ROLE OF NH4+ NUTRITION ON SALT-INDUCED OXIDATIVE STRESS IN CARRIZO CITRANGE PLANTS
Absence of endo-1,4-β-glucanase KOR1 alters the Jasmonate-dependent defence response to Pseudomonas syringae in Arabidopsis
During plant-pathogen interactions, the plant cell wall forms part of active defence against invaders. In recent years, cell wall-editing enzymes, associated with growth and development, have been related to plant susceptibility or resistance. Our previous work identified a role for several tomato and Arabidopsis endo-1,4-β-glucanases (EGs) in plant-pathogen interactions. Here we studied the response of the Arabidopsis thaliana T-DNA insertion mutant lacking EG Korrigan1 (KOR1) infected with Pseudomonas syringae. KOR1 is predicted to be an EG which is thought to participate in cellulose biosynthesis. We found that kor1-1 plants were more susceptible to P. syringae, and displayed severe dise…
Preventive and post-infection control ofBotrytis cinereain tomato plants by hexanoic acid
The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration- and pH-dependent manner, and stopped spore germination at a very early stage, preventing germ-tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 m m . Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 m m . Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of …
Priming of plant resistance by natural compounds. Hexanoic acid as a model
Some alternative control strategies of currently emerging plant diseases are based on the use of resistance inducers. This review highlights the recent advances made in the characterization of natural compounds that induce resistance by a priming mechanism. These include vitamins, chitosans, oligogalacturonides, volatile organic compounds, azelaic and pipecolic acid, among others. Overall, other than providing novel disease control strategies that meet environmental regulations, natural priming agents are valuable tools to help unravel the complex mechanisms underlying the induced resistance (IR) phenomenon. The data presented in this review reflect the novel contributions made from studyin…
Priming for JA-dependent defenses using hexanoic acid is an effective mechanism to protect Arabidopsis against B. cinerea
Abstract Soil drench treatments with hexanoic acid can effectively protect Arabidopsis plants against Botrytis cinerea through a mechanism based on a stronger and faster accumulation of JA-dependent defenses. Plants impaired in ethylene, salicylic acid, abscisic acid or glutathion pathways showed intact protection by hexanoic acid upon B. cinerea infection. Accordingly, no significant changes in the SA marker gene PR-1 in either the SA or ABA hormone balance were observed in the infected and treated plants. In contrast, the JA signaling pathway showed dramatic changes after hexanoic acid treatment, mainly when the pathogen was present. The impaired JA mutants, jin1-2 and jar1 , were unable …
Priming: getting ready for battle
International audience; Infection of plants by necrotizing pathogens or colonization of plant roots with certain beneficial microbes causes the induction of a unique physiological state called “priming.” The primed state can also be induced by treatment of plants with various natural and synthetic compounds. Primed plants display either faster, stronger, or both activation of the various cellular defense responses that are induced following attack by either pathogens or insects or in response to abiotic stress. Although the phenomenon has been known for decades, most progress in our understanding of priming has been made over the past few years. Here, we summarize the current knowledge of p…
Functional analysis of endo-1,4-β-glucanases in response to Botrytis cinerea and Pseudomonas syringae reveals their involvement in plant-pathogen interactions.
Plant cell wall modification is a critical component in stress responses. Endo-1,4-β-glucanases (EGs) take part in cell wall editing processes, e.g. elongation, ripening and abscission. Here we studied the infection response of Solanum lycopersicum and Arabidopsis thaliana with impaired EGs. Transgenic TomCel1 and TomCel2 tomato antisense plants challenged with Pseudomonas syringae showed higher susceptibility, callose priming and increased jasmonic acid pathway marker gene expression. These two EGs could be resistance factors and may act as negative regulators of callose deposition, probably by interfering with the defence-signalling network. A study of a set of Arabidopsis EG T-DNA insert…
A tolerant behavior in salt-sensitive tomato plants can be mimicked by chemical stimuli
Lycopersicon esculentum plants exhibit increased salt stress tolerance following treat‑ ment with adipic acid monoethylester and 1,3‑diaminepropane (DAAME), known as an inducer of resistance against biotic stress in tomato and pepper. For an efficient water and nutrient uptake, plants should adapt their water potential to compensate a decrease in water soil potential produced by salt stress. DAAME‑treated plants showed a faster and stronger water potential reduction and an enhanced proline accumulation. Salinity‑induced oxidative stress was also ameliorated by DAAME treatments. Oxidative membrane damage and ethylene emission were both reduced in DAAME‑treated plants. This effect is probably…
Combining Hexanoic Acid Plant Priming with Bacillus thuringiensis Insecticidal Activity against Colorado Potato Beetle
Interaction between insect herbivores and host plants can be modulated by endogenous and exogenous compounds present in the source of food and might be successfully exploited in Colorado potato beetle (CPB) pest management. Feeding tests with CPB larvae reared on three solanaceous plants (potato, eggplant and tomato) resulted in variable larval growth rates and differential susceptibility to Bacillus thuringiensis Cry3Aa toxin as a function of the host plant. An inverse correlation with toxicity was observed in Cry3Aa proteolytic patterns generated by CPB midgut brush-border membrane vesicles (BBMV) from Solanaceae-fed larvae, being the toxin most extensively proteolyzed on potato, followed…
An engineered plant that accumulates higher levels of heavy metals than Thlaspi caerulescens, with yields of 100 times more biomass in mine soils
8 pages, 3 figures, 2 tables.
Hexanoic Acid Treatment Prevents Systemic MNSV Movement in Cucumis melo Plants by Priming Callose Deposition Correlating SA and OPDA Accumulation
Unlike fungal and bacterial diseases, no direct method is available to control viral diseases. The use of resistance-inducing compounds can be an alternative strategy for plant viruses. Here we studied the basal response of melon to Melon necrotic spot virus (MNSV) and demonstrated the efficacy of hexanoic acid (Hx) priming, which prevents the virus from systemically spreading. We analysed callose deposition and the hormonal profile and gene expression at the whole plant level. This allowed us to determine hormonal homeostasis in the melon roots, cotyledons, hypocotyls, stems and leaves involved in basal and hexanoic acid-induced resistance (Hx-IR) to MNSV. Our data indicate important roles…
Hexanoic acid is a resistance inducer that protects tomato plants againstPseudomonas syringaeby priming the jasmonic acid and salicylic acid pathways
Summary Hexanoic acid-induced resistance (Hx-IR) is effective against several pathogens in tomato plants. Our study of the mechanisms implicated in Hx-IR against Pseudomonas syringae pv. tomato DC3000 suggests that hexanoic acid (Hx) treatment counteracts the negative effect of coronatine (COR) and jasmonyl-isoleucine (JA-Ile) on the salicylic acid (SA) pathway. In Hx-treated plants, an increase in the expression of jasmonic acid carboxyl methyltransferase (JMT) and the SA marker genes PR1 and PR5 indicates a boost in this signalling pathway at the expense of a decrease in JA-Ile. Moreover, Hx treatment potentiates 12-oxo-phytodienoic acid accumulation, which suggests that this molecule mig…
Three novel synthetic amides of adipic acid protect Capsicum anuum plants against the necrotrophic pathogen Alternaria solani
Three novel amides of adipic acid, 5-carbamoil ethyl pentanoate (N1), 5-(2-furfurylmethylcarbamoil) ethyl pentanoate (N2) and 5-(3-aminopropylcarbamoil) ethyl pentanoate (N3) were synthesized and their resistance-inducing activity was studied on pepper (Capsicum annuum) plants. Treatment with low doses of each amide protected pepper plants against the pathogen Alternaria solani, N1 being the most effective. Although their mode of action is still unknown, prechallenge studies demonstrated the induction of the phenylpropanoid pathway and an antisenescence effect. These effects were previously shown for other mixtures and derivatives of adipic acid. These new chemicals showed no antimicrobial …
Role of dioxygenase α-DOX2 and SA in basal response and in hexanoic acid-induced resistance of tomato (Solanum lycopersicum) plants against Botrytis cinerea.
Resistance of tomato (Solanum Lycopersicum) to the fungal pathogen Botrytis cinerea requires complex interplay between hormonal signalling. In this study, we explored the involvement of new oxylipins in the tomato basal and induced response to this necrotroph through the functional analysis of the tomato α-dioxygenase2 (α-DOX2)-deficient mutant divaricata. We also investigated the role of SA in the defence response against this necrotrophic fungus using SA-deficient tomato nahG plants. The plants lacking dioxigenase α-DOX2, which catalyses oxylipins production from fatty acids, were more susceptible to Botrytis, and hexanoic acid-induced resistance (Hx-IR) was impaired; hence α-DOX2 is requ…
Hexanoic acid protects tomato plants againstBotrytis cinereaby priming defence responses and reducing oxidative stress
Summary Treatment with the resistance priming inducer hexanoic acid (Hx) protects tomato plants from Botrytis cinerea by activating defence responses. To investigate the molecular mechanisms underlying hexanoic acid-induced resistance (Hx-IR), we compared the expression profiles of three different conditions: Botrytis-infected plants (Inf), Hx-treated plants (Hx) and Hx-treated + infected plants (Hx+Inf). The microarray analysis at 24 h post-inoculation showed that Hx and Hx+Inf plants exhibited the differential expression and priming of many Botrytis-induced genes. Interestingly, we found that the activation by Hx of other genes was not altered by the fungus at this time point. These genes…
An untargeted global metabolomic analysis reveals the biochemical changes underlying basal resistance and priming in Solanum lycopersicum, and identifies 1-methyltryptophan as a metabolite involved in plant responses to Botrytis cinerea and Pseudomonas syringae.
n this study, we have used untargeted global metabolomic analysis to determine and compare the chemi-cal nature of the metabolites altered during the infection of tomato plants (cv. Ailsa Craig) with Botry-tis cinerea (Bot)orPseudomonas syringae pv. tomato DC3000 (Pst), pathogens that have different invasionmechanisms and lifestyles. We also obtained the metabolome of tomato plants primed using the naturalresistance inducer hexanoic acid and then infected with these pathogens. By contrasting the metabolomicprofiles of infected, primed, and primed + infected plants, we determined not only the processes or compo-nents related directly to plant defense responses, but also inferred the metabolic…
Oxylipin mediated stress response of a miraculin-like protease inhibitor in Hexanoic acid primed eggplant plants infested by Colorado potato beetle
Insect-plant interactions are governed by a complex equilibrium between the mechanisms through which plant recognize insect attack and orchestrate downstream signaling events that trigger plant defense responses, and the mechanisms by which insects overcome plant defenses. Due to this tight and dynamic interplay, insight into the nature of the plant defense response can be gained by analyzing changes in the insect herbivores digestive system upon plant feeding. In this work we have identified a Solanum melongena miraculin-like protease inhibitor in the midgut juice of Colorado potato larvae feeding on eggplant plants treated with the natural inducer of plant defenses hexanoic acid. We analy…
Absence of the endo-beta-1,4-glucanases Cel1 and Cel2 reduces susceptibility to Botrytis cinerea in tomato.
Cel1 and Cel2 are members of the tomato (Solanum lycopersicum Mill) endo-beta-1,4-glucanase (EGase) family that may play a role in fruit ripening and organ abscission. This work demonstrates that Cel1 protein is present in other vegetative tissues and accumulates during leaf development. We recently reported the downregulation of both the Cel1 mRNA and protein upon fungal infection, suggesting the involvement of EGases in plant-pathogen interactions. This hypothesis was confirmed by assessing the resistance to Botrytis cinerea infection of transgenic plants expressing both genes in an antisense orientation (Anti-Cel1, Anti-Cel2 and Anti-Cel1-Cel2). The Anti-Cel1-Cel2 plants showed enhanced …