Barley transcript profiles under dehydration shock and drought stress treatments: a comparative analysis

A microarray including 1654 cDNAs, mainly derived from dehydration-shocked barley leaf tissues, was utilized to monitor expression changes in leaves of barley plants subjected to slow drying conditions (7 d and 11 d: 7d-WS and 11d-WS) in soil and after rehydration. The results were compared with those obtained under shock-like conditions imposed with a 6 h dehydration treatment. A total number of 173 transcripts (approximately 10% of all transcripts profiled) were declared up- or down-regulated in at least one of the conditions tested. The majority of the transcripts were regulated by only one of the drought treatments, with 57% of the differentially expressed transcripts exclusively affected in the dehydration shock treatment, 6% at 7d-WS, 14% at 11d-WS, and 6% after rehydration. Irrespective of the low percentage of transcripts (10%) with similar expression changes between shock and slow stress treatments, a sizeable portion of these transcripts shared a common expression trend under the different drought treatment conditions, as evidenced by low but significant correlations between the fast occurring and the 7d-WS and 11d-WS treatments (r=0.32 and 0.41, P=0.001, respectively). These results are discussed with respect to the merit of different dehydration treatments in the investigation of the changes in transcript profiling.