There were 96 types of repeat motifs in SSRs derived from protein-coding genes in grape, and the most frequently occurring repeat motif was A/T. Among various repeat motifs in dinucleotide SSRs, the most frequently occurring repeat motif was AG/CT. Moreover, many genes exhibited codon usage bias, which was affected by the mutation pressure. GO annotation, KEGG annotation and domain analysis of these genes were performed.Several genes were found to be closely related to the synthesis and metabolism of secondary metabolites, synthesis of flavones or anthocyanins, development and morphology of plant organs, and tolerance to biotic or abiotic stresses, including transcription factors in MYB, Hsf, NBS and TPC families. This study laid a solid foundation for the development of SSR markers and research of QTLs controlling complex agronomic traits in grape.

Analysis of Wheat GBSS1 Promoter:Tissue Specificity and DNA Methylation

The cis-regulatory elements of promoters regulate temporal and spatial expression of genes. DNA inethylation, histone methylation and histone acetylation are the main types of epigenetic modifications, which play important roles in plant growth and development. DNA methylation could seilenco transposons, affect gene imprinting and gene expression. In this study, we found that granule bound starch synthase 1 （GBSSI） gene is expressed specifically in wheat endosperm rath- er than in the embryo. We also analyzed the cis-elements within this promoter region and found some seed-specific elements. In order to confirm the tissue specifici- ty, we cloned 4k bp sequences upstream of GBSS1 gene to link to vector with GUS and this construct was transferred to tobacco by Agrobacterium mediated transfor- marion. The results showed that wheat GBSS1 promoter mediated the seed-specific expression of GUS gene, hut not mediated expression in embryo. In addition, we found that GBSSI promoter is methylated in wheat embryo and de-methylated in wheat endosperm. Our study might provide the molecular basis for specific expres- sion of GBSSI gene.

Advances in the Role of DNA Methylation and miRNAs in Plant Defense

DNA methylation and miRNAs are two important epigenetic molecular mechmxisms in plants. RNA-directed DNA methylation （RdDM） pathway is con- sidered as the most important mechanism of DNA methylation. A microRNA （miRNA） is processed from a 70-90-nucleotide-long single-stranded RNA precursor that forms a hairpin structure by Dicer enzyme, which plays an important role in plant development, regulation of plant gene expression and silencing of trans- posons. In recent years, a large number of studies have confirmed that DNA methylation and miRNAs play an important role in disease resistance mechanisms of plants. In this paper, recent progress on the role of DNA methylation and miRNAs in plant defense was summarized, which provided reference for revealing the re- lationship between disease resistance factors and epigenctic mechanisms in plants.