Abstract
Field-grown plants experience cycles of drought stress and recovery due to variation in soil moisture status. Physiological, biochemical and transcriptome responses instigated by recovery are expected to be different from drought stress and non-stressed state. Such responses can further aid or antagonize the plant's interaction with the pathogen. However, at molecular level, not much is known about plant-pathogen interaction during drought recovery. In the present study, we performed a microarray-based global transcriptome profiling and demonstrated the existence of unique transcriptional changes in Arabidopsis thaliana inoculated with Pseudomonas syringae pv. tomato DC3000 at the time of drought recovery (drought recovery pathogen, DRP) when compared to the individual drought (D) or pathogen (P) or drought recovery (DR). Furthermore, the comparison of DRP with D or DR and P transcriptome revealed the presence of a few common genes among three treatments. Notably, a gene encoding proline dehydrogenase (AtProDH1) was found to be commonly up-regulated under drought recovery (DR), DRP and P stresses. We also report an up-regulation of pyrroline-5-carboxylate biosynthesis pathway during recovery. We propose that AtProDH1 influences the defense pathways during DRP. Altogether, this study provides insight into the understanding of defense responses that operate in pathogen-infected plants during drought recovery.