PGPR-Soil Microbial Communities' Interactions and Their Influence on Wheat Growth Promotion and Resistance Induction against Mycosphaerella graminicola.

The efficiency of plant-growth-promoting rhizobacteria (PGPR) may not be consistently maintained under field conditions due to the influence of soil microbial communities. The present study aims to investigate their impact on three PGPR-based biofertilizers in wheat. We used the PGPR Paenibacillus sp. strain B2 (PB2), PB2 in co-inoculation with Arthrobacter agilis 4042 (Mix 2), or with Arthrobacter sp. SSM-004 and Microbacterium sp. SSM-001 (Mix 3). Inoculation of PB2, Mix 2, and Mix 3 into non-sterile field soil had a positive effect on root and aboveground dry biomass, depending on the wheat cultivar. The efficiency of the PGPR was further confirmed by the protection they provided against Mycosphaerella graminicola, the causal agent of Septoria leaf blotch disease. PB2 exhibited protection of ≥37.8%, while Mix 2 showed ≥47.9% protection in the four cultivars tested. These results suggest that the interactions between PGPR and native soil microbial communities are crucial for promoting wheat growth and protection. Additionally, high-throughput sequencing of microbial communities conducted 7 days after PGPR inoculations revealed no negative effects of PB2, Mix 2, and Mix 3 on the soil microbial community structure. Interestingly, the presence of Arthrobacter spp. appeared to mitigate the potential negative effect of PB2 on bacterial community and foster root colonization by other beneficial bacterial strains.

Formulated hydroxy fatty acids from fruit pomaces reduce apple scab development caused by Venturia inaequalis through a dual mode of action.

The outermost hydrophobic layer of plants, i.e. the cuticle, is mainly composed of cutin, a polyester of hydroxy fatty acids with reported eliciting and/or antimicrobial activities for some of them. By-products of the fruit processing industry (fruit pomaces), often strongly enriched in cuticular material, are therefore a potential source of bioactive compounds for crop protection against pathogen attack. We investigated the utilization of tomato and apple pomaces in the development of a cutin-based biocontrol solution against apple scab, a major apple disease caused by Venturia inaequalis. Several cutin monomer extracts obtained through different strategies of depolymerization and purification were first compared for their ability to induce a targeted set of defense genes in apple seedlings after foliar application. After a step of formulation, some extracts were chosen for further investigation in planta and in vitro. Our results show that formulated cutin monomers could trigger a significant transcriptome reprogramming in apple plants and exhibit an antifungal effect on V. inaequalis. Cutin monomers-treated apple seedlings were significantly protected against infection by the apple scab agent. Altogether, our findings suggest that water-dispersed cutin monomers extracted from pomaces are potential new bio-based solutions for the control of apple scab.

Low catalyst loadings for the production of carboxylic acids from polysaccharides and hydrogen peroxide.

The oxidation of starch, xylans, potato flesh and wheat flour by H(2)O(2), in the presence of MSO(4) (M=Cu, Fe) as catalyst, led to depolymerization, and formation of solutions containing polyhydroxycarboxylic acids. Some of these oxidized compounds facilitate the process, leading to efficient transformations even with very low amounts of catalyst.

Photochemical key steps in the synthesis of surfactants from furfural-derived intermediates.

Furfural is oxidized to 2[5H]-furanone by using hydrogen peroxide or to 5-hydroxy-2[5H]-furanone by using photo-oxygenation. An amine function is introduced by photochemically induced radical addition of tertiairy amines, some of which carry an n-alkyl side chain as hydrophobic moiety. These amines are produced from fatty aldehydes and cyclic secondary amines. The resulting adducts are transformed into amphoteric surfactants possessing an ammonium and a carboxylate function. Amphoteric (pK(N) and isoelectric point) and surfactant properties such as the critical micelle concentration and the adsorption efficiency are determined.