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: Leaves of Sophora japonica produced the pterocarpanoid phytoalexins medicarpin and maackiain in response to inoculation with the fungus Helminthosporium carbonum and this appears to be the first case in which (+) enantiomers of 6aH pterOCarpans have been reported as phy toalexin samples.
41 citations
TL;DR: An inability by “P” strains to induce high levels of phytoalexins in cotton, not only makes them ineffective as biocontrol agents, but renders them pathogenic to susceptible cultivar seed lots.
41 citations
TL;DR: Two new prenylated stilbene dimers named arahypin-6 and arahYPin-7 have been isolated from wounded peanut seeds challenged by an Aspergillus caelatus strain and may play a defensive role against invasive fungi.
Abstract: The peanut plant can resist fungal attacks by producing stilbene-derived phytoalexins. Once understood, such a natural phytoalexin-based mechanism of peanut resistance could be potentially manipulated to obtain fungal-resistant peanut breeding lines. Several simple stilbenoid phytoalexins from peanuts have been reported. However, more complex stilbenoid derivatives such as those that have been reported from other sources and considered important factors in plant defense have not been found in peanuts. The purpose of this research was to isolate and characterize further new oligomeric peanut stilbenoids that may act as phytoalexins. Two new prenylated stilbene dimers named arahypin-6 (3) and arahypin-7 (4) have been isolated from wounded peanut seeds challenged by an Aspergillus caelatus strain. The structures of these new putative phytoalexins were determined by analysis of NMR, MS, and UV spectroscopic data. Together with other known peanut stilbenoids that were also produced in the challenged seeds, these new compounds may play a defensive role against invasive fungi.
41 citations
TL;DR: Investigation of the production and excretion of the coumarins scopoletin, its 7-O-glucoside scopolin, and ayapin in whole sunflower plants and isolated organs confirmed that their synthesis must be induced, being tissue-dependent and developmentally regulated.
40 citations
TL;DR: Capsidiol, a phytoalexin accumulated in Nicotiana attenuata in response to Alternaria alternata attack, plays an important role in pathogen resistance, and its biosynthesis is transcriptionally regulated by an ERF2-like transcription factor.
Abstract: Capsidiol is a sesquiterpenoid phytoalexin produced in Nicotiana and Capsicum species in response to pathogen attack. Whether capsidiol plays a defensive role and how its biosynthesis is regulated in the wild tobacco Nicotiana attenuata when the plant is attacked by Alternaria alternata (tobacco pathotype), a notorious necrotrophic fungus causing brown spot disease, are unknown. Transcriptome analysis indicated that a metabolic switch to sesquiterpene biosynthesis occurred in young leaves of N. attenuata after A. alternata inoculation: many genes leading to sesquiterpene production were strongly up-regulated, including the capsidiol biosynthetic genes 5-epi-aristolochene synthase (EAS) and 5-epi-aristolochene hydroxylase (EAH). Consistently, the level of capsidiol was increased dramatically in young leaves after fungal inoculation, from not detectable in mock control to 50.68±3.10 µg g-1 fresh leaf at 3 d post-inoculation. Capsidiol-reduced or capsidiol-depleted plants, which were generated by silencing EAHs or EASs by virus-induced gene silencing, were more susceptible to the fungus. In addition, this sesquiterpene when purified from infected plants exhibited strong anti-fungal activities against A. alternata in vitro. Furthermore, an ERF2-like transcription factor was found to positively regulate capsidiol production and plant resistance through the direct transactivation of a capsidiol biosynthetic gene, EAS12. Taken together, our results demonstrate that capsidiol, a phytoalexin highly accumulated in N. attenuata plants in response to A. alternata infection, plays an important role in pathogen resistance independent of jasmonate and ethylene signaling pathways, and its biosynthesis is transcriptionally regulated by an ERF2-like transcription factor.
40 citations