Transcriptional Profiling Implicates Novel Interactions between Abiotic Stress and Hormonal Responses in Thellungiella

Thellungiella, an Arabidopsis-related halophyte, is an emerging model species for studies designed to elucidate molecular mechanisms of abiotic stress tolerance. Using a cDNA microarray containing 3628 unique sequences derived from previously reported libraries of stress-induced cDNAs of the Yukon ecotype of Thellungiella, we obtained transcript profiles of its response to drought, cold, high salinity and re-watering after drought. A total of 153 transcripts were found to be significantly differentially regulated under the conditions studied. Only six of these genes responded to all three stresses of drought, cold and salinity. Unlike in Arabidopsis, there were relatively few transcript changes in response to high salinity in this halophyte. Furthermore, drought responsive-transcripts in Thellungiella provided a link between the down-regulation of defense-related transcripts and the increase of endogenous abscisic acid during drought. This antagonistic interaction between drought and biotic stress response may potentially be beneficial for survival under drought stress. Intriguingly, changes of transcript abundance in response to cold implicate the involvement of jasmonic acid in the cold acclimation of Thellungiella. Taken together, our results provide useful starting points for more in depth analysis of Thellungiella’s extreme stress tolerance. Keywords: Abiotic stress response We used a custom cDNA microarray to perform an initial analysis of the molecular response of the Yukon ecotype of Thellungiella subjected to cold, drought, or drought followed by re-watering or salinity treatments. The 4 different sets of microarray exp are : 1) Control versus Cold 2) Control versus Drought 3) Drought versus Rewatering 4) Control versus Salinity In each set of microarray exp, we have performed 3 biological replicates (A, B, C) and technical replicate (dye swap) resulting in a total of 24 hybridizations.