Deposition Of Storage Products Research Articles

Probing the endosperm gene expression landscape in Brassica napus

BackgroundIn species with exalbuminous seeds, the endosperm is eventually consumed and its space occupied by the embryo during seed development. However, the main constituent of the early developing seed is the liquid endosperm, and a significant portion of the carbon resources for the ensuing stages of seed development arrive at the embryo through the endosperm. In contrast to the extensive study of species with persistent endosperm, little is known about the global gene expression pattern in the endosperm of exalbuminous seed species such as crucifer oilseeds.ResultsWe took a multiparallel approach that combines ESTs, protein profiling and microarray analyses to look into the gene expression landscape in the endosperm of the oilseed crop Brassica napus. An EST collection of over 30,000 entries allowed us to detect close to 10,000 unisequences expressed in the endosperm. A protein profile analysis of more than 800 proteins corroborated several signature pathways uncovered by abundant ESTs. Using microarray analyses, we identified genes that are differentially or highly expressed across all developmental stages. These complementary analyses provided insight on several prominent metabolic pathways in the endosperm. We also discovered that a transcription factor LEAFY COTYLEDON (LEC1) was highly expressed in the endosperm and that the regulatory cascade downstream of LEC1 operates in the endosperm.ConclusionThe endosperm EST collection and the microarray dataset provide a basic genomic resource for dissecting metabolic and developmental events important for oilseed improvement. Our findings on the featured metabolic processes and the LEC1 regulatory cascade offer new angles for investigation on the integration of endosperm gene expression with embryo development and storage product deposition in seed development.

Alterations of the glutathione redox state improve apical meristem structure and somatic embryo quality in white spruce (Picea glauca)

In white spruce, an improvement of somatic embryo number and quality can be achieved through experimental manipulations of the endogenous levels of reduced (GSH) and oxidized (GSSG) glutathione. An optimal protocol for embryo production included an initial application of GSH in the maturation medium, followed by replacement with GSSG during the remaining maturation period. Under these conditions, the overall embryo population more than doubled, and the percentage of fully developed embryos increased from 22% to almost 70%. These embryos showed improved post-embryonic growth and conversion frequency. Structural studies revealed remarkable differences between embryo types, especially in storage product deposition pattern and organization of the shoot apical meristem (SAM). Compared with their control counterparts, glutathione-treated embryos accumulated a larger amount of starch during the early stages of development, and more protein and lipid bodies during the second half of development. Differences were also noted in the organization of SAMs. Shoot meristems of control embryos were poorly organized and were characterized by the presence of intercellular spaces, which caused separation of the subapical cells. Glutathione-treated embryos had well-organized meristems composed of tightly packed cells which lack large vacuoles. The improved organization of the shoot apical meristems in treated embryos was ascribed to a lower production of ethylene. Differences in meristem structure between control and treated embryos were also related to the localization pattern of HBK1, a shoot apical meristem 'molecular marker' gene with preferential expression to the meristematic cells of the shoot pole. Expression of this gene, which was localized to the apical cells in control embryos, was extended to the subapical cells of treated embryos. Overall, it appears that meristem integrity and embryo quality are under the direct control of the glutathione redox state.

Lipid Composition of in vitro Developing Seeds of Brassica campestris L.

A liquid culture technique has been developed to study lipid metabolism in seeds of Brassica campestris L. grown in vitro from terminal inflorescences detached 4 to 46 days after anthesis. Seeds developed under these conditions exhibited pattern of growth, deposition of storage products and lipid composition similar to those from intact plant.

Seasonal trends in river biofilm storage products and electron transport system activity

SUMMARY. 1. Glycogen, poly‐beta‐hydroxyalkanoate (PHA) and electron transport system (ETS) activity levels were monitored seasonally in light‐ and dark‐grown biofilms from a North Wales river.2. A spring peak was evident in glycogen, PHA and ETS activity levels per cm2 and per cell, with the exception of PHA per cell, which peaked in the winter.3. There was a seasonal shift in the type of storage product found, perhaps reflecting seasonal changes in carbon sources.4. The light‐grown spring biofilm yielded the greatest amount of bio‐film storage products per cm2. This should be taken into account during caloric studies of river biofilms as a food source for grazing invertebrates.5. A model is presented of factors influencing storage product deposition in river biofilms. The thickness and cell packing of river biofilms should be noted in future studies. Storage product deposition can occur deep within thick biofilms, irrespective of the river water chemistry.

Seed development in peas: knowing your three ‘r's’ (or four, or five)

AbstractThe value of the garden pea (Pisum sativum) both as an experimental tool and food crop has led to an accumulated wealth of genetic variation. This paper describes how some of the variation may be harnessed for studying seed development. One can identify genotypic differences for maternal, embryonic and cellular components and the interaction between them. The impact of these components on processes such as cell division, partitioning and the deposition of storage products can then be assessed by utilizing new techniques such as immunocytochemistry andin situhybridization.Therugosusloci, which induce wrinkling of the seed, are examples of how major genes can be exploited to dissect seed development. Alleles at one of these loci,r, have been defined at both the molecular and biochemical levels. A much clearer picture can now be drawn of the pleiotropic nature of the genes, from their effects on starch composition to those on cellular development, which has implications for seed development in many species. Therugosusloci are the only ones known to affect seed development in peas. By analogy with cereal seeds, however, one would anticipate other mutants in the starch pathway which also affect the shape of the seed. Here, we report the induction of newrugosus-like mutants, compare them to starch mutants in other species and examine the ways in which they may help our understanding of starch biosynthesis and the regulation of seed development.

Seasonal changes in the ultrastructure of cambium ofFagus sylvatica L.

Cells of the resting vascular cambium ofFagus sylvatica contain vesiculate smooth endoplasmic reticulum, free ribosomes, oil droplets, protein bodies and few or no vacuoles. Active cambial cells and young differentiating xylem elements are highly vacuolate and contain rough cisternal ER and polyribosomes. The Golgi apparatus is active in the production of vesicles and particles of about 25 nm diameter are found just outside the plasmalemma of differentiating xylem cells. The possibility that vacuoles are formed by the progressive dissolution of stored proteins during the onset of cambial activity, and that protein bodies are formed by deposition of storage products in vacuoles, is confirmed.