Overexpression of the Peach Transcription Factor Early Bud-Break 1 Leads to More Branches in Poplar.

Xuehui Zhao,Li Liu,Chen Li,Ling Li,Xiude Chen,Xiling Fu,Qiuping Tan,Binbin Wen

doi:10.3389/fpls.2021.681283

Xuehui Zhao, Li Liu + Show 6 more

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https://doi.org/10.3389/fpls.2021.681283

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Abstract

Shoot branching is an important adaptive trait that determines plant architecture. In a previous study, the Early bud-break 1 (EBB1) gene in peach (Prunus persica var. nectarina) cultivar Zhongyou 4 was transformed into poplar (Populus trichocarpa). PpEBB1-oe poplar showed a more branched phenotype. To understand the potential mechanisms underlying the EBB1-mediated branching, transcriptomic and proteomics analyses were used. The results showed that a large number of differentially expressed genes (DEGs)/differentially expressed proteins (DEPs) associated with light response, sugars, brassinosteroids (BR), and nitrogen metabolism were significantly enriched in PpEBB1-oe poplar. In addition, contents of sugars, BR, and amino acids were measured. Results showed that PpEBB1 significantly promoted the accumulation of fructose, glucose, sucrose, trehalose, and starch. Contents of brassinolide (BL), castasterone (CS), and 6-deoxocathasterone (6-deoxoCS) were all significantly changed with overexpressing PpEBB1. Various types of amino acids were measured and four of them were significantly improved in PpEBB1-oe poplar, including aspartic acid (Asp), arginine (Arg), cysteine (Cys), and tryptohpan (Trp). Taken together, shoot branching is a process controlled by a complex regulatory network, and PpEBB1 may play important roles in this process through the coordinating multiple metabolic pathways involved in shoot branching, including light response, phytohormones, sugars, and nitrogen.

Highlights

Bud-break 1 (EBB1), an ethylene-responsive factor (ERF), which is a transcription factor, is the putative orthologue of dornröschen/dornröschen-like (DRN/L); it is known as enhancer of shoot regeneration1/2 (ESR1/2) in Arabidopsis (Chandler, 2018)
It has been considered that Early bud-break 1 (EBB1) defined a conserved mechanism for the control of bud-break in woody perennials (Busov et al, 2016)
We found that PpEBB1-oe poplars showed a more branched phenotype, which was proposed by Yordanov et al (2014)

Summary

Introduction

Bud-break 1 (EBB1), an ethylene-responsive factor (ERF), which is a transcription factor, is the putative orthologue of dornröschen/dornröschen-like (DRN/L); it is known as enhancer of shoot regeneration1/2 (ESR1/2) in Arabidopsis (Chandler, 2018). Overexpression of EBB1 in poplar caused spontaneous regeneration from leaf disks and cambium-derived callus, resulting in an increased proliferation of sylleptic branches (Yordanov et al, 2014). Shoot branching is regulated by both endogenous and environmental signals, including light, nutrition, hormones, and key genes (Drummond et al, 2015; Barbier et al, 2019). Some studies suggested that auxin export was important for young branch growth but not essential to trigger initiation of bud growth, whereas cytokinin and strigolactone have been identified as early regulators of bud outgrowth, the role was not fully understood (Dun et al, 2012; Barbier et al, 2019; Chabikwa et al, 2019). Nitrogen and phosphorus supply leads to more branches in petunia (Petunia hybrida; Drummond et al, 2015) and Arabidopsis (de Jong et al, 2014)

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