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.

Studies on the incompatible and compatible interactions between lucerne leaves and Verticillium albo-atrum

Abstract: Phytoalexin production and host cell death in lucerne ( Medicago sativa ) leaves were investigated following inoculation with either a virulent or an avirulent isolate of Verticillum albo-atrum . Attempted penetration in the incompatible interaction leads to rapid host cell death and to the rapid accumulation of medicarpin and sativan. High concentrations of both these phytoalexins were maintained throughout the incubation period and hyphal growth on the leaf surface was restricted. In the compatible interaction, only low levels of phytoalexins were produced over the first few days but the virulent isolate was not restricted and colonization of the leaf tissue continued. Later, even when high levels of medicarpin and sativan were produced in association with gross tissue damage, the progress of the pathogen was not halted.

The Significance of Stilbene-Type Phytoalexin Degradation by Culture Filtrates of Botrytis Cinerea in the Vine- Botrytis Interaction

Abstract: Phytoalexins, antimicrobial compounds, synthesized by a plant in response to infection or a variety of stresses are known to be the most efficient way by which grapevines withstand an attack by Botrytis cinerea Pers, the causal organism for grey mould In that plant, such responses include the production of a simple stilbene, resveratrol, and the biosynthetically related compounds, viniferins and pterostilbene If stilbene-type phytoalexins represent a contributory factor in the resistance of grapevines to Bcinerea, the capacity of the pathogen to metabolize antifungal compounds released by the host could also play a significant role in the outcome of the interaction between grapevines and BcinereaIndeed, the net accumulation of phytoalexins within plant tissues infected by various pathogens is probably controlled by a balance which may result, on the one hand, from the ability of the host cells to resist colonization by creating an inhibitory barrier for the parasite, and, on the other hand, from tolerance of the pathogen to antifungal compounds produced by the plant and from its ability to detoxify the phytoalexins to which it is exposed Thus, the resistance of plants to infection depends on the phytoalexin production/degradation balance following attack by the pathogen A variety of factors can alter this balance in favour of either the parasite or the host, resulting in non-compatible or compatible interactions Among these, the capacity of Bcinerea to detoxify the phytoalexins produced by grapevines was investigated We present here good evidence that this fungus produces a stilbene oxidase which can degrade resveratrol and pterostilbene No detoxication of stilbenes is detected during the germination process in vitro, suggesting that stilbene-degrading activity does not seem to be constitutive in dormant conidia of Botrytis