Growth temperature affects inflorescence architecture in Arabidopsis thaliana

Plants adjust their growth and development to ensure survival under adverse environmental conditions. Nonoptimal growth temperatures can have a major impact on biomass and crop yield. A detailed phenotypic analysis (number and length of rosette and cauline branches, flowers, and buds) in Arabidopsis thaliana revealed that growth temperatures below (12 and 17 degrees C) and above (27 and 32 degrees C) the control 22 degrees C affect branching and flowering. The elongation of internodes on the main stem and of primary branches at cauline leaves is reduced at lower temperatures and increased at higher temperatures. Similar results are observed in plants treated before or after bolting. Our data therefore indicate that plants that have transitioned to the reproductive stage before treatment are slightly less affected by temperature variations than plants that are in their vegetative stage. Our results also suggest that plants need to reach a maximum height (internodes length) before they begin forming floral meristems and that this "maximum height" is dependent on the growth temperature. Plants grown at 17 degrees C show a slightly reduced branching, while those at 27 degrees C show increased branching. This suggests that apical dominance is a temperature-dependent phenomenon. This is, to our knowledge, the first extensive analysis of the effect of temperature on Arabidopsis inflorescence development.