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Roulard, R.

Publications and source records attributed to Roulard, R..

2 recordsLinked to original sources
bioRxiv2024

Oligogalacturonides, produced by enzymatic degradation of sugar beet by-products, confer partial protection against wheat powdery mildew

Nowadays, it becomes urgent to use new alternative strategies for a more sustainable agriculture, by developing eco-friendly biocontrol compounds leading to an induction of plant resistance against pathogens. In recent years, oligogalacturonides (OGs), fragments of pectin resulting from the degradation of the plant cell wall, have been particularly under focus for their ability to induce plant defense, leading to plant protection against pathogens. In the current work, 2 mixtures of OGs, bio-sourced from sugar beet by-products, were produced and assessed for their protective efficacy on wheat against Blumeria graminis f. sp. tritici (Bgt), responsible for powdery mildew. These OGs pools were obtained by hydrolysing pectins with two A. thaliana polygalacturonases (PGs), ADPG2 and PGLR (EC 3.2.1.15), produced in heterologous system Pichia pastoris. No direct effect of OGs generated by either ADPG2, named OGs-ADPG2 (degree of polymerisation/DP 1-10 and degree of esterification/DE 41%) or PGLR, named OGs-PGLR (DP 1-16, DE 34 %), was observed on Bgt spore germination in vitro. After a preventive foliar spraying of wheat by OGs, only OGs-PGLR provided a 31 % partial protection against Bgt. Both pools of OGs triggered an increase in the expression of some plant defense-related genes (peroxidase or PR proteins encoding genes), before inoculation with the pathogen. However, only OGs-PGLR induced the expression of a gene encoding a lipoxygenase (LOX), which is the first enzyme involved in the octadecanoic pathway, leading to oxylipins production in plant defense. Taking together, these findings revealed that some OGs, produced from sugar beet by-products by enzymatic hydrolysis, could be used as an alternative of phytochemicals.

plant biology↗
bioRxiv2021

INTEGUMENT-SPECIFIC TRANSCRIPTIONAL REGULATION IN THE MID- STAGE OF FLAX SEED DEVELOPMENT INFLUENCES THE RELEASE OF MUCILAGE AND THE SEED OIL CONTENT

Flax (Linum usitatissimum L.) seed oil, which accumulates in the embryo, and mucilage, which is synthesized in the seed coat, are of great economic importance for food, pharmaceutical as well as chemical industries. Theories on the link between oil and mucilage production in seeds consist in the spatio-temporal competition of both compounds for photosynthates during the very early stages of seed development. In this study, we demonstrate a positive relationship between seed oil production and seed coat mucilage extrusion in the agronomic model, flax. Three recombinant inbred lines were selected for low, medium and high mucilage and seed oil contents. Metabolite and transcript profiling (1H NMR and DNA oligo-microarrays) was performed on the seeds during seed development. These analyses showed main changes in the seed coat transcriptome during the mid-phase of seed development (25 Days Post-Anthesis), once the mucilage biosynthesis and modification processes are thought to be finished. These transcriptome changes comprised genes that are putatively involved in mucilage chemical modification and oil synthesis, as well as gibberellic acid (GA) metabolism. The results of these integrative biology approach, suggest that transcriptional regulations of seed oil and fatty acid (FA) metabolism could occur in the seed coat during the mid-stage of seed development, once the seed coat carbon supplies have been used for mucilage biosynthesis and mechanochemical properties of the mucilage secretory cells.

plant biology↗