Structure and expression of phosphoglucan phosphatase genes of Like Sex Four1 and Like Sex Four2 in barley

Genes That Mediate Starch Metabolism in Developing and Germinated Barley Grain

Starch is synthesized in the endosperm of developing barley grain, where it functions as the primary source of stored carbohydrate. In germinated grain these starch reserves are hydrolyzed to small oligosaccharides and glucose, which are transported to the embryo to support the growth of the developing seedling. Some of the mobilized glucose is transiently stored as starch in the scutellum of germinated grain. These processes are crucial for early seedling vigor, which is a key determinant of crop productivity and global food security. Several starch synthases (SS), starch-branching enzymes (SBEs), and starch debranching enzymes (isoamylases, ISA), together with a limit dextrinase (LD), have been implicated in starch synthesis from nucleotide-sugar precursors. Starch synthesis occurs both in the developing endosperm and in the scutellum of germinated grain. For the complete depolymerization of starch to glucose, α-amylase (Amy), β-amylase (Bmy), isoamylase (ISA), limit dextrinase (LD), and α-glucosidase (AGL) are required. Most of these enzymes are encoded by gene families of up to 10 or more members. Here RNA-seq transcription data from isolated tissues of intact developing and germinated barley grain have allowed us to identify the most important, specific gene family members for each of these processes in vivo and, at the same time, we have defined in detail the spatio-temporal coordination of gene expression in different tissues of the grain. A transcript dataset for 81,280 genes is publicly available as a resource for investigations into other cellular and biochemical processes that occur in the developing grain from 6 days after pollination.

Molecular characterization of the TaWTG1 in bread wheat (Triticum aestivum L.)

OsWTG1 (LOC_Os08g42540.1) functions as an important factor determining grain size and shape in rice. Our understanding on its ortholog in wheat, TaWTG1, is limited. Here, we identified and mapped TaWTG1 in wheat, characterized its gene and protein structures, predicted transcription factor binding sites of its promoter, and the expression patterns was also analysed bases on real-time quantitative PCR and public available microarray data. The WTG1 orthologs in barley (HvWTG1), rice (OsWTG1), Aegilops tauschii (AtWTG1), Triticum urartu (TuWTG1), Triticum turgidum (TtWTG1) and Brachypodium distachyon (BdWTG1) were also identified for comparative analyses. TaWTG1 was mapped onto the short arms of group 7 chromosomes (7AS, 7BS, and 7DS). Multiple alignments indicated that WTG1 possesses eight exons and seven introns in all of the orthologs, except for the orthologs on 7A of wild emmer and on 7D of A. tauschii (seven exons and six introns). An exon-intron junction composed of intron 2 to intron 3 and exon 2 to exon 4 was highly conserved. The protein of WTG1 exists a conserved domain (Peptidase_C65). WTG1 was mainly expressed in wheat roots, spikes and grains, in barley caryopsis and roots, and in rice anthers. Drought and heat stresses significantly regulated the expression of TaWTG1 in wheat. In barley, WTG1 was significantly down-regulated under Fusarium at late stage. In addition, significant correlations between the expression patterns of predicted transcription factors and WTG1 were also detected. Overall, the results presented here broaden our knowledge on WTG1 and will be helpful for its manipulation aiming at dissecting its function in plants.