CDK8 coordinates jasmonate-induced immunity with sulfur-responsive defense in <i>Arabidopsis</i>.

Abstract

Plant immunity draws heavily on carbon-, nitrogen-, and sulfur-based precursors for the deployment of specialized defense compounds. The jasmonate signaling pathway promotes expression of metabolically costly defenses, often at the expense of growth. How plants coordinate growth-defense tradeoffs with changes in nutrient availability remains poorly understood. Here, we identify CYCLIN-DEPENDENT KINASE 8 (CDK8) as a transcriptional regulator that restrains growth and reduces seed yield under conditions of heightened jasmonate signaling in <i>Arabidopsis thaliana</i> and further show that CDK8 shapes immune responses according to sulfur availability. Transcript and metabolite profiling showed that CDK8 amplifies jasmonate-triggered immunity, including robust accumulation of glucosinolates, camalexin, and sulfur-rich defensin peptides under sulfur-replete conditions. Strikingly, sulfur limitation triggered a CDK8-dependent transcriptional switch that suppressed defensins and glucosinolates while coordinately inducing camalexin, a defense metabolite requiring substantially lower sulfur investment. These findings establish CDK8 as a regulator that integrates jasmonate signaling with sulfur nutritional status to shape the composition of plant immune responses.