ZAT10 regulates root thermomorphogenesis via very-long-chain fatty acids signaling

Global warming drives moderate ambient temperature increases that trigger thermomorphogenesis–a developmental adaptation–in plants. Although shoot responses are well-characterized, the molecular mechanisms of root thermomorphogenesis remain poorly understood. In this study, we revealed that very-long-chain fatty acids (VLCFAs) are essential regulators of root thermomorphogenesis in Arabidopsis thaliana . Notably, the roots of wild-type plants showed increased growth/elongation at 28 °C, whereas those of kcs1 / 2 / 20 triple mutant deficient in VLCFA biosynthesis failed to exhibit temperature-dependent elongation. Transcriptomic profiling showed that the zinc-finger transcription factor ZAT10 was strongly induced in wild-type plant at 28 °C but not in kcs1 / 2 / 20 mutant. Additionally, loss of ZAT10 abolished root elongation and cell elongation in the maturation zone under warm conditions. Integration of RNA-seq and DAP-seq data revealed MYC2–a jasmonate-responsive transcription factor–as a direct downstream target of ZAT10. myc2 mutants displayed intermediate phenotypes, with attenuated cell and root growth at 28 °C. Moreover, MYC2 regulated additional target genes that play considerable roles in root thermomorphogenesis. Conclusively, these findings uncover a novel VLCFA–ZAT10–MYC2 signaling module that controls root cell elongation and root thermomorphogenesis, independent of well-known shoot pathway.