Root meristem growth factor (RGF) peptide signaling as a molecular bridge between root development and non-lethal thermal stress adaptation

Although lethal heat shock and moderately high temperatures have been studied in detail, the effects of non-lethal high temperatures on root development remain largely unknown. We defined 31°C as a non-lethal thermal stress in Arabidopsis thaliana and examined its impact on root growth using phenotypic analyses and developmental-zone-specific transcriptomics.

Under the non-lethal thermal stress (31°C), primary root growth, meristem size, and superoxide (O₂-) accumulation were all reduced, and the distribution of the meristem master regulator PLETHORA2 (PLT2) became restricted. Transcriptome analysis revealed a strong downregulation of RGFs, RGFRs, and PLT2. Mutants of these genes were more sensitive to the stress, whereas RGF1 treatment restored meristem size, increased O₂- levels, and expanded the distribution of PLT2 protein.