Vacuole Formation in Wheat Starchy Endosperm

The formation of vacuoles in wheat (Triticum aestivum cv. Highbury) starchy endosperm cells was studied using electron microscopy. Some vacuoles were always present, even in the coenocytic cytoplasm. The first formed endosperm cells were highly vacuolated, but became filled with cytoplasm as they grew older. Various-sized pieces of cytoplasm were found in vacuoles of developing endosperm cells, probably as a result of autophagic sequestration. The membranes of the autographic vacuoles appeared to originate from the rough endoplasmic reticulum and from extensions of already-formed vacuoles. Autographic activity was confirmed by localizing the hydrolytic enzyme acid phosphatase within the vacuoles. The rough endoplasmic reticulum (RER) also stained positive for this enzyme

USDA Plant Genome Research Program

The U.S. Congress appropriated funds in 1991 for the USDA Plant Genome Research Program, four years after its initial conception in 1987. The goal of the USDA Plant Genome Research Program is to improve plants (agronomic, horticultural, and forest tree species) by locating marker DNA or genes on chromosomes, determining gene structure, and transferring genes to improve plant performance with accompanying reduced environmental impact to meet marketplace needs and niches. The Plant Genome Research Program is one program with two parts: National Research Initiative and Plant Genome Database (PGD). The PGD is now a real and functioning information and data resource for agricultural and other plant science genome researchers, and it is in the public domain. Additional progress is given according to major plant groups. The PGD is a suite of several information products produced at the National Agricultural Library (NAL) in collaboration with the Agricultural Research Service and Forest Service species coordinators

Mapping of mitochondrial mRNA termini in Arabidopsis thaliana: t-elements contribute to 5′ and 3′ end formation

With CR–RT–PCR as primary approach we mapped the 5′ and 3′ transcript ends of all mitochondrial protein-coding genes in Arabidopsis thaliana. Almost all transcripts analyzed have single major 3′ termini, while multiple 5′ ends were found for several genes. Some of the identified 5′ ends map within promoter motifs suggesting these ends to be derived from transcription initiation while the majority of the 5' termini seems to be generated post-transcriptionally. Assignment of the extremities of 5′ leader RNAs revealed clear evidence for an endonucleolytic generation of the major cox1 and atp9 5′ mRNA ends. tRNA-like structures, so-called t-elements, are associated either with 5′ or with 3′ termini of several mRNAs. These secondary structures most likely act as cis-signals for endonucleolytic cleavages by RNase Z and/or RNase P. Since no conserved sequence motif is evident at post-transcriptionally derived ends, we suggest t-elements, stem–loops and probably complex higher order structures as cis-elements for processing. This analysis provides novel insights into 5′ and 3′ end formation of mRNAs. In addition, the complete transcript map is a substantial and important basis for future studies of gene expression in mitochondria of higher plants