CONICET | Buscador de Institutos y Recursos Humanos

Plants must be able to respond coordinately to changes in ambient temperature and light quality to maximize their fitness. Whereas several families of photoreceptors able to perceive different wavelengths and intensities have been characterized, the nature of the thermosensor(s) in plants remains obscure.Strikingly, many of the physiological responses triggered by both light and temperature are similar, which supposes that there are common response mechanisms. Using as model the temperature-dependent phenotype of mutants in the main red-light receptor, phytochrome B, we decided to address the study of the interaction between light and temperature during deetiolation. Our results show that plants sense temperature continuously, both in magnitude and duration. Further, phyB and other photoreceptors play key roles in buffering this response. Being phyB, important in the entire temperature range, while the blue light photoreceptors are more important at lower temperatures.We found that auxin plays an important role in these responses. Many auxin responsive genes and auxin reporter genes show genotype-temperature interactions, and this genotype-temperature interaction is lost in mutants defective in auxin biosynthetic genes. Using transcriptomic analysis we found a cytochrome P450 which showed an important temperature- genotype interaction in its expression pattern. We propose that this cytochrome might be necessary to regulate hypocotyl growth at lower temperatures under shade conditions, by an auxin-dependent mechanism.Overall, there appears to be different light dependent mechanisms: on the one hand, the best characterized, that promote the elongation at high temperatures; while, there are others that actively inhibit hypocotyl elongation at low temperatures.