| Popis: |
Phytoalexins are compounds which accumulate in plants following infection and various forms of stress. The term stress metabolites more accurately describes this diverse group of compounds since their accumulation after infection appears to be primarily a function of stress rather than of infection. Their relationship to stress, however, does not preclude their participation in mechanisms for disease resistance. Phytoalexins are produced by non-hosts as well as by resistant and susceptible cultivars of species. They accumulate in plants to concentrations that are inhibitory to the growth of infectious agents when tested in vitro. Phytoalexins have been characterized in the Leguminosae, Solanaceae, Malvaceae, Rosa-ceae, Convolvulaceae, Umbelliferae and Compositae. They have not been characterized in other families of major agronomic importance, e.g., Granrineae and Cucurbitacaceae. Since phytoalexins accumulate at and around sites of infection to levels inhibitory to the growth of infectious agents, their relationship to the containment of microbial development in plants cannot be ignored. Opinions differ as to the extent of their contribution in determining susceptibility or resistance. |
