Assessing the functional role of a NAC gene of Arabidopsis, induced by nitric oxide and pathogens

Transcript profiling by cDNA-AFLP of Arabidopsis thaliana following treatment with the nitric oxide (NO) donor sodium nitroprusside (SNP) allowed the identification of a homologue of the ATAF2 protein (ANAC102), which is induced 1 h after treatment. The gene product belongs to the NAC protein family, which contains a number of transcription factors unique to plants, associated with development and stress response. Given the well-known involvement of NO in resistance to pathogens, Real-time RT-PCR was used to confirm the induction of ANAC102 by NO and then to analyse the expression level of ANAC102 in the interactions between A. thaliana Col-0 and virulent and avirulent strains of Pseudomonas syringae pv. tomato. The incompatible interaction resulted in a hypersensitive reaction in Arabidopsis. ANAC102 transcripts showed a 10-12-fold increase following NO treatment at 1 h, and about a 8-fold increase following inoculation with the bacterium at 10 and 24 h in the incompatible and compatible interactions, respectively. Arabidopsis Col-0 insertional mutants carrying a single, homozygous T-DNA insertion in the coding region of ANAC102 were obtained. Overexpressing Arabidopsis plants are also being produced. Studies are in progress to characterise the functional role of this gene in the resistance response, by the observing macroscopic and microscopic hypersensitive cell death, examining bacterial growth in plants, and analysing the expression of marker genes such as phenylalanine ammonia lyase (PAL) and of pathogenesis related protein 1 (PR 1) and defensin PFD1.2, both in wild type and mutant plants.