WRKY transcription factors and ethylene signaling modify root growth during the shade-avoidance response. Issue 2 (27th October 2021)

• Record Type: Journal Article
• Authors: Rosado, Daniele; Ackermann, Amanda; Spassibojko, Olya; Rossi, Magdalena; Pedmale, Ullas V
• Is Part Of: Plant physiology. Volume 188:Issue 2(2022)
• Page Start: 1294
• Page End: 1311
• Publication Date: 2021-10-27
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1093/plphys/kiab493
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract: Shade-intolerant plants rapidly elongate their stems, branches, and leaf stalks to compete with neighboring vegetation, maximizing sunlight capture for photosynthesis. This rapid growth adaptation, known as the shade-avoidance response (SAR), comes at a cost: reduced biomass, crop yield, and root growth. Significant progress has been made on the mechanistic understanding of hypocotyl elongation during SAR; however, the molecular interpretation of root growth repression is not well understood. Here, we explore the mechanisms by which SAR induced by low red:far-red light restricts primary and lateral root (LR) growth. By analyzing the whole-genome transcriptome, we identified a core set of shade-induced genes in roots of Arabidopsis ( Arabidopsis thaliana ) and tomato ( Solanum lycopersicum ) seedlings grown in the shade. Abiotic and biotic stressors also induce many of these shade-induced genes and are predominantly regulated by WRKY transcription factors. Correspondingly, a majority of WRKY genes were among the shade-induced genes. Functional analysis using transgenics of these shade-induced WRKYs revealed that their role is essentially to restrict primary root and LR growth in the shade; captivatingly, they did not affect hypocotyl elongation. Similarly, we also found that ethylene hormone signaling is necessary for limiting root growth in the shade. We propose that during SAR, shade-induced WRKY26, 45, and 75, and ethylene reprogram gene expression in the root to restrict its growth and development. Abstract : Low red:far-red shade induces genes in roots regulated by WRKY transcription factors and ethylene, restricting primary and lateral root growth.