FRUITFULL controls SAUR10 expression and regulates Arabidopsis growth and architecture

Marian Bemer,Jose M Muiño,Cristina Ferrándiz,Kerstin Kaufmann,Gerco C Angenent,Hilda Van Mourik

doi:10.1093/jxb/erx184

Abstract

MADS-domain transcription factors are well known for their roles in plant development and regulate sets of downstream genes that have been uncovered by high-throughput analyses. A considerable number of these targets are predicted to function in hormone responses or responses to environmental stimuli, suggesting that there is a close link between developmental and environmental regulators of plant growth and development. Here, we show that the Arabidopsis MADS-domain factor FRUITFULL (FUL) executes several functions in addition to its noted role in fruit development. Among the direct targets of FUL, we identified SMALL AUXIN UPREGULATED RNA 10 (SAUR10), a growth regulator that is highly induced by a combination of auxin and brassinosteroids and in response to reduced R:FR light. Interestingly, we discovered that SAUR10 is repressed by FUL in stems and inflorescence branches. SAUR10 is specifically expressed at the abaxial side of these branches and this localized activity is influenced by hormones, light conditions and by FUL, which has an effect on branch angle. Furthermore, we identified a number of other genes involved in hormone pathways and light signalling as direct targets of FUL in the stem, demonstrating a connection between developmentally and environmentally regulated growth programs.

Highlights

Plant growth and development are regulated by interplay between internal and external factors
In addition to genes involved in cytokinin and auxin signalling, such as the cytokinin degradases CKX5, CKX6, and CKX7, and genes encoding the AUX/indole-3-acetic acid (IAA) proteins IAA8 and IAA16, we found a remarkable number of genes that are implicated in the light-sensitive growth of hypocotyls, encoding transcription factors involved in the BZR-PIF-ARF-DELLA pathway (Bai et al, 2012; Oh et al, 2014)
We show here that the MADS domain transcription factor FUL is a pleiotropic regulator of plant development, which plays important roles in plant growth and architecture in addition to its well known functions in fruit development and flowering time

Summary

Introduction

Plant growth and development are regulated by interplay between internal and external factors. Plants with the same genotype show distinct phenotypic differences when, for example, grown at different temperatures or under different light conditions. This response to environmental conditions is mainly. The light-regulated growth of Arabidopsis hypocotyls has been thoroughly investigated and revealed to depend on physical interactions between transcription factors involved in auxin, GA, BR and light responses (Bai et al, 2012; Oh et al, 2014; Ross and Quittenden, 2016). Downstream growth-regulating genes can be induced or repressed by either the hormonemediated environmental response pathway or by the internal developmental pathway, integrating these two pathways in the growth response

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