Topic
Phytoalexin
About: Phytoalexin is a research topic. Over the lifetime, 1161 publications have been published within this topic receiving 63405 citations. The topic is also known as: phytoalexins.
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TL;DR: The accumulation of phaseollin appeared to be more closely associated with cell death than the accumulation of pisatin, which led to a loss of electrolytes during the initial 12 h, and to the continuous accumulation of phytoalexins over 5 days.
Abstract: Phaseollin and pisatin accumulated in bean and pea cotyledons respectively, after incubation at 25 °C following treatment with mercuric chloride. Both the duration of treatment and concentration of mercuric chloride determined maximal phytoalexin concentrations. Highest levels of both phytoalexins occurred when cell damage caused by mercuric chloride was microscopically visible. With increasing amounts of dead cells the concentrations of phytoalexins decreased, and in some treatments no phytoalexins were formed even when some tissue was still alive. The accumulation of phaseollin appeared to be more closely associated with cell death than the accumulation of pisatin. Treatment of cotyledons with mercuric chloride under optimal conditions for phytoalexin formation (10 −3 m for 30 min) led to a loss of electrolytes during the initial 12 h, and to the continuous accumulation of phytoalexins over 5 days. Exudates from mercuric chloride treated cotyledons of both species stimulated phytoalexin accumulation in cut cotyledon bioassays. These results are discussed in relation to current views on the mechanism of phytoalexin accumulation.
55 citations
TL;DR: Study of degradation of pterostilbene that has just one free hydroxy phenyl group function allowed us to determine the oxidative dimerization process undergone by grapevine phytoalexins after B. cinerea infection.
Abstract: In the interaction between grapevines and Botrytis cinerea, one of the main aspects of pathogenicity is fungal ability to degrade phytoalexins synthesized by the plant in response to infection. Laccase-like stilbene oxidase activity in liquid cultures of B. cinerea has been shown to be related to the decrease of phytoalexin concentrations. Recent research and results presented in this paper determined the chemical structure of a pterostilbene metabolite produced by B. cinerea. Study of degradation of pterostilbene that has just one free hydroxy phenyl group function allowed us to determine the oxidative dimerization process undergone by grapevine phytoalexins after B. cinerea infection. The phytopathological significance of this degradation process in the B. cinerea interaction has also been discussed.
55 citations
TL;DR: Three new phytoalexins, named isalexin (9), brassicanate A (10), and rutalex in (11) were isolated and their biological activity against four plant pathogens were determined.
Abstract: Phytoalexins are inducible chemical defenses produced de novo by plants in response to diverse forms of stress, including microbial attack. Our search for phytoalexins from economically important crucifers lead us to examine rutabaga tubers (Brassica napus L. ssp. rapifera). Three new phytoalexins, named isalexin (9), brassicanate A (10), and rutalexin (11), were isolated together with five known phytoalexins, brassinin (4), 1-methoxybrassinin (5), spirobrassinin (13), brassicanal A (14), and brassilexin (15). The chemical structures of the new phytoalexins were proven by syntheses, and their biological activity against four plant pathogens were determined. Biosynthetic studies using tetra- and pentadeuterated precursors established that indolyl-3-acetaldoxime (22) and brassinin (4) are precursors of brassicanate A (10) and rutalexin (11) and that cyclobrassinin (23) is a biosynthetic precursor of rutalexin (11), whereas tryptamine (24) is not a precursor of rutabaga phytoalexins.
55 citations
TL;DR: PG-II and PG-IV released heat-stable elicitors from purified soybean cell walls supporting the evidence that uronides are intermediate inducers in elicitation by endo-PGs.
55 citations
TL;DR: It is suggested that strain BTP1 can elicit systemic phytoalexin accumulation in tomato as one defence mechanism and key enzymes of the lipoxygenase pathway are stimulated in plants treated with the bacteria as compared with control plants.
Abstract: Previous studies showed the ability of Pseudomonas putida strain BTP1 to promote induced systemic resistance (ISR) in different host plants. Since ISR is long-lasting and not conducive for development of resistance of the targeted pathogen, this phenomenon can take part of disease control strategies. However, in spite of the numerous examples of ISR induced by PGPR in plants, only a few biochemical studies have associated the protective effect with specific host metabolic changes. In this study, we showed the protective effect of this bacterium in tomato against Botrytis cinerea. Following treatment by P. putida BTP1, analyses of acid-hydrolyzed leaf extracts showed an accumulation of antifungal material after pathogen infection. The fungitoxic compounds thus mainly accumulate as conjugates from which active aglycones may be liberated through the activity of hydrolytic enzymes. These results suggest that strain BTP1 can elicit systemic phytoalexin accumulation in tomato as one defence mechanism. On another hand, we have shown that key enzymes of the lipoxygenase pathway are stimulated in plants treated with the bacteria as compared with control plants. Interestingly, this stimulation is observed only after pathogen challenge in agreement with the priming concept almost invariably associated with the ISR phenomenon. Through the demonstration of phytoalexin accumulation and LOX pathway stimulation in tomato, this work provides new insights into the diversity of defence mechanisms that are inducible by non-pathogenic bacteria in the context of ISR.
55 citations