Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0

Fredd Vergara,Christian Breuer,Jun Kikuchi

doi:10.1038/srep26515

Abstract

Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.

Highlights

A key realization of plant evolutionary genomics is that independent of their present ploidy status, all modern flowering plant genomes derive from repeated, episodic events of whole-genome duplication -polyploidization-1
Using the information generated with the metabolomics study, quantitative real-time PCR was performed on selected genes whose metabolic products showed the largest Nuclear magnetic resonance (NMR) variability between ploidies
Arabidopsis thaliana Col-0 diploids and autotetraploids analyzed at two ages (14- and 18-days-old) showed the same trends independent of their age

Summary

Introduction

A key realization of plant evolutionary genomics is that independent of their present ploidy status, all modern flowering plant genomes derive from repeated, episodic events of whole-genome duplication -polyploidization-1. Polyploidy is widespread in plants much remains unknown about how duplicate genes and genomes function in the early stages of polyploidization (neopolyploidization). It is unclear how the duplicate genes diverge in function during plant evolution but the common occurrence of polyploidy suggests an evolutionary advantage of having multiple sets of genetic material for adaptive evolution[3]. Allopolyploids of Arabidopsis thaliana have shown different levels of gene expression[11,12,13], DNA methylation[14], proteomic pattern[15]. The effect of allopolyploidization on plant physiology has been documented; no systematic study has been reported aiming to identify the metabolic differences produced by autopolyploidization in plants even if empirical estimates show that autopolyploidy and allopolyploidy frequencies are comparable among vascular plant species[20]. Our findings show that the metabolism of A. thaliana Col-0 displays strong differences correlated with the plant’s ploidy level

Methods

Results

Conclusion