Time course profiles in salt shock roots of Ceriops tagal

Transcriptional differentiation in response to environmental stresses plays critical roles in adaptation. Mangroves are dominant in intertidal zones and form dense forest at the sea-land interface, but little is known about the impact of transcriptional phenotype on their adaptation to the saline environments. To address this issue, we prepared customized chips containing cDNA from the root cDNA library of a mangrove species, Ceriops tagal, and then monitored the time-course transcript profiles in the roots by conducting a series of microarray experiments. Five durations of salt shock with 500 mM NaCl, namely 2, 5, 10, 24 and 192 hours, were included. A total of 88 unigenes that were recognized to be up- or down-regulated by salt shock and both gene categories in relation to stresses-induced responses and transcription factor activity were over-predominant. The stresses-responsive genes were significantly overrepresented, some of which were regulated in differential manners from their homologues genes in Arabidopsis. Specific transcriptional regulations were employed by C. tagal to cope with salt shock, which could benefit the salt-tolerant lifestyle of this mangrove species and possibly contribute to establishment of adaptation to the saline environments. A reference design was used to analyze gene expression differences. Salt stressed young roots were harvested from seedlings of C. tagal at the ends of each shock duration. Young roots of unshocked seedlings were used as controls and harvested at the same time. Three biological replicates were set up for each treatment and corresponding control, respectively, each containing a pool of total RNA from 4 seedlings. Salt stressed samples were compared with the corresponding controls at each time point by co-hybridizing to the customized cDNA arrays