Integration of light and hormone response during seedling establishment

Abstract

Being sessile in nature, plants have evolved versatile adaptive mechanisms to adjust to fluctuating light environments to optimize performance and fitness. Apart from its primary role in photosynthesis, light influences almost all aspects of plant life including seed germination, seedling establishment, flowering transition. Photomorphogenesis is a light-regulated process that helps the seedling establish in its ecological niche and embark into its life that may sometimes continue for hundreds of years. Absence of light initiates an alternative growth mode called skotomorphogenesis where the default pathways operate, aiding the seedling extend towards the light source. These default molecular networks respond to light perception and are often suppressed in the presence of light. Apart from the light-dependent growth plasticity, endogenous genetic factors work independent of light and help appropriate shoot and root growth. Recent works have uncovered molecular links between the endogenous growth modules and the light-dependent growth, which often converge to the transcription factors involved in phytohormone biosynthesis or signalling. Here, we discuss the advancement made in the past decade in light-dependent seedling morphogenesis and its link with the endogenous plant morphogenetic pathways.