Coordinated Regulations of mRNA Synthesis and Decay during Cold Acclimation in Arabidopsis Cells.

Plants possess a cold acclimation system to acquire freezing tolerance through pre-exposure to non-freezing low temperatures. The transcriptional cascade of C-repeat binding factors (CBFs)/dehydration response element-binding factors (DREBs) is considered a major transcriptional regulatory pathway during cold acclimation. However, little is known regarding the functional significance of mRNA stability regulation in the response of gene expression to cold stress. The actual level of individual mRNAs is determined by a balance between mRNA synthesis and degradation. Therefore, it is important to assess the regulatory steps to increase our understanding of gene regulation. Here, we analyzed temporal changes in mRNA amounts and half-lives in response to cold stress in Arabidopsis cell cultures based on genome-wide analysis. In this mRNA decay array method, mRNA half-life measurements and microarray analyses were combined. In addition, temporal changes in the integrated value of transcription rates were estimated from the above two parameters using a mathematical approach. Our results showed that several cold-responsive genes, including Cold-regulated 15a, were relatively destabilized, whereas the mRNA amounts were increased during cold treatment by accelerating the transcription rate to overcome the destabilization. Considering the kinetics of mRNA synthesis and degradation, this apparently contradictory result supports that mRNA destabilization is advantageous for the swift increase in CBF-responsive genes in response to cold stress. To understand temporal changes in mRNA amount and stability in response to cold stress, we performed mRNA decay array using Arabidopsis T87 cells under the control condition (22°C) and 6 h, 12 h, 24 h, and 36 h after the start of cold treatment at 4°C. Cells were collected prior to the cordycepin treatment (0 h) and 0.5, 2, 4 h after cordycepin addition in the control cells. Incubation time after cordycepin addition was 4, 8 and 12 h in the cold treated cell.