Effects of Light Intensity on Root Development in a D-Root Growth System

Frontiers in Plant Science, vol. 12, pp. 778382

Abstract

Plant development is highly affected by light quality, direction, and intensity. Under natural growth conditions, shoots are directly exposed to light whereas roots develop underground shielded from direct illumination. The photomorphogenic development strongly represses shoot elongation whereas promotes root growth. Over the years, several studies helped the elucidation of signaling elements that coordinate light perception and underlying developmental outputs. Light exposure of the shoots has diverse effects on main root growth and lateral root (LR) formation. In this study, we evaluated the phenotypic root responses of wild-type Arabidopsis plants, as well as several mutants, grown in a D-Root system. We observed that sucrose and light act synergistically to promote root growth and that sucrose alone cannot overcome the light requirement for root growth. We also have shown that roots respond to the light intensity applied to the shoot by changes in primary and LR development. Loss-of-function mutants for several root light-response genes display varying phenotypes according to the light intensity to which shoots are exposed. Low light intensity strongly impaired LR development for most genotypes. Only vid-27 and pils4 mutants showed higher LR density at 40 μmol m –2 s –1 than at 80 μmol m –2 s –1 whereas yuc3 and shy2-2 presented no LR development in any light condition, reinforcing the importance of auxin signaling in light-dependent root development. Our results support the use of D-Root systems to avoid the effects of direct root illumination that might lead to artifacts and unnatural phenotypic outputs.

Authors 5

1. Yohanna Evelyn Miotto

   Universidade Federal do Rio Grande do Sul

   Affiliation as printed

   Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

2. Cibele Tesser da Costa

   Universidade Federal do Rio Grande do Sul

   Affiliation as printed

   Departamento de Botânica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

3. Remko Offringa Aachen Plant Developmental Genetics Institute of Biology Leiden

   Leiden University

   Affiliation as printed

   Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Leiden, Netherlands

4. Jürgen Kleine‐Vehn

   University of Freiburg · BOKU University

   Affiliation as printed

   Center for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany

   Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria

   Department of Molecular Plant Physiology, Institute of Biology, University of Freiburg, Freiburg, Germany

5. Felipe dos Santos Maraschin corresponding

   Universidade Federal do Rio Grande do Sul

   Affiliation as printed

   Departamento de Botânica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

   Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil