Wild bees (Apoidea, Anthophila) of south-west France: more than 10 years of inventories in mosaic landscapes of "Vallées et Coteaux de Gascogne" (ZA-PYGAR).

Background: The reported massive decline of arthropods and particularly of pollinators such as wild bees, in terms of abundance and richness, is a threat for crop production and wild plant biodiversity conservation. This decline is mainly explained by a combination of drivers at local- and landscape-scale related to intensive farming practices. Assessing the evolution of wild bee communities in agricultural ecosystems and their response to such practices is needed to address conservation purposes.

The sunflower downy mildew pathogen Plasmopara halstedii.

Unlabelled: Downy mildew of sunflower is caused by Plasmopara halstedii (Farlow) Berlese & de Toni. Plasmopara halstedii is an obligate biotrophic oomycete pathogen that attacks annual Helianthus species and cultivated sunflower, Helianthus annuus. Depending on the sunflower developmental stage at which infection occurs, the characteristic symptoms range from young seedling death, plant dwarfing, leaf bleaching and sporulation to the production of infertile flowers.

Characterization of a cinnamoyl-CoA reductase 1 (CCR1) mutant in maize: effects on lignification, fibre development, and global gene expression.

Cinnamoyl-CoA reductase (CCR), which catalyses the first committed step of the lignin-specific branch of monolignol biosynthesis, has been extensively characterized in dicot species, but few data are available in monocots. By screening a Mu insertional mutant collection in maize, a mutant in the CCR1 gene was isolated named Zmccr1(-). In this mutant, CCR1 gene expression is reduced to 31% of the residual wild-type level.

Expression of cell wall related genes in basal and ear internodes of silking brown-midrib-3, caffeic acid O-methyltransferase (COMT) down-regulated, and normal maize plants.

Background: Silage maize is a major forage and energy resource for cattle feeding, and several studies have shown that lignin content and structure are the determining factors in forage maize feeding value. In maize, four natural brown-midrib mutants have modified lignin content, lignin structure and cell wall digestibility. The greatest lignin reduction and the highest cell wall digestibility were observed in the brown-midrib-3 (bm3) mutant, which is disrupted in the caffeic acid O-methyltransferase (COMT) gene.

Differential expression of phenylpropanoid and related genes in brown-midrib bm1, bm2, bm3, and bm4 young near-isogenic maize plants.

The expression of phenylpropanoid and related genes was investigated in bm1, bm2, bm3, and bm4 near-isogenic maize plants at the 4-5 leaf stage using a gene-specific cell wall macro-array. The bm3 mutant, which is mutated in the caffeic acid O-methyltransferase (COMT) gene, exhibited the lowest number of differentially expressed genes. Although no other phenylpropanoid gene had an altered expression, two distinct OMT and two cytochrome P450 genes were overexpressed suggesting the activation of alternative hydroxylation/methylation pathways.

MAIZEWALL. Database and developmental gene expression profiling of cell wall biosynthesis and assembly in maize.

An extensive search for maize (Zea mays) genes involved in cell wall biosynthesis and assembly has been performed and 735 sequences have been centralized in a database, MAIZEWALL (http://www.polebio.scsv.

Novel markers of xylogenesis in zinnia are differentially regulated by auxin and cytokinin.

The characterization of in vitro xylogenic cultures of zinnia (Zinnia elegans) has led to major discoveries in the understanding of xylem formation in plants. We have constructed and characterized a subtractive library from zinnia cultures enriched in genes that are specifically expressed at the onset of secondary wall deposition and tracheary element (TE) programmed cell death. This Late Xylogenesis Library (LXL) consisted of 236 nonredundant cDNAs, 77% of which encoded novel sequences in comparison with the 17,622 expressed sequence tag sequences publicly available.

hca: an Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning.

By screening a T-DNA population of Arabidopsis mutants for alterations in inflorescence stem vasculature, we have isolated a mutant with a dramatic increase in vascular tissue development, characterized by a continuous ring of xylem/phloem. This phenotype is the consequence of premature and numerous cambial cell divisions in both the fascicular and interfascicular regions that result in the loss of the alternate vascular bundle/fiber organization typically observed in Arabidopsis stems. The mutant was therefore designated high cambial activity (hca).

Down-regulation of caffeic acid o-methyltransferase in maize revisited using a transgenic approach.

Transgenic maize (Zea mays) plants were generated with a construct harboring a maize caffeic acid O-methyltransferase (COMT) cDNA in the antisense (AS) orientation under the control of the maize Adh1 (alcohol dehydrogenase) promoter. Adh1-driven beta-glucuronidase expression was localized in vascular tissues and lignifying sclerenchyma, indicating its suitability in transgenic experiments aimed at modifying lignin content and composition. One line of AS plants, COMT-AS, displayed a significant reduction in COMT activity (15%-30% residual activity) and barely detectable amounts of COMT protein as determined by western-blot analysis.