Lessons Learned from the Studies of Roots Shaded from Direct Root Illumination.

Jozef Lacek,Katarzyna Retzer,Wolfram Weckwerth,Judith García-González

doi:10.3390/ijms222312784

Abstract

The root is the below-ground organ of a plant, and it has evolved multiple signaling pathways that allow adaptation of architecture, growth rate, and direction to an ever-changing environment. Roots grow along the gravitropic vector towards beneficial areas in the soil to provide the plant with proper nutrients to ensure its survival and productivity. In addition, roots have developed escape mechanisms to avoid adverse environments, which include direct illumination. Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light. Several studies have shown that direct illumination of roots alters their morphology, cellular and biochemical responses, which results in reduced nutrient uptake and adaptability upon additive stress stimuli. In this review, we summarize recent methods that allow the study of shaded roots under controlled laboratory conditions and discuss the observed changes in the results depending on the root illumination status.

Highlights

Plants have evolved a finely tuned network of signaling pathways to simultaneously adapt to multiple, continuously occurring changes in environmental conditions [1,2,3,4]
Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light
We summarize recent findings showing how established laboratory growth conditions, which include plant cultivation on growth medium with roots exposed to light, affect plant development and root responses to abiotic stresses

Summary

Introduction

Plants have evolved a finely tuned network of signaling pathways to simultaneously adapt to multiple, continuously occurring changes in environmental conditions [1,2,3,4]. External stimuli range from changing light conditions that affect the photosynthetic activity and serve as a signal to control organ growth, to energy-consuming responses to abiotic and biotic stresses that challenge plant productivity [1,5,6]. To ensure efficient plant growth and productivity we need to understand how plants adapt under less beneficial environmental conditions. Direct root illumination affects root growth alone but leads to altered communication between shoot and root, which modulates the distribution of signaling molecules and eventually reduces efficient nutrient uptake, and negatively affects the ability of plants to adapt to additive stress stimuli [6,9,25,26]. We summarize recent findings showing how established laboratory growth conditions, which include plant cultivation on growth medium with roots exposed to light, affect plant development and root responses to abiotic stresses

Standard Laboratory Conditions and Their Effects on Root Growth

Phytohormones

Additive Stress Responses under Direct Root Illumination

Findings

Conclusions