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: In this article, the authors demonstrate a causal relationship between early and late reactions of parsley cells to the elicitor and indicate a sequence of signaling events from receptor-mediated activation of ion channels via ROS production and defense gene activation to phytoalexin synthesis.
Abstract: Fungal elicitor stimulates a multicomponent defense response in cultured parsley cells (Petroselinum crispum). Early elements of this receptor-mediated response are ion fluxes across the plasma membrane and the production of reactive oxygen species (ROS), sequentially followed by defense gene activation and phytoalexin accumulation. Omission of Ca2+ from the culture medium or inhibition of elicitor-stimulated ion fluxes by ion channel blockers prevented the latter three reactions, all of which were triggered in the absence of elicitor by amphotericin B-induced ion fluxes. Inhibition of elicitor-stimulated ROS production using diphenylene iodonium blocked defense gene activation and phytoalexin accumulation. O2− but not H2O2 stimulated phytoalexin accumulation, without inducing proton fluxes. These results demonstrate a causal relationship between early and late reactions of parsley cells to the elicitor and indicate a sequence of signaling events from receptor-mediated activation of ion channels via ROS production and defense gene activation to phytoalexin synthesis. Within this sequence, O2− rather than H2O2 appears to trigger the subsequent reactions.
558 citations
TL;DR: Evidence in support of phytoalexins in resistance as well some recent advances in phy toalexin biosynthesis are reviewed and criteria for evaluating a role for phy ToALxin in disease resistance are discussed.
Abstract: One of the best and longest-studied defense response of plants to infection is the induced accumulation of antimicrobial, low-molecular-weight secondary metabolites known as phytoalexins. Since the phytoalexin hypothesis was first proposed in 1940, a role for these compounds in defense has been revealed through several experimental approaches. Support has come, for example, through studies on the rate of phytoalexins in relation to cessation of pathogen development, quantification of phytoalexins at the infection site, and relationship of pathogen virulence to the phytoalexin tolerance. Evidence in support of phytoalexins in resistance as well some recent advances in phytoalexin biosynthesis are reviewed. Criteria for evaluating a role for phytoalexins in disease resistance are also discussed.
558 citations
TL;DR: Proteins encoded by jasmonate-induced genes include enzymes of alkaloid and phytoalexin synthesis, storage proteins, cell wall constituents and stress protectants, and the wound-induced formation of proteinase inhibitors is a well-studied example.
535 citations
01 Jan 1997
TL;DR: A causal relationship between early and late reactions of parsley cells to the elicitor is demonstrated and a sequence of signaling events from receptor-mediated activation of ion channels via ROS production and defense gene activation to phytoalexin synthesis is indicated.
Abstract: Fungal elicitor stimulates am ulticomponent defense response in cultured parsley cells (Petroselinum crispum). Early elements of this receptor-mediated response are ion fluxes across the plasma membrane and the produc- tionofreactiveoxygenspecies(ROS),sequentiallyfollowedby defense gene activation and phytoalexin accumulation. Omis- sion of Ca 21 from the culture medium or inhibition of elicitor-stimulated ion fluxes by ion channel blockers pre- vented the latter three reactions, all of which were triggered in the absence of elicitor by amphotericin B-induced ion fluxes.Inhibitionofelicitor-stimulatedROSproductionusing diphenylene iodonium blocked defense gene activation and phytoalexin accumulation. O2 but not H2O2stimulated phy- toalexin accumulation, without inducing proton fluxes. These results demonstrate a causal relationship between early and late reactions of parsley cells to the elicitor and indicate a sequence of signaling events from receptor-mediated activa- tion of ion channels via ROS production and defense gene activation to phytoalexin synthesis. Within this sequence, O2 ratherthanH2O2appearstotriggerthesubsequentreactions.
513 citations
TL;DR: Infection of pad mutant plants with strains carrying cloned avirulence genes revealed that the pad mutations did not affect the plants' ability to restrict the growth of these strains, suggesting that in A. thaliana, phytoalexin biosynthesis is not required for resistance to avirulent P. syringae pathogens.
Abstract: A genetic approach was used to assess the extent to which a particular plant defense response, phytoalexin biosynthesis, contributes to Arabidopsis thaliana resistance to Pseudomonas syringae pathogens. The A. thaliana phytoalexin, camalexin, accumulated in response to infection by various P. syringae strains. No correlation between pathogen avirulence and camalexin accumulation was observed. A biochemical screen was used to isolate three mutants of A. thaliana ecotype Columbia that were phytoalexin deficient (pad mutants). The mutations pad1, pad2, and pad3 were found to be recessive alleles of three different genes. pad1 and pad2 were mapped to chromosome IV and pad3 was mapped to chromosome III. Infection of pad mutant plants with strains carrying cloned avirulence genes revealed that the pad mutations did not affect the plants' ability to restrict the growth of these strains. This result strongly suggests that in A. thaliana, phytoalexin biosynthesis is not required for resistance to avirulent P. syringae pathogens. Two of the pad mutants displayed enhanced sensitivity to isogenic virulent P. syringae pathogens, suggesting that camalexin may serve to limit the growth of virulent bacteria.
466 citations