Post-Transcriptional Regulation of Plant Gene Expression 565 RNA processing and Arabidopsis flowering

Plants control their flowering time in order to ensure that they reproduce under favourable conditions. The components involved in this complex process have been identified using a molecular genetic approach in Arabidopsis and classified into genetically separable pathways. The autonomous pathway controls the level of mRNA encoding a floral repressor, FLC, and comprises three RNA-binding proteins, FCA, FPA and FLK. FCA interacts with the 3′-end RNA-processing factor FY to autoregulate its own expression post-transcriptionally and to control FLC. Other components of the autonomous pathway, FVE and FLD, regulate FLC epigenetically. This combination of epigenetic and post-transcriptional control gives precision to the control of FLC expression and flowering time. Flowering time control The floral transition is complex, involving the integration of responses to environmental cues with an endogenous programmeof development. These responses aremediated by genetically separable pathways, which ensure that flowering occurs at a time that will maximize reproductive success