Dynamics of Auxin and Cytokinin Metabolism during Early Root and Hypocotyl Growth in Theobroma cacao.

Alexandre Mboene Noah,Michal Karady,Karin Ljung,Rolande Eugenie Makondy Ango,Ioanna Antoniadi,Ondřej Novák,Rubén Casanova-Sáez,Nicolas Niemenak

doi:10.3390/plants10050967

Abstract

The spatial location and timing of plant developmental events are largely regulated by the well balanced effects of auxin and cytokinin phytohormone interplay. Together with transport, localized metabolism regulates the concentration gradients of their bioactive forms, ultimately eliciting growth responses. In order to explore the dynamics of auxin and cytokinin metabolism during early seedling growth in Theobroma cacao (cacao), we have performed auxin and cytokinin metabolite profiling in hypocotyls and root developmental sections at different times by using ultra-high-performance liquid chromatography-electrospray tandem mass spectrometry (UHPLC-MS/MS). Our work provides quantitative characterization of auxin and cytokinin metabolites throughout early root and hypocotyl development and identifies common and distinctive features of auxin and cytokinin metabolism during cacao seedling development.

Highlights

IntroductionCacao seeds germinate immediately after completing their maturation and they do not survive drying during ex situ conservation
In order to fill this gap, we have investigated the endogenous concentrations of auxin and cytokinin metabolites in cacao roots and hypocotyls, at different developmental stages and in different root developmental zones
To explore the dynamics of auxin and cytokinin metabolism during early seedling development in T. cacao, endogenous concentrations of auxin and cytokinin metabolites were quantified in cacao root and hypocotyl sections

Summary

Introduction

Cacao seeds germinate immediately after completing their maturation and they do not survive drying during ex situ conservation. The emergence of the radicle from the seed coat marks the transition from germination to the seedling establishment phase. Seedling establishment is a vulnerable process during which the plant grows heterotrophically until the first leaves emerge, and the seedling acquires autotrophic capacity. This phase is critical for plant survival and a determinant of yield in agricultural crops. The developmental window of seedling establishment in T. cacao can be centered on the root differentiation and hypocotyl elongation occurring between 4 and 10 days after germination [2]

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