Elevated CO₂ mitigates the impact of drought stress by upregulating glucosinolate metabolism in Arabidopsis thaliana

Elevated CO2 (eCO(2)) reduces the impact of drought, but the mechanisms underlying this effect remain unclear. Therefore, we used a multidisciplinary approach to investigate the interaction of drought and eCO(2) in Arabidopsis thaliana leaves. Transcriptome and subsequent metabolite analyses identified a strong induction of the aliphatic glucosinolate (GL) biosynthesis as a main effect of eCO(2) in drought-stressed leaves. Transcriptome results highlighted the upregulation of ABI5 and downregulation of WRKY63 transcription factors (TF), known to enhance and inhibit the expression of genes regulating aliphatic GL biosynthesis (e.g., MYB28 and 29 TFs), respectively. In addition, eCO(2) positively regulated aliphatic GL biosynthesis by MYB28/29 and increasing the accumulation of GL precursors. To test the role of GLs in the stress-mitigating effect of eCO(2), we investigated the effect of genetic perturbations of the GL biosynthesis. Overexpression of MYB28, 29 and 76 improved drought tolerance by inducing stomatal closure and maintaining plant turgor, whereas loss of cyp79f genes reduced the stress-mitigating effect of eCO(2) and decreased drought tolerance. Overall, the crucial role of GL metabolism in drought stress mitigation by eCO(2) could be a beneficial trait to overcome future climate challenges.