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.
Papers published on a yearly basis
Papers
More filters
TL;DR: It is concluded that Gα mediates the stimulation of PLA2 by low elicitor concentrations and that the resulting peak of LPC initiates a transient efflux of vacuolar protons, generating an acidic peak of the cytoplasmic pH that causes the expression of enzymes of phytoalexin production independent of the hypersensitive response.
Abstract: The function of a Galpha protein in the elicitation of phytoalexin (benzophenanthridine) biosynthesis was characterized in cultured cells of California poppy (Eschscholzia californica). Both the decrease of Galpha content via antisense transformation and the expression of recombinant anti-Galpha single-chain antibodies strongly impaired the induction of alkaloid biosynthesis by low elicitor concentrations. All transgenic cell types were deficient in two elicitor-triggered early signal events: activation of phospholipase A2 (PLA2) and efflux of vacuolar protons. The lacking H+ efflux could be restored (1) by adding lysophosphatidylcholine (LPC), a product of PLA2 activity, to vacuoles in situ and (2) by exposing intact cells to isotonic, near-neutral HEPES buffers. The latter treatment induced alkaloid biosynthesis in the absence of elicitor and in Galpha-deficient cells. We conclude that Galpha mediates the stimulation of PLA2 by low elicitor concentrations and that the resulting peak of LPC initiates a transient efflux of vacuolar protons. In this way, an acidic peak of the cytoplasmic pH is generated that causes the expression of enzymes of phytoalexin production independent of the hypersensitive response.
47 citations
TL;DR: In the incompatible interaction between soybean and the oomycete Phytophthora megasperma f.sp.
Abstract: Inducible plant defenses against potential pathogens are thought to be activated by signal compounds released during early stages of the infection process. In the incompatible interaction between soybean (Glycine max L.) and the oomycete Phytophthora megasperma f.sp. glycinea (= Phytophthora sojae) a rapid, localized phytoalexin response is activated at the level of transcription. The phytoalexin response is also stimulated in various soybean tissues, including cultured cells, following treatment with an elicitor derived from the cell walls of the fungus. The best characterized elicitors of P. megasperma for soybean are the branched (1→3)- and (1→6)-linked β-glucans, structural polysaccharides of the hyphal walls. The glucans are naturally released during the early stages of germination of the fungal cysts in a host-independent manner. Cyclic β-glucans of Bradyrhizobium japonicum USDA 110, a symbiont of soybean, arc not active in inducing phytoalexin production in soybean. When tested in combination, B. j...
47 citations
TL;DR: Identification of loci controlling maackiain metabolism (Mak genes) were identified by crosses among isolates of N. haematococca MP VI that differed in their ability to metabolize the phytoalexin.
Abstract: Some isolates of the plant-pathogenic fungus Nectria haematococca mating population (MP) VI metabolize maackiain and medicarpin, two antimicrobial compounds (phytoalexins) synthesized by chickpea (Cicer arietinum L.). The enzymatic modifications by the fungus convert the phytoalexins to less toxic derivatives, and this detoxification has been proposed to be important for pathogenesis on chickpea. In the present study, loci controlling maackiain metabolism (Mak genes) were identified by crosses among isolates of N. haematococca MP VI that differed in their ability to metabolize the phytoalexin. Strains carrying Mak1 or Mak2 converted maackiain to 1a-hydroxymaackiain, while those with Mak3 converted it to 6a-hydroxymaackiain. Mak1 and Mak2 were unusual in that they often failed to be inherited by progeny. Mak1 was closely linked to Pda6, a new member in a family of genes in N. haematococca MP VI that encode enzymes for detoxification of pisatin, the phytoalexin synthesized by garden pea. Like Mak1, Pda6 was also transmitted irregularly to progeny. Although the unusual meiotic behaviors of some Mak genes complicate genetic analysis, identification of these genes should afford a more through evaluation of the role of phytoalexin detoxification in the pathogenesis of N. haematococca MP VI on chickpea.
47 citations
TL;DR: In this article, a sesquiterpenoid phytoalexin, cichoralesin, was isolated from Cichorium intybus inoculated with Pseudomonas cichorexin and its structure was elucidated by spectroscopic methods.
47 citations
TL;DR: It was demonstrated that a small amount of Cerato-platanin elicited the synthesis of phytoalexins such as umbelliferone and glyceollin, in host plane leaves and non-host soybean cotyledons, respectively.
Abstract: SUMMARY Cerato-platanin (CP), a previously purified and sequenced protein of about 12.4 kDa, has been studied with regard to the relationship between the fungal growth and the in vitro production by Ceratocystis fimbriata f.sp. platani, the causal agent of plane canker stain. Obtaining CP-specific polyclonal antibodies from rabbit allowed us to prepare a quantitative ELISA which indicated that CP was produced by C. fimbriata f.sp. platani in the first days of in vitro culture. Moreover, for the first time it was demonstrated that a small amount (<2 nmol) of CP elicited the synthesis of phytoalexins such as umbelliferone and glyceollin, in host plane leaves and non-host soybean cotyledons, respectively.
47 citations