Biology subjects

Brisset, M.-N.

Publications and source records attributed to Brisset, M.-N..

4 recordsLinked to original sources

bioRxiv2025

Welcome pathogens: transient heat dampens the responses to acibenzolar-S-methyl beyond defenses in apple plants

Climate change affects plant-pathogen interactions, with disease outcome varying depending on pathosystem and environmental scenario. In Arabidopsis, a thermo-sensitive module of salicylic acid (SA) signaling makes immunity vulnerable to heat. The potent resistance inducer acibenzolar-S-methyl (ASM), an SA analogue that up-regulates transcription of defense genes, could restore plant protection under heat but not core SA signaling. Here, we investigated how high temperature rewires the ASM-induced responses of the apple immune system. We treated apple plants with ASM under contrasting heatwave scenarios and subsequently exposed them to Erwinia amylovora (the fire blight bacterium) or Venturia inaequalis (the apple scab fungus) while monitoring gene expression. While pre-exposing apple plants to high temperature did not change their susceptibility to pathogens, it drove a loss of ASM-induced protection. Transcriptomic analysis revealed broad dampening of ASM-regulation upon high temperature, for a wide range of biological processes beyond defense. We uncovered thermo-sensitive "resistance" and "susceptibility" marker genes with ASM-responsiveness being critically vulnerable to heat. We concluded that exposure to heatwave prevents ASM from fully mounting its protective responses in apple, not only lowering defenses but also offering more favorable hosting conditions. Our work highlights plant immunity as the joint outcome of resistant and susceptible responses. Summary StatementWe found that heatwaves "disarm" apples ability to mount an effective inducible-immunity response against two major diseases, fire blight and apple scab. Heatwaves not only prevent full expression of plant defenses, but also favor a physiological status that is beneficial to the pathogens.

plant biology↗

bioRxiv2024

Dual NBT Approach: Gene Editing and Intragenesis to promote Fire Blight Resistance in Apple using MdAGG defense lectins.

Fire blight, caused by the bacterium Erwinia amylovora, represents a significant threat to apple (Malus domestica) production. Currently, only a limited number of genes effectively involved in resistance to E. amylovora have been identified. Seeking new resistance candidates, we focused on a multigene family encoding amaranthin-like lectins, which are highly upregulated following chemical elicitation by acibenzolar-S-methyl (ASM). These lectins are believed to contribute to downstream defense by promoting bacterial aggregation, which led to their designation as M. domestica agglutinins (MdAGG). When loss-of-function editions were introduced into MdAGG genes, the plants ability to mount a fully effective defense response against fire blight upon ASM treatment was compromised, confirming the role of MdAGGs in fire blight resistance. Next, we coupled the pPPO16 promoter, endogenous to apple and known to be rapidly induced during E. amylovora infection, with the coding sequence of MdAGG10 to create apple lines with fire blight-inducible MdAGG10 expression. Early MdAGG10 expression in these lines significantly improved resistance to fire blight, and an additional ASM treatment further enhanced this resistance. In summary, we conclude that MdAGGs act as defense genes whose timely expression can provide effective resistance against E. amylovora.

plant biology↗

bioRxiv2023

Overexpression of an apple broad range agglutinating lectin does not promote in planta resistance to fire blight and bacterial wilt.

Lectins, a large group of proteins present in all kingdoms of life can bind reversibly to glycans. The roles of plant lectins are diverse and include resistance to biotic or abiotic stress, notably bacterial resistance. A gene family encoding amaranthin-like lectins termed MdAGGs in apple (Malus domestica) has been identified to be overexpressed upon treatment with the plant resistance inducer acibenzolar-S-methyl (ASM) which promotes enhanced resistance to the fire blight disease caused by Erwinia amylovora (Ea). In this study, we first screened the ability of purified MdAGG10 to agglutinate bacterial cells in vitro among a range of bacterial species. Several bacterial species, either Gram positive or negative, either plant- or human-pathogens were found to be agglutinated by MdAGG10 in acidic conditions. Apple and Arabidopsis lines constitutively overexpressing MdAGG10 were generated and evaluated for their resistance to, respectively, Ea and Ralstonia solanacearum, both plant pathogens that were found in our screening. Despite MdAGG10 protein accumulated in tissues of both apple and Arabidopsis lines, they remained susceptible to their respective pathogens. Interestingly, in vitro agglutination of Ea by MdAGG10 did not impair bacterial growth, suggesting that other plant molecules are involved in the resistance to fire blight triggered after an ASM treatment.

plant biology↗

bioRxiv2019

An Erwinia amylovora inducible promoter for intragenic improvement of apple fire blight resistance

Intragenesis is an important alternative to transgenesis to produce modified plants containing native DNA only. A key point to develop such a strategy is the availability of regulatory sequences controlling the expression of the gene of interest. With the aim of finding apple gene promoters either inducible by the fire blight pathogen Erwinia amylovora (Ea) or moderately constitutive, we focused on polyphenoloxidase genes (PPO). These genes encode oxidative enzymes involved in many physiological processes and have been previously shown to be up-regulated during the Ea infection process. We found ten PPO and two PPO-like sequences in the apple genome and characterized the promoters of MdPPO16 (pPPO16) and MdKFDV02 PPO-like (pKFDV02) for their potential as Ea-inducible and low-constitutive regulatory sequences respectively. Expression levels of reporter genes fused to these promoters and transiently or stably expressed in apple were quantified after various treatments. Unlike pKFDV02 which displayed a variable activity, pPPO16 allowed a fast and strong expression of transgenes in apple following Ea infection in a Type 3 Secretion System dependent manner. Altogether our results indicate that pKFDV02 did not keep its promises as a constitutive and weak promoter whereas pPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes. Key messagepPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes.

bioengineering↗