Specific and pleiotropic regulation fine-tune primary metabolism and impact on plant reproduction, development and growth

FUSARI, CORINA M.; KOOKE, RIK; SULPICE, RONAN; LAUXMANN, MARTIN A.; ANNUNZIATA, MARIA GRAZIA; KEURENTJES, JOOST J. B.; STITT, MARK

Cambridge

Congreso; GARNET Meeting: Natural variation as a tool for gene discovery and crop improvement'; 2016

GARNET

Plant primary metabolism is regulated at multiple levels to integrate signals about resource availability, environment conditions and developmental cues. The genetic basis of this network has previously been explored by mapping QTL for metabolites. A more direct approach would be to search for polymorphisms that determine the abundance or properties of enzymes. We have applied genome-wide association (GWA) mapping to 349 Arabidopsis accessions to identify QTL for 24 enzyme activities. We were interested to determine whether genetic variation in enzyme activity is mainly due to cis-QTL in structural genes for enzymes, or in regulatory trans-QTL. We also mapped QTL for 13 metabolites that are transformed by these enzymes, some structural components and biomass. Correlation analysis revealed strong connectivity between many traits, as in many previous studies. The strongest QTL were cis-QTL. These were detected in six structural genes and were responsible for four enzyme activity QTL and two metabolite level QTL. A strong cis-QTL for UGPase activity located in the promoter region of UGP1 is maintained through balancing selection. Variation in acid Invertase activity mapped to both the promoter and the coding region of VAC-INV, and reflected multiple evolutionary events. Both genes, together with APL1, which associated to AGPase activity, are important for correct development of flower and seeds. We also detected many trans-QTL. They included transcription factors, E3 ligases, protein targeting components and protein kinases. A major pleiotropic QTL located in the genomic region containing ACD6 in Chr4 was also detected. This QTL associated with six enzyme activities, three metabolite levels and biomass. These traits are co-ordinately determined by different ACD6 alleles, pointing to a trade-off between central metabolism and defence against biotic stress.