Natural variation uncouples HSFA2 induction from volatile-induced thermotolerance in Arabidopsis thaliana.

Volatile organic compounds can prime plants for improved thermotolerance, but how volatile perception is coupled with heat-protective transcriptional programs across natural variation remains unclear. We compared six Arabidopsis thaliana accessions for early induction of the thermomemory regulator HSFA2 following 30 min of priming with mild heat or seven reactive short-chain volatiles and assessed survival after a priming–recovery–lethal heat regime. Several reactive GLVs enhanced survival across the panel; the magnitude of both survival and early HSFA2 induction was accession-dependent. Across accessions, priming outputs were decoupled from canonical thermomemory markers: Cvi-0 exhibited uniformly weak HSFA2 induction yet retained high survival after T2H priming, whereas C24 showed low HSFA2 responsiveness to mild heat but pronounced volatile-driven HSFA2 induction. Early induction of class A1 heat shock factor genes (HSFA1 paralogs) and the thermotolerance effector HSP101 also varied among accessions, further supporting the uncoupling of survival outcomes from core heat-shock regulators. We then contrasted Col-0 and Cvi-0 using transcriptome profiling under control and T2H conditions. Col-0 strengthened a canonical heat-response module during T2H exposure, whereas Cvi-0 showed weaker induction of HSFA2, HSFA7, HSP101, and multiple small heat shock protein genes, indicating reduced T2H responsiveness in Cvi-0 despite strong priming. Instead, Cvi-0 activated defense- and detoxification-associated programs and specialized metabolism, highlighting candidate modules that include ESP, ALD1, PR5, GSTU10, and CYP71B15. Together, these results demonstrate that volatile-primed thermotolerance can be achieved without a strongly HSFA2-dominated transcriptional program, revealing alternative regulatory routes that may be leveraged to enhance heat resilience.