Overexpression of a SOC1-Related Gene Promotes Bud Break in Ecodormant Poplars.

Daniela Gómez-Soto,Paolo M Triozzi,José M Ramos-Sánchez,Daniel Alique,Mariano Perales,Isabel Allona,Daniel Conde

doi:10.3389/fpls.2021.670497

Abstract

Perennial species in the boreal and temperate regions are subject to extreme annual variations in light and temperature. They precisely adapt to seasonal changes by synchronizing cycles of growth and dormancy with external cues. Annual dormancy–growth transitions and flowering involve factors that integrate environmental and endogenous signals. MADS-box transcription factors have been extensively described in the regulation of Arabidopsis flowering. However, their participation in annual dormancy–growth transitions in trees is minimal. In this study, we investigate the function of MADS12, a Populus tremula × alba SUPPRESSOR OF CONSTANS OVEREXPRESSION 1 (SOC1)-related gene. Our gene expression analysis reveals that MADS12 displays lower mRNA levels during the winter than during early spring and mid-spring. Moreover, MADS12 activation depends on the fulfillment of the chilling requirement. Hybrid poplars overexpressing MADS12 show no differences in growth cessation and bud set, while ecodormant plants display an early bud break, indicating that MADS12 overexpression promotes bud growth reactivation. Comparative expression analysis of available bud break-promoting genes reveals that MADS12 overexpression downregulates the GIBBERELLINS 2 OXIDASE 4 (GA2ox4), a gene involved in gibberellin catabolism. Moreover, the mid-winter to mid-spring RNAseq profiling indicates that MADS12 and GA2ox4 show antagonistic expression during bud dormancy release. Our results support MADS12 participation in the reactivation of shoot meristem growth during ecodormancy and link MADS12 activation and GA2ox4 downregulation within the temporal events that lead to poplar bud break.

Highlights

Woody perennial plants have acquired multiple adaptive mechanisms to coordinate their vegetative and reproductive growth with the seasonal weather changes (Cooke et al, 2012; Brunner et al, 2014)
We investigated the phylogenetic relationship of MADS-box genes in Arabidopsis thaliana and Populus trichocarpa by generating a maximum likelihood phylogenic tree using all annotated poplar and Arabidopsis full-length MADS-box protein sequences
Even though several SUPPRESSOR OF CONSTANS OVEREXPRESSION 1 (SOC1)-like genes were associated with dormancy release in trees (Voogd et al, 2015; Kitamura et al, 2016; Wang J. et al, 2020), the poplar SOC1-like members remain uncharacterized during dormancy phenology

Summary

Introduction

Woody perennial plants have acquired multiple adaptive mechanisms to coordinate their vegetative and reproductive growth with the seasonal weather changes (Cooke et al, 2012; Brunner et al, 2014). Deciduous woody plants cease meristem activity to establish a dormant state before winter; MADS12 Promotes Ecodormant Poplar Reactivation this is called endodormancy. The inability to initiate growth clearly distinguishes between endodormancy and the subsequent stage, called ecodormancy, when tree buds recover growth capacity in late winter without showing changes in morphology, maintaining plants cold protected (Groover and Cronk, 2017; Maurya and Bhalerao, 2017). Changes in photoperiod are constant every year in a given location, while the temperature is more variable among the years. This variation in the temperature has been exacerbated by global warming, causing significant ecological and economic detriment. A better understanding of the spring phenology’s molecular control in perennials is crucial to avoid global warming damages and help perennials resist future climate

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