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.

The Cysteine2/Histidine2-Type Transcription Factor ZINC FINGER OF ARABIDOPSIS THALIANA6 Modulates Biotic and Abiotic Stress Responses by Activating Salicylic Acid-Related Genes and C-REPEAT-BINDING FACTOR Genes in Arabidopsis

Abstract: The cysteine2/histidine2-type zinc finger proteins are a large family of transcription regulators, and some of them play essential roles in plant responses to biotic and abiotic stress. In this study, we found that expression of C2H2-type ZINC FINGER OF ARABIDOPSIS THALIANA6 (AtZAT6) was transcriptionally induced by salt, dehydration, cold stress treatments, and pathogen infection, and AtZAT6 was predominantly located in the nucleus. AtZAT6-overexpressing plants exhibited improved resistance to pathogen infection, salt, drought, and freezing stresses, while AtZAT6 knockdown plants showed decreased stress resistance. AtZAT6 positively modulates expression levels of stress-related genes by directly binding to the TACAAT motifs in the promoter region of pathogen-related genes (ENHANCED DISEASE SUSCEPTIBILITY1, PHYTOALEXIN DEFICIENT4, PATHOGENESIS-RELATED GENE1 [PR1], PR2, and PR5) and abiotic stress-responsive genes (C-REPEAT-BINDING FACTOR1 [CBF1], CBF2, and CBF3). Moreover, overexpression of AtZAT6 exhibited pleiotrophic phenotypes with curly leaves and small-sized plant at vegetative stage and reduced size of floral organs and siliques at the reproductive stage. Modulation of AtZAT6 also positively regulates the accumulation of salicylic acid and reactive oxygen species (hydrogen peroxide and superoxide radical). Taken together, our findings indicated that AtZAT6 plays important roles in plant development and positively modulates biotic and abiotic stress resistance by activating the expression levels of salicylic acid-related genes and CBF genes.

Phytoalexin production by hypocotyls of Phaseolus vulgaris in response to constitutive metabolites released by damaged bean cells

Abstract: Phaseollin and phaseollidin were the predominant phytoalexins formed when live and dead bean hypocotyl tissues were incubated in contact with each other. The phytoalexins were produced by the live cells which were in close association with the dead tissue and were then taken up and accumulated in the dead cells. Small amounts of phytoalexins were produced when live tissues were incubated together, but none were formed when dead tissue was incubated alone. Aqueous extracts of bean tissue stimulated phytoalexin formation, suggesting that when bean cells were damaged, e.g. by freezing or maceration, a water-soluble component capable of eliciting phytoalexin formation was released. The active component was insoluble in organic solvents, was heat stable and passed through a dialysis membrane. Phaseollin and phaseollidin levels decreased in solutions which contained live tissue, dead tissue or isolated hypocotyl cell walls. Both phytoalexins were easily extracted from dead tissue or cell wall material but very little could be recovered from live tissue. The results indicate that bean cells contain a constitutive component capable of eliciting phytoalexin production. This possibility, along with the accumulation of phytoalexins by dead cells and their metabolism by living cells, is discussed in relation to the accumulation of these phytoalexins which occurs in response to infection by Colletotrichum lindemuthianum and in response to other external stimuli.