Organization of the photosynthetic apparatus from triazine resistant and susceptible biotypes of several plant species

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L'acide alpha linoléique présente un grand intérêt nutritionnel et pharmaceutique. Comment se forme-t-il dans la bourrache ?

L'acide alpha linoléique présente un grand intérêt nutritionnel et pharmaceutique. Comment se forme-t-il dans la bourrache ? . Journées de la Recherch

Biosynthesis of γ-linolenic acid in developing seeds of borgae (Borago officinalis L.)

Δ6-desaturation of [14C]linoleoyl-CoA or [14C]oleoyl-CoA leading to the synthesis of γ-linolenic acid was studied in vitro with microsomal fractions from developing seeds of Borago officinalis. Time course of the reaction, effects of protein and precursor concentrations and nucleotide requirements were examined. These parameters allowed us to improve the in vitro Δ6-desaturation assay. We observed that the precursors were acylated mainly in phophatidylcholine, dyacylglycerol and triacylglycerol, and then desaturated. NADH was absolutely required when [14C]oleoyl-CoA was the percursonr, but not when [14C]lionleoyl-CoA was the precursor although it stimulated the reaction. The in vitro Δ6-desaturate activity was found mainly in phosphatidylcholine, associated with enriched endoplasmic reticulum membranes (ER) from embryos. No activity was observed in ER from seed coat or seedling. During maturation of the seeds, Δ6-desaturase reached its highest activity 14 to 16 days after pollination

Application of cDNA array for studying the gene expression profile of mature appressoria of Magnaporthe grisea

Appressorium is an infection structure of the phytopathogenic fungus Magnaporthe grisea. Analysis of gene expression profiles of appressorium development provides insight into the molecular basis of pathogenicity and control of this fungal plant disease. A cDNA array representing 2927 unique genes based on a large EST (expressed sequence tag) database of M. grisea strain Y34 was constructed and used to profile the gene expression patterns at mycelium and appressorium maturation stages. Compared with mycelia, 55 up-regulated and 22 down-regulated genes were identified in mature appressoria. Among 77 genes, 16 genes showed no similarity to the genome sequences of M. grisea. A novel homologue of peptidyl-prolyl cis-trans isomerase was found to be expressed at low-level in mature appressoria of M. grisea. The results indicated that the genes such as pyruvate carboxylase, phospholipid metabolism-related protein and glyceraldehyde 3-phosphate dehydrogenase involved in gluconeogenesis, lipid metabolism and glycolysis, showed differential expression in mature appressoria. Furthermore, genes such as PTH11, beta subunit of G protein and SGT1 involved in cell signalling, were expressed differentially in mature appressoria. Northern blot analysis was used to confirm the cDNA array results