Analysis of barley (Hordeum vulgare) grain development using three-dimensional digital models.

Analysis of gene expression in the developing barley caryopsis requires effective instruments for visualization of the grain and the 3D expression patterns. Digital models of developing barley (Hordeum vulgare) grains were reconstructed from serial sections to visualize the complex three-dimensional (3D) grain anatomy, to generate and analyse 3D expression patterns, and to quantify tissues during growth. The models provide detailed spatial descriptions of developing grains at anthesis, at the syncytial stage of endosperm development and at the onset of starch accumulation, visualizing and quantifying 18 tissues or tissue complexes.

Transcript profiles and deduced changes of metabolic pathways in maternal and filial tissues of developing barley grains.

Different aspects of barley grain development have been studied in detail, but a more global analysis of gene expression patterns is still missing. We have employed macro arrays, containing 1184 unique sequences from 1421 barley cDNA fragments, to study gene expression profiles in maternal and filial tissues of developing barley caryopses from fertilization to early storage phase. Principle component analysis (PCA) defined distinct expression networks in the pre-storage (0, 2, and 4 days after flowering (DAF)) and early storage phase (10 and 12 DAF).

The role of invertases and hexose transporters in controlling sugar ratios in maternal and filial tissues of barley caryopses during early development.

To analyse carbohydrate metabolism and its role during early seed development of barley we characterised genes encoding two cell wall-bound invertases (HvCWINV1 and HvCWINV2) and two putative hexose transporter-like genes (HvSTP1 and HvSTP2). No typical vacuolar invertase gene could be identified. Instead, a gene encoding sucrose:fructan 6-fructosyltransferase (HvSF6FT1), an enzyme with soluble acid invertase activity, was isolated and characterised.

Antisense-inhibition of ADP-glucose pyrophosphorylase in developing seeds of Vicia narbonensis moderately decreases starch but increases protein content and affects seed maturation.

The small subunit of a Vicia faba ADP-glucose pyrophosphorylase (AGP) cDNA was expressed in antisense orientation in Vicia narbonensis under the control of the seed-specific legumin B4 promoter. From several independent transgenic lines both ADP-glucose pyrophosphorylase AGP-mRNA and AGP enzyme activity were reduced by up to 95% in the cotyledons during the mid- to late-maturation phase. Starch was moderately decreased and sucrose was increased.

Sugar levels altered by ectopic expression of a yeast-derived invertase affect cellular differentiation of developing cotyledons of Vicia narbonensis L.

In order to change the sugar status during seed development a yeast-derived invertase gene was expressed in cotyledons of Vicia narbonensis. As a result, sucrose decreased whereas hexoses accumulated. We analysed cell structure and cellular differentiation in cotyledons expressing the yeast-invertase.