cyclic-gmp and Disease-Resistance

Cyclic guanosine-3',5'-monophosphate (cGMP) is recognized as an important second messenger in plants, mediating intracellular signal in important physiological processes, including the hypersensitive disease resistance response induced by avirulent pathogens. In this context, the analysis of cGMP levels in infected plants requires an accurate and specific detection method allowing its quantification. Here, we describe an assay based on the Alphascreen technology, developed for animal cells and further adapted and optimized for the detection of cGMP in plants. The method is applied for the measurement of cGMP in Arabidopsis thaliana plants challenged with an avirulent strain of Pseudomonas syringae pv. tomato. This protocol includes the extraction of cGMP, the assay procedure and the calculation of cGMP concentration.

Topics: Arabidopsis; Arabidopsis Proteins; Cyclic GMP; Disease Resistance; Plant Diseases; Plants

The infection of Arabidopsis thaliana plants with avirulent pathogens causes the accumulation of cGMP with a biphasic profile downstream of nitric oxide signalling. However, plant enzymes that modulate cGMP levels have yet to be identified, so we generated transgenic A. thaliana plants expressing the rat soluble guanylate cyclase (GC) to increase genetically the level of cGMP and to study the function of cGMP in plant defence responses. Once confirmed that cGMP levels were higher in the GC transgenic lines than in wild-type controls, the GC transgenic plants were then challenged with bacterial pathogens and their defence responses were characterized. Although local resistance was similar in the GC transgenic and wild-type lines, differences in the redox state suggested potential cross-talk between cGMP and the glutathione redox system. Furthermore, large-scale transcriptomic and proteomic analysis highlighted the significant modulation of both gene expression and protein abundance at the infection site, inhibiting the establishment of systemic acquired resistance. Our data indicate that cGMP plays a key role in local responses controlling the induction of systemic acquired resistance in plants challenged with avirulent pathogens.

Topics: Animals; Arabidopsis; Ascorbic Acid; Bacterial Proteins; Cyclic GMP; Disease Resistance; Gene Expression Regulation, Plant; Glutathione; Guanylate Cyclase; Plant Leaves; Plants, Genetically Modified; Proteome; Pseudomonas syringae; Rats; Transcriptome