Deciphering the mechanisms involved in reduced sensitivity to azoles and fengycin lipopeptide in Venturia inaequalis.

Apple scab, caused by the hemibiotrophic fungus Venturia inaequalis, is currently the most common and damaging disease in apple orchards. Two strains of V. inaequalis (S755 and Rs552) with different sensitivities to azole fungicides and the bacterial metabolite fengycin were compared to determine the mechanisms responsible for these differences.

Deciphering immune responses primed by a bacterial lipopeptide in wheat towards .

Plant immunity induction with natural biocontrol compounds is a valuable and promising ecofriendly tool that fits with sustainable agriculture and healthy food. Despite the agroeconomic significance of wheat, the mechanisms underlying its induced defense responses remain obscure. We reveal here, using combined transcriptomic, metabolomic and cytologic approach, that the lipopeptide mycosubtilin from the beneficial bacterium , protects wheat against through a dual mode of action (direct and indirect) and that the indirect one relies mainly on the priming rather than on the elicitation of plant defense-related mechanisms.

Bioinspired Rhamnolipid Protects Wheat Against Through Mainly Direct Antifungal Activity and Without Major Impact on Leaf Physiology.

Rhamnolipids (RLs), glycolipids biosynthesized by the and genera, are known to display various activities against a wide range of pathogens. Most previous studies on RLs focused on their direct antimicrobial activity, while only a few reports described the mechanisms by which RLs induce resistance against phytopathogens and the related fitness cost on plant physiology. Here, we combined transcriptomic and metabolomic approaches to unravel the mechanisms underlying RL-induced resistance in wheat against the hemibiotrophic fungus , a major pathogen of this crop.

Importance of the C Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against .

The hemibiotrophic fungus , responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat- pathosystem.

Mechanisms underlying iron deficiency-induced resistance against pathogens with different lifestyles.

Iron (Fe) is a poorly available mineral nutrient which affects the outcome of many cross-kingdom interactions. In Arabidopsis thaliana, Fe starvation limits infection by necrotrophic pathogens. Here, we report that Fe deficiency also reduces disease caused by the hemi-biotrophic bacterium Pseudomonas syringae and the biotrophic oomycete Hyaloperonospora arabidopsidis, indicating that Fe deficiency-induced resistance is effective against pathogens with different lifestyles.

Rhizobacteria-Mediated Activation of the Fe Deficiency Response in Arabidopsis Roots: Impact on Fe Status and Signaling.

The beneficial root-colonizing rhizobacterium WCS417 stimulates plant growth and induces systemic resistance against a broad spectrum of plant diseases. In (Arabidopsis), the root transcriptional response to WCS417 shows significant overlap with the root response to iron (Fe) starvation, including activation of the marker genes and . Here, we investigated how colonization of Arabidopsis roots by WCS417 impacts Fe homeostasis in roots and shoots.

Iron and Immunity.

Iron is an essential nutrient for most life on Earth because it functions as a crucial redox catalyst in many cellular processes. However, when present in excess iron can lead to the formation of harmful hydroxyl radicals. Hence, the cellular iron balance must be tightly controlled.

The Pseudomonas fluorescens Siderophore Pyoverdine Weakens Arabidopsis thaliana Defense in Favor of Growth in Iron-Deficient Conditions.

Pyoverdines are siderophores synthesized by fluorescent Pseudomonas spp. Under iron-limiting conditions, these high-affinity ferric iron chelators are excreted by bacteria in the soil to acquire iron. Pyoverdines produced by beneficial Pseudomonas spp.

β-Aminobutyric acid (BABA)-induced resistance in Arabidopsis thaliana: link with iron homeostasis.

β-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro.

NO signaling in plant immunity: a tale of messengers.

Nitric oxide (NO) is a free radical gas involved in a myriad of plant physiological processes including immune responses. How NO mediates its biological effects in plant facing microbial pathogen attack is an unresolved question. Insights into the molecular mechanisms by which it propagates signals reveal the contribution of this simple gas in complex signaling pathways shared with reactive oxygen species (ROS) and the second messenger Ca(2+).

There's more to the picture than meets the eye: nitric oxide cross talk with Ca2+ signaling.

Calcium and nitric oxide (NO) are two important biological messengers. Increasing evidence indicates that Ca(2+) and NO work together in mediating responses to pathogenic microorganisms and microbe-associated molecular patterns. Ca(2+) fluxes were recognized to account for NO production, whereas evidence gathered from a number of studies highlights that NO is one of the key messengers mediating Ca(2+) signaling.