The genetic diversity of group-1 homoeologs and characterization of novel LMW-GS genes from Chinese Xinjiang winter wheat landraces (Triticum aestivum L.)

Transcriptome and Proteome Analysis Revealed the Influence of High-Molecular-Weight Glutenin Subunits (HMW-GSs) Deficiency on Expression of Storage Substances and the Potential Regulatory Mechanism of HMW-GSs

The processing quality of wheat is affected by seed storage substances, such as protein and starch. High-molecular-weight glutenin subunits (HMW-GSs) are the major components of wheat seed storage proteins (SSPs); they are also key determinators of wheat end-use quality. However, the effects of HMW-GSs absence on the expression of other storage substances and the regulation mechanism of HMW-GSs are still limited. Previously, a wheat transgenic line LH-11 with complete deletions of HMW-GSs was obtained through introducing an exogenous gene Glu-1E^bx to the wild-type cultivar Bobwhite by transgenic approach. In this study, comparative seed transcriptomics and proteomics of transgenic and non-transgenic lines at different seed developmental stages were carried out to explore the changes in genes and proteins and the underlying regulatory mechanism. Results revealed that a number of genes, including genes related to SSPs, carbohydrates metabolism, amino acids metabolism, transcription, translation, and protein process were differentially enriched. Seed storage proteins displayed differential expression patterns between the transgenic and non-transgenic line, a major rise in the expression levels of gliadins were observed at 21 and 28 days post anthesis (DPA) in the transgenic line. Changes in expressions of low-molecular-weight glutenins (LMW-GSs), avenin-like proteins (ALPs), lipid transfer proteins (LTPs), and protease inhibitors (PIs) were also observed. In addition, genes related to carbohydrate metabolism were differentially expressed, which probably leads to a difference in starch component and deposition. A list of gene categories participating in the accumulation of SSPs was proposed according to the transcriptome and proteome data. Six genes from the MYB and eight genes from the NAC transcription families are likely important regulators of HMW-GSs accumulation. This study will provide data support for understanding the regulatory network of wheat storage substances. The screened candidate genes can lay a foundation for further research on the regulation mechanism of HMW-GSs.

Characterization of novel LMW-i genes with nine cysteine residues from Chinese wheat landraces (Triticum aestivum L.) and analysis of their functional properties on dough mixing

The low-molecular-weight glutenin subunits (LMW-GS) with extra cysteine numbers have attracted great research interest for their potential quality value. In this study, 14 LMW-i type genes (YD1-YD14) were isolated from three types of Chinese wheat landraces; and nine of 14 genes (YD1-YD9) had nine cysteines, and the other five genes contained eight cysteines. Phylogenic analysis suggested that all 14 LMW-i genes were related to Glu-A3-1 variants Glu-A3-17/FJ 549934 and Glu-A3-15/FJ 549932. Six randomly selected genes, five genes including YD 1 with nine cysteines and the remaining one with eight cysteines, were successfully expressed in bacteria as mature proteins with a molecular mass of ~ 46 kDa. These proteins were traced to corresponding seed storage proteins for having similar elution times in reverse phase high-performance liquid chromatography (RP-HPLC) profiles. Mass spectrometry verified that bacterial expressed protein pET-30a-YD1 was LMW-i. Dough mixing experiments for incorporation of 50 mg pET-30a-YD1 proteins into the base flour of weak gluten wheat cv. "Chuannong 16" indicated that the dough strength of mixing flours was noticeably weaker than that of the control, which was reflected by mixing parameters in 8-min curve width, peak width, peak height, mixing time, and right of peak slope. The results suggested that the LMW-i genes with nine cysteine residues in the present study contributed to inferior quality properties for wheat flour.

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The online version contains supplementary material available at 10.1007/s13205-021-03044-8.