The SQUAMOSA-promoter binding like (SPL) gene family encodes transcription factors that have been shown in many species to influence plant growth and development, but information about these genes in barley (Hordeum vulgare L.) is limited. This study identified 17 barley SPL genes, within eight distinct groups, that are orthologs of SPL genes described in Arabidopsis, wheat, and rice. Sixteen barley SPLs undergo alternative splicing. Seven SPLs contain a putative miR156 target site and the transcript levels of the miR156-targeted HvSPLs (HvSPL3, 13 and 23) were lower in vegetative than in reproductive phase but this was true also for some SPL genes such as HvSPL6 that were not regulated by miR156. Because SPL gene products regulate miR172, which is also involved in floral development, the expression of miR172 was studied. An antagonistic expression pattern of miR156 and miR172b during the vegetative and the reproductive phases signifies their apparent function in barley growth phase transition. Characterization of a barley mir172 mutant having an abnormal, indeterminate spikelet phenotype suggests the possible feedback role of AP2/miR172 module on HvSPL genes. This is the first comprehensive analysis of the miR156/SPL/miR172 axis in barley that provides a basis to elucidate their roles in various biological processes.

Significance: The process of malting in the making of beer is under fine biological regulation. Here, we report the dissection of a malting quality quantitative trait locus (QTL) known for its association with variation in the yield of β-glucan and malt extract. A key gene, HvTLP8 , has been identified in the QTL2 region that is expressed differentially in barley malt and feed varieties, based on analyses of both mRNA and protein. The present finding that the affinity of recombinant HvTLP8 for insoluble barley β-glucan is redox-dependent suggests a key role for redox in the malting process. This discovery represents a significant step forward in understanding the biochemistry of malting.

Hemicelluloses are a diverse group of complex, non-cellulosic polysaccharides, which constitute approximately one-third of the plant cell wall and find use as dietary fibres, food additives and raw materials for biofuels. Genes involved in hemicellulose synthesis have not been extensively studied in small grain cereals. In efforts to isolate the sequences for the cellulose synthase-like (Csl) gene family from wheat, we identified 108 genes (hereafter referred to as TaCsl). Each gene was represented by two to three homeoalleles, which are named as TaCslXY_ZA, TaCslXY_ZB, or TaCslXY_ZD, where X denotes the Csl subfamily, Y the gene number and Z the wheat chromosome where it is located. A quarter of these genes were predicted to have 2 to 3 splice variants, resulting in a total of 137 putative translated products. Approximately 45% of TaCsl genes were located on chromosomes 2 and 3. Sequences from the subfamilies C and D were interspersed between the dicots and grasses but those from subfamily A clustered within each group of plants. Proximity of the dicot-specific subfamilies B and G, to the grass-specific subfamilies H and J, respectively, points to their common origin. In silico expression analysis in different tissues revealed that most of the genes were expressed ubiquitously and some were tissue-specific. More than half of the genes had introns in phase 0, one-third in phase 2, and a few in phase 1. Detailed characterization of the wheat Csl genes has enhanced the understanding of their structural, functional, and evolutionary features. This information will be helpful in designing experiments for genetic manipulation of hemicellulose synthesis with the goal of developing improved cultivars for biofuel production and increased tolerance against various stresses.

Cellulose is the primary determinant of mechanical strength in plant tissues. Late-season lodging is inversely related to the amount of cellulose in a unit length of the stem. Wheat is the most widely grown of all the crops globally, yet information on its CesA gene family is limited. We have identified 22 CesA genes from bread wheat, which include homoeologs from each of the three genomes, and named them as TaCesAXA, TaCesAXB or TaCesAXD, where X denotes the gene number and the last suffix stands for the respective genome. Sequence analyses of the CESA proteins from wheat and their orthologs from barley, maize, rice, and several dicot species (Arabidopsis, beet, cotton, poplar, potato, rose gum and soybean) revealed motifs unique to monocots (Poales) or dicots. Novel structural motifs CQIC and SVICEXWFA were identified, which distinguished the CESAs involved in the formation of primary and secondary cell wall (PCW and SCW) in all the species. We also identified several new motifs specific to monocots or dicots. The conserved motifs identified in this study possibly play functional roles specific to PCW or SCW formation. The new insights from this study advance our knowledge about the structure, function and evolution of the CesA family in plants in general and wheat in particular. This information will be useful in improving culm strength to reduce lodging or alter wall composition to improve biofuel production.