Review: Mechanisms Underlying Alternative Polyadenylation in Plants–Looking in the Right Places

Recent years have seen an explosion of interest in the subject of alternative polyadenylation in plants. Connections between the polyadenylation complex and numerous developmental and stress responses are well-established. However, those that link stimuli with the functioning of the polyadenylation complex are much less well understood. To this end, it is imperative to clearly delineate the roles of the polyadenylation complex in both plant growth AND alternative polyadenylation. It is also necessary to understand the ways by which other molecular processes may contribute to alternative polyadenylation. This review discusses these issues, with a focus on instances that reveal mechanisms by which mRNA polyadenylation may be regulated. Insights that characterizations of mutants affected in the polyadenylation complex are discussed, as are the limitations of such characterizations when it comes to teasing out cause and effect. These limitations encourage explorations to other processes that are beyond the core polyadenylation complex. Two such processes that sculpt the plant transcriptome – transcription termination and the epigenetic control of transposon activity – also contribute to regulated poly(A) site choice. These subjects define “the right places” – molecular mechanisms that contribute to the wide-ranging control of gene expression via mRNA polyadenylation. •Genetic studies suggest mechanisms governing alternative polyadenylation in plants•It is often difficult to discern cause and effect in alternative polyadenylation•Different transcriptional mechanisms may be co-opted to regulate polyadenylation•Detailed biochemical studies of polyadenylation is needed to sort these issues out