Peroxidase-dependent apoplastic oxidative burst in Arabidopsis required for pathogen resistance.

The oxidative burst is an early response to pathogen attack leading to the production of reactive oxygen species (ROS) including hydrogen peroxide. Two major mechanisms involving either NADPH oxidases or peroxidases that may exist singly or in combination in different plant species have been proposed for the generation of ROS. We identified an Arabidopsis thaliana azide-sensitive but diphenylene iodonium-insensitive apoplastic oxidative burst that generates H(2)O(2) in response to a Fusarium oxysporum cell-wall preparation.

Production of reactive oxygen species in Arabidopsis thaliana cell suspension cultures in response to an elicitor from Fusarium oxysporum: implications for basal resistance.

The present understanding of ROS generation in the defence response of Arabidopsis thaliana is reviewed. Evidence suggests that the apoplastic oxidative burst generated during basal resistance is peroxidase-dependent. The ROS generated during this basal resistance may serve to activate NADPH oxidase during the R-gene-mediated hypersensitive response.

Characterisation and immunolocation of an 87 kDa polypeptide associated with UDP-glucuronic acid decarboxylase activity from differentiating tobacco cells (Nicotiana tabacum L.).

UDP-glucuronic acid decarboxylase catalyses the reaction responsible for the formation of UDP-xylose and commits assimilate for the biosynthesis of cell wall polysaccharides and glycosylation of proteins. Xylose-rich polymers such as xylans are a feature of dicot secondary walls. Thus a cell culture system of tobacco transformed with the ipt gene from Agrobacterium tumefaciens for cytokinin production and which when manipulated with auxin and sucrose leads to induction of xylogenesis, has been used as a source for purification of the enzyme.

Regulation of CDPKs, including identification of PAL kinase, in biotically stressed cells of French bean.

Changes in protein kinase activity have been investigated during the early response of suspension cultured cells of French bean to fungal elicitor. One of the kinases activated has a known target, phenylalanine ammonia-lyase (PAL), which has an important role in plant defence responses, and was purified. Kinase acivity during purification was monitored for both the PAL-derived peptide and syntide-2, which it also phosphorylated.

The apoplastic oxidative burst in response to biotic stress in plants: a three-component system.

The oxidative burst, the generation of reactive oxygen species (ROS) in response to microbial pathogen attack, is a ubiquitous early part of the resistance mechanisms of plant cells. It has also become apparent from the study of a number of plant-pathogen interactions and those modelled by elicitor treatment of cultured cells that there may be more than one mechanism operating. However, one mechanism may be dominant in any given species.

Early signalling events in the apoplastic oxidative burst in suspension cultured French bean cells involve cAMP and Ca.

•  Modulators of cAMP, calcium and G proteins were used to treat bean (Phaseolus vulgaris) cells before addition of an elicitor from Colletotrichum lindemuthianum in order to elucidate the early steps of signal transduction leading to the production of the apoplastic oxidative burst. •  Hydrogen peroxide production by elicited bean cells was monitored with luminol-or xylenol-orange-based assays. •  Pretreatment with forskolin, dibutyryl cAMP or the Ca ionophore A23187 enhanced the production of reactive oxygen species (ROS).