Transcriptome profiles underlying the spermidine-elevated resistance to high temperature in the radish Raphanus sativus

Radish is a common crop and vulnerable to high temperature. Pretreatment with spermidine could effectively elevate the resistance of radish to high temperature. Up to date, the underlying mechanisms remain unknown. In the present study, radish seedlings were pretreated with spermidine and then exposed to high temperature. The leaves were collected for transcriptome sequencing and the results were compared with samples only exposed to high temperature and samples consistently cultured at normal temperature. The differentially expressed genes were identified and validated using real-time quantitative PCR. Finally, the results revealed that pretreatment with spermidine significantly up-regulated the transcription level of anti-oxidation enzymes, heat-shock proteins, and proteins involved in the photosynthetic process, in comparison with treatments with high temperature and room temperature, suggesting that pretreatment with spermidine increased heat tolerance in radish probably through minimizing the harms caused by peroxidation, accelerating the corrections or degradation of misfolded proteins, and promoting photosynthesis. These findings preliminarily uncovered the molecular mechanisms underlying the spermidine-promoted heat resistance in radish.