Abstract text: Temperature-Induced Hypocotyl Elongation (TIHE) occurs when temperature moderately increases in a wide range of plants, including Arabidopsis thaliana. It is a relevant model for studying growth mechanisms because (i) hypocotyl elongation can be easily induced by increasing temperature and (ii) key molecular signaling components (e.g. Phytochrome-Interacting Factors, auxin and brassinosteroids) are well characterized. Cell wall pectin metabolism and its integrity sensing by specific receptors have also been reported to regulate growth. However, the contribution of pectin metabolism to TIHE, as well as its links with integrity sensing and hormonal signaling, remains unclear.

To address this question, this study aims at screening transgenic lines impaired in pectin metabolism, pectin integrity sensing and hormonal signaling. Hypocotyl elongation was measured in temperature-treated seedlings, which were then digested with polygalacturonase to hydrolyze pectins. Released oligogalacturonides (OGs) were subsequently analyzed by UPLC-ESI-MS. In parallel, a pectin integrity receptor was expressed in yeast and its binding ability to diverse OG patterns was then preliminarily characterized using microscale thermophoresis (MST). These first results provide new insights into the coordination between pectin metabolism, pectin integrity sensing, and hormonal signaling during TIHE.