A role of ETR1 in regulating leaf petiole elongation mediated by elevated temperature in <Emphasis Type="Italic">Arabidopsis</Emphasis>

Temperature fluctuation profoundly affects the plant growth and development. In this study, we show that ethylene receptor ETR1 is involved in regulating leaf petiole elongation mediated by higher temperatures (at 32 °C in this study). ETR1 loss-of-function mutant etr1-7 cannot elongate the leaf petiole at 32 °C as much as wild-type seedlings (WT). Overexpression of ETR1 in etr1-7 not only fully rescued the deficient in petiole elongation under higher temperature conditions but also caused longer petiole length under normal temperature conditions (22 °C). Plants with different mutant ETR1 alleles including etr1-7 etr1-1, and etr1-9 but not etr1-3 impair the petiole elongation mediated by elevated temperature. RNA-Seq analysis showed that hundreds of genes induced by elevated temperature in WT were not differentially expressed in etr1-7. Gene ontology enrichment analysis reveals that the molecular functions of these genes primarily relate to photosynthesis and protein degradation. Furthermore, genes involved in regulating organ elongation (such as BRI1-EMS-SUPPRESSOR 1, BES1), are significantly up-regulated in WT rather than in etr1-7 after the treatment of higher temperature. The results from this study suggest ETR1 is involved in regulating Arabidopsis response to elevated ambient temperature in both molecular and morphological levels.