Cereal grasses of the Triticeae tribe have been the major food source in temperate regions since the dawn of agriculture. Their large genomes are characterized by a high content of repetitive elements and large pericentromeric regions that are virtually devoid of meiotic recombination. Here we present a high-quality reference genome assembly for barley (Hordeum vulgare L.). We use chromosome conformation capture mapping to derive the linear order of sequences across the pericentromeric space and to investigate the spatial organization of chromatin in the nucleus at megabase resolution. The composition of genes and repetitive elements differs between distal and proximal regions. Gene family analyses reveal lineage-specific duplications of genes involved in the transport of nutrients to developing seeds and the mobilization of carbohydrates in grains. We demonstrate the importance of the barley reference sequence for breeding by inspecting the genomic partitioning of sequence variation in modern elite germplasm, highlighting regions vulnerable to genetic erosion.

Legume seed development is characterized by progressive differentiation of organs and tissues resulting in developmental gradients A developmental gradient results from the gradual differentiation of different organs or within a single-seed organ and is reflected by heterogeneous populations of cells of different physiological age accumulating different amounts of substances, e.g., mRNAs, proteins, and starch. . The whole process is prone to metabolic control, and distinct metabolite profiles specify the differentiation state. Whereas early embryo growth is mainly maternally controlled, the transition into maturation implies a switch to filial control. A signaling network involving sugars, ABA abscisic acid , and SnRK1 kinases governs maturation. Processes of maturation are activated by changing oxygen/energy levels and/or a changing nutrient state, which trigger responses at the level of transcription and protein phosphorylation. This way seed metabolism becomes adapted to altering conditions. In maturing cotyledons photoheterotrophic metabolism Photoheterotrophic metabolism occurs in green seeds in which specific photoheterotrophic plastids import sugars, are photosynthetically active, and produce oxygen, thereby supporting respiration and overall metabolic activity. improves internal oxygen supply and biosynthetic fluxes and influences assimilate partitioning. Transgenic legumes with changed metabolic pathways and seed composition provide suitable models to study pathway regulation and metabolic control. At the same time, desirable improvements of seed quality and yield may be achieved.

The aquatic Lemnaceae family, commonly called duckweed, comprises some of the smallest and fastest growing angiosperms known on Earth. Their tiny size, rapid growth by clonal propagation, and facile uptake of labeled compounds from the media were attractive features that made them a well-known model for plant biology from 1950 to 1990. Interest in duckweed has steadily regained momentum over the past decade, driven in part by the growing need to identify alternative plants from traditional agricultural crops that can help tackle urgent societal challenges, such as climate change and rapid population expansion. Propelled by rapid advances in genomic technologies, recent studies with duckweed again highlight the potential of these small plants to enable discoveries in diverse fields from ecology to chronobiology. Building on established community resources, duckweed is reemerging as a platform to study plant processes at the systems level and to translate knowledge gained for field deployment to address some of society’s pressing needs. This review details the anatomy, development, physiology, and molecular characteristics of the Lemnaceae to introduce them to the broader plant research community. We highlight recent research enabled by Lemnaceae to demonstrate how these plants can be used for quantitative studies of complex processes and for revealing potentially novel strategies in plant defense and genome maintenance.

To analyze sugar transport processes during seed development of fava bean, we cloned cDNAs encoding one sucrose and one hexose transporter, designated VfSUT1 and VfSTP1, respectively. sugar uptake activity was confirmed after heterologous expression in yeast. Gene expression was studied in relation to seed development. Transcripts were detected in both vegetative and seed tissues. In the embryo, VfSUT1 and VfSTP1 mRNAs were detected only in epidermal cells, but in a different temporal and spatial pattern. VfSTP1 mRNA accumulates during the midcotyledon stage in epidermal cells covering the mitotically active parenchyma, whereas the VfSUT1 transcript was specific to outer epidermal cells showing transfer cell morphology and covering the storage parenchyma. Transfer cells developed at the contact area of the cotyledonary epidermis and the seed coat, starting first at the early cotyledon stage and subsequently spreading to the abaxial region at the late cotyledon stage. Feeding high concentrations of sugars suppressed both VfSUT1 expression and transfer cell differentiation in vitro, suggesting a control by carbohydrate availability.