Combined Use of Genome-Wide Association Data and Correlation Networks Unravels Key Regulators of Primary Metabolism in Arabidopsis thaliana

PLoS Genet. 2016 Oct 19;12(10):e1006363. doi: 10.1371/journal.pgen.1006363. eCollection 2016 Oct.

Abstract

Plant primary metabolism is a highly coordinated, central, and complex network of biochemical processes regulated at both the genetic and post-translational levels. The genetic basis of this network can be explored by analyzing the metabolic composition of genetically diverse genotypes in a given plant species. Here, we report an integrative strategy combining quantitative genetic mapping and metabolite‒transcript correlation networks to identify functional associations between genes and primary metabolites in Arabidopsis thaliana. Genome-wide association study (GWAS) was used to identify metabolic quantitative trait loci (mQTL). Correlation networks built using metabolite and transcript data derived from a previously published time-course stress study yielded metabolite‒transcript correlations identified by covariation. Finally, results obtained in this study were compared with mQTL previously described. We applied a statistical framework to test and compare the performance of different single methods (network approach and quantitative genetics methods, representing the two orthogonal approaches combined in our strategy) with that of the combined strategy. We show that the combined strategy has improved performance manifested by increased sensitivity and accuracy. This combined strategy allowed the identification of 92 candidate associations between structural genes and primary metabolites, which not only included previously well-characterized gene‒metabolite associations, but also revealed novel associations. Using loss-of-function mutants, we validated two of the novel associations with genes involved in tyrosine degradation and in β-alanine metabolism. In conclusion, we demonstrate that applying our integrative strategy to the largely untapped resource of metabolite-transcript associations can facilitate the discovery of novel metabolite-related genes. This integrative strategy is not limited to A. thaliana, but generally applicable to other plant species.

MeSH terms

  • Alanine / genetics
  • Alanine / metabolism
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins* / genetics
  • Arabidopsis Proteins* / metabolism
  • Chromosome Mapping
  • Gene Expression Regulation, Plant
  • Genetic Variation
  • Genome, Plant
  • Genome-Wide Association Study*
  • Genotype
  • Quantitative Trait Loci / genetics*
  • Statistics as Topic
  • Tyrosine / genetics
  • Tyrosine / metabolism

Substances

  • Arabidopsis Proteins
  • Tyrosine
  • Alanine

Grants and funding

We acknowledge financial support by the Max Planck Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.