In our study we show that the antagonistic activity of key plant transcription factors involved in phytochrome red light photoreceptors signaling (PIFs and HY5) optimize photosynthetic pigment production in response to environmental cues. If we are to mitigate the impact of variable weather patterns on agriculture, it is critical to advance our understanding of the basis of plant responses to environmental variations.

Global climate alterations will bring together the combination of light and temperature changes and will require an understanding of signal convergence. While light and temperature are recognized as the most prominent environmental factors modulating plant photosynthetic metabolism, how the seasonal and daily adjustments are achieved is not understood. Plants, as sessile and photosynthetic organisms, have to constantly adjust their growth and development in response to the environment. However, sudden changes in light or temperature conditions can trigger changes in HY5 and PIFs abundance that adjust the expression of common target genes to optimise photosynthetic performance and growth. In the regulation of photopigment biosynthesis genes, HY5 and PIFs do not operate alone, but with the circadian clock. This antagonistic regulatory module provides a simple, direct mechanism through which environmental change can redirect transcriptional control of genes required for photosynthesis and photoprotection. Here we demonstrate that by directly targeting a common promoter cis-element (G-box), HY5 and PIFs form a dynamic activation-suppression transcriptional module responsive to light and temperature cues. While the bZIP transcription factor LONG HYPOCOTYL 5 (HY5), a potent PIF antagonist, promotes photosynthetic pigment accumulation in response to light. Phytochromes accomplish this partly through the suppression of PHYTOCHROME INTERACTING FACTORS (PIFs), negative regulators of chlorophyll and carotenoid biosynthesis. This is particularly important during seedling establishment when the phytochrome photoreceptors activate photosynthetic pigment production for photoautotrophic growth.

The ability to interpret daily and seasonal alterations in light and temperature signals is essential for plant survival.

Dark Light by S.J. Davis