Abstract
It is known that translation from most of mRNA is inhibited in plants exposed to abiotic stresses (translationally inhibited). However, a subset of mRNA maintains the translational level under these stress conditions (preferentially translated). Previously, we have identified mRNAs which maintain translation under heat stress (HS) in Arabidopsis thaliana T87 cells. It is thought that 5'UTRs have an important role in translational regulation under abiotic stress. Therefore, in this work, the importance of 5'UTRs on translational regulation has been examined in detail. At first, two expression vectors that include a GUS gene with At1g77120 5'UTR (preferentially translated) or At3g47610 5'UTR (translationally inhibited) were constructed. The generated transformants were incubated under normal or HS condition, and the translational state of each chimeric GUS mRNA was analyzed. As a result, they showed the same profile as their original mRNAs. This result indicates the importance of 5'UTR as the determinant of a translational state under HS. The sequence motifs of 5'UTR involved in translational regulation under HS are presented as well.
