Transcriptome analysis reveals genes expression pattern of Spirodela polyrhiza response to heat stress.

With global warming, high-temperature stress has become an essential abiotic factor affecting plant growth and survival. However, little knowledge was available of the molecular mechanism that aquatic plants respond to this stress. In the present study, we explore the adaptation mechanism of Spirodela polyrhiza, a surface-water-grown duckweed species broadly distributed worldwide to high temperatures, and analyze its gene expression pattern of S. polyrhiza under heat stress. Three temperature stress treatments, including room temperature group (CK), middle high-temperature group (MTS), and high-temperature group (45 °C, HTS) were set. The results showed that the contents of SOD first increased and then decreased, and those of MDA showed an upward trend under elevated high-temperature stress. According to the transcriptome data, 3145, 3487, and 3089 differently expressed genes (DEGs) were identified between MTS and CK, HTS and CK, and HTS and MTS, respectively. The transcription factors (TFs) analysis showed that 14 deferentially expressed TFs, including HSF, ERF, WRKY, and GRAS family, were responsive to heat stress, suggesting they might play vital roles in improving resistance to heat stress. In conclusion, S. polyrhiza could resist high temperatures by increasing SOD activity and MDA at the physiological level. Several transcription factors, energy accumulation processes, and cell membranes were involved in high-temperature stress at the molecular level. Our findings are helpful in better grasping the adaptation rules of some aquatic plants to high temperatures.