The Effects of Carbon Dioxide and Temperature on microRNA Expression in Arabidopsis Development

Elevated levels of CO2 and temperature can both affect plant growth and development, but the molecular pathways and signaling mechanisms regulating these processes are still obscure. MicroRNAs function to silence gene expression, and environmental stresses can alter their expressions to modulate plant phenotypes. Here we show, using the small RNA-sequencing method, the identification of microRNAs that are changed significantly in expression by either doubling the atmospheric CO2 concentration or by increasing temperature 3-6˚C. Notably, nearly all CO2-influenced microRNAs are also affected by elevated temperature. Using the RNA-sequencing method, we determine strongly correlated expression changes between miR156/157 and miR172 and their target transcription factors under elevated CO2 concentration, suggesting a mechanism for a CO2-induced early flowering phenotype. Similar correlations are also revealed for microRNAs acting in auxin-signaling, stress responses, and potential cell wall carbohydrate synthesis. Our results demonstrate that elevated CO2 and elevated temperature can signal microRNA expressions to affect Arabidopsis growth and development, and microRNA regulation of flowering time might underlie the onset of flowering affected by increasing CO2.