Natural variation unveils different modes of regulation for Arabidopsis metabolism under control and stress conditions

FUSARI, CORINA M.; LUZAROWSKA U; WU S.; RUSS A-K; JOUBÈS J; BROTMAN Y

Congreso; International Conference on Arabidopsis Research - ICAR 2021; 2021

North American Arabidopsis Steering Committee (NAASC)

Plant metabolism underpins plant growth by providing the building blocks and energy required for cell division, expansion, and maintenance and for the production of stress and defense metabolites. Understanding the regulation of plant metabolism is key to identify genetic factors involved in growth, metabolic responses to stress and defense mechanism. Through natural variation analyses of 300 Arabidopsis accessions and genome-wide association mapping studies (GWAS) we aimed: 1) to identify genes involved in lipid regulation during stress conditions and 2) to detect regulatory factors for defense metabolites. Highly significant correlations were seen for the different metabolic pathways in control and/or stress conditions, suggesting that there is a coordinate regulation of components. For lipid metabolism, stress conditions triggered differential accumulation of polyunsaturated triacylglycerols (puTAGs). PuTAG variation associated with a non-synonymous polymorphism (ns-SNP) at the 3-KETOACYL-COA SYNTHASE4, a gene member of the KCS family involved in the biosynthesis of VLCFA (very long chain fatty acids). Our studies suggest that KCS4 acts as a branch point in the fatty-acid fate during stress, channeling puFAs to puTAGs at different rates for different KCS4 alleles. Moreover, several defense compounds associated to ACELLERATED CELL DEATH6 (ACD6), an ankyrin-domain protein involved in a trade-off between growth and defense. Metabolic profiling of ACD6-allele-specific accessions and knock-down mutants showed differential metabolic responses in defense compounds pointing ACD6 as a regulatory hub for SAR (systemic acquire resistance) metabolites. We further quantified the effect of each SAR metabolite on the biomass trade-off. We found that a not well studied metabolite has a role in SAR, with its levels controlled by ACD6 alleles. These studies shed new light in understanding plant metabolic regulation and plasticity of metabolic responses under stress conditions.