Showing papers on "Phytoalexin published in 1973"
TL;DR: The use of virus-infected tissue as a source of new phytoalexins, the role of these compounds in disease resistance and their possible importance in explaining virus-induced resistance to fungal pathogens are discussed.
Abstract: Etiolated bean hypocotyls underwent necrosis and cellular browning following infection by tobacco necrosis virus. This was accompanied by the production of many phenolic compounds, some of which were shown to be highly antifungal in assays of fungal growth on thin-layer plates. Four compounds, phaseollin, phaseollidin, phaseollinisoflavan and kievitone, were isolated and identified. Their minimum lethal doses towards spore germination of Colletotrichum lindemuthianum were 2, 2, 2 and 20 μg/ml respectively. In addition, following their isolation in high yield from virus-infected tissue, they were also demonstrated in tissue infected with C. lindemuthianum. They have thus been referred to as phytoalexins. The use of virus-infected tissue as a source of new phytoalexins, the role of these compounds in disease resistance and their possible importance in explaining virus-induced resistance to fungal pathogens are discussed.
127 citations
67 citations
TL;DR: The alfalfa pathogen was shown to alter, and possibly degrade, two phytoalexins, pisatin and phaseollin, found in non-host plants, and their first conversion products were detected in pod diffusates and in infected tissues from detached leaves.
Abstract: The alfalfa pathogen, Stemphylium botryosum , was shown to alter, and possibly degrade, two phytoalexins, pisatin and phaseollin, found in non-host plants. In vitro rates of breakdown depended on phytoalexin concentration and size of inoculum; maximum rates were, however, much lower than those reported for medicarpin, the phytoalexin from alfalfa. Mycelial growth in bioassays was initially inhibited by more than 10 μg/ml of either non-host phytoalexin, but ED 50 values increased markedly during incubation. The first conversion product formed from pisatin or phaseollin was as inhibitory to fungal growth as the parent phytoalexin but each was itself broken down during further incubation of mycelial cultures. The phytoalexins and their first conversion products were detected in pod diffusates and in infected tissues from detached leaves. However, assuming a localized distribution around each infection site, enough pisatin or phaseollin was present to account, theoretically, for the observed cessation of fungal growth.
30 citations
TL;DR: Evidence that ability to metabolize phytoalexin may be an important characteristic of some phytopathogenic fungi is provided, suggesting that phy toaleXin metabolism takes place within fungal hyphae.
Abstract: The phytoalexin wyerone acid appeared to be metabolized by Botrytis fabae at a faster rate than by B. cinerea in vitro. Loss of wyerone acid caused by B. fabae, but not B. cinerea, was associated with the appearance of a novel u.v. absorbing substance (substance I). Substance I was purified by paper chromatography and found to behave as an ether soluble acid. The concentration of substance I in B. fabae infection droplets incubated in pod seed cavities increased rapidly between 1 and 3 days after inoculation. Substance I from B. fabae pod diffusate was purified by repeated t.l.c. and methylated to facilitate spectroscopic analyses. The metabolite was identified as reduced wyerone acid, and was much less antifungal to B. cinerea and B. fabae than wyerone acid. Substance I could not be detected in healthy tissues or large lesions caused by B. cinerea in broad bean leaves, but increased at B. fabae inoculation sites as tissues became blackened and colonized by B. fabae. No extracellular enzymes capable of degrading wyerone acid could be detected in diffusates from pods infected with B. fabae, suggesting that phytoalexin metabolism takes place within fungal hyphae. This work provides evidence that ability to metabolize phytoalexin may be an important characteristic of some phytopathogenic fungi.
27 citations
21 citations
TL;DR: The isolation and identification of the major detoxification product of wyerone acid (a phytoalexin from Vicia faba L.), produced by Botrytis fabae, are described.
Abstract: The isolation and identification of the major detoxification product of wyerone acid (a phytoalexin fromVicia faba L.), produced byBotrytis fabae, are described. The compound has been shown to be 3-[5-(1-hydroxy-cis-hept-4-enyl)-2-furyl]-trans-prop-2-enoic acid, by total synthesis of the methyl ester.
10 citations
Journal Article•
4 citations