Spatial-specific regulation of root development by phytochromes inArabidopsis thaliana

Abstract

Distinct tissues and organs of plants exhibit dissimilar responses to light exposure--cotyledon growth is promoted by light, whereas hypocotyl growth is inhibited by light. Light can have different impacts on root development, including impacting root elongation, morphology, lateral root proliferation and root tropisms. In many cases, light inhibits root elongation. There has been much attention given to whether roots themselves are the sites of photoperception for light that impacts light-dependent growth and development of roots. A number of approaches including photoreceptor localization in planta, localized irradiation and exposure of dissected roots to light have been used to explore the site(s) of light perception for the photoregulation of root development. Such approaches have led to the observation that photoreceptors are localized to roots in many plant species, and that roots are capable of light absorption that can alter morphology and/or gene expression. Our recent results show that localized depletion of phytochrome photoreceptors in Arabidopsis thaliana disrupts root development and root responsiveness to the plant hormone jasmonic acid. Thus, root-localized light perception appears central to organ-specific, photoregulation of growth and development in roots.

D‐Root: a system for cultivating plants with the roots in darkness or under different light conditions

“…The majority of photoreceptors and light signaling modules are expressed in roots (Warnasooriya and Montgomery, ). As light modifies root growth, we decided to study the role of photoreceptors in root development using D‐Root.…”

“…In addition, positive gravitropism reinforces root growth in the dark as they bury underground while following the gravity vector (Mullen et al ., ). It is particularly intriguing that the majority of light photoreceptors and signaling components, as well as some circadian clock modules, are expressed in roots (Warnasooriya and Montgomery, ). In fact, in laboratory conditions, light affects root organogenesis (growth rate and LR production), orientation and pigmentation (Usami et al ., ; Sassi et al ., ; Moni et al ., ).…”

Regulation of Photomorphogenic Development by Plant Phytochromes

“…Plants dynamically adjust their architecture to optimize growth and development under fluctuating light conditions, which include the deceleration of hypocotyl elongation, cotyledon opening, leaf greening, root elongation, lateral root proliferation, and root tropisms [49,50]. Root elongation and root hair formation are mediated by phyA and phyB under FR/blue and R light conditions, respectively.…”

“…Root elongation and root hair formation are mediated by phyA and phyB under FR/blue and R light conditions, respectively. Furthermore, lateral root production is regulated by phytochromes, in which phyA, phyB, and phyE stimulate lateral root production, while phyD inhibits the lateral root development in Arabidopsis [49]. In monocots, phyA and phyB are also known to be responsible for light-regulated inhibition of the seminal root elongation [49,51].…”

“…Furthermore, lateral root production is regulated by phytochromes, in which phyA, phyB, and phyE stimulate lateral root production, while phyD inhibits the lateral root development in Arabidopsis [49]. In monocots, phyA and phyB are also known to be responsible for light-regulated inhibition of the seminal root elongation [49,51]. In fact, photoreceptors occur ubiquitously over the plant body including roots, although they are most abundant in shoots [52].…”