Plant Photobiology: From Molecules to Function

Being photoautotrophic, plants have evolved a number of highly sensitive and plastic signal-response systems for modulating growth and development in response to ever changing light conditions. These responses are collectively termed photomorphogenesis. Though distinct from the photosynthetic properties of a plant, photomorphogenesis can impact processes from seed germination and seedling establishment to flowering and reproduction, including both photosynthetic and non-photosynthetic events. A number of specific photoreceptor proteins have evolved to allow plants to sense changes in light quality and intensity; changes that are both rapid and transient, as well as diurnal and seasonal. Among the photoreceptors most intensively studied are the red/far red light-absorbing phytochromes and the UV-A/blue light-absorbing cryptochromes and phototropins. While the phytochromes and crytochromes appear to most frequently modulate transcriptional changes that result in broad developmental shifts, the phototropins appear to mediate changes in organellar, cellular and organ movement responses that do not result from direct receptor signaling to the nucleus. Each of these receptors, as well as several others, can have direct and indirect impacts on the circadian responses of plants. Moreover, in a large number of cases, be they transcriptionally regulated or not, photomorphogenic responses involve alterations in plant hormone sensing, signaling and response; again underlining the highly plastic and integrative nature of plant responses to changes in the light environment. In this Research Topic reports touching on many of these aspects of plant biology are presented. Each results directly or as an extension of the 2015 International Symposium on Plant Photobiology which was held in Austin, TX in late May.