Abstract:

To investigate the changes in gene expression under high temperature stress of pitaya, we studied key genes that respond to such stress and screened heat-resistant gene resources. In this study, RNA-seq was used to sequence pitaya stems treated at 25 ℃ and 40 ℃ for 24 h, and differentially that under were analyzed from the perspective of systems biology. The results showed that after pitaya was subjected to 40 ℃ for 24 h, and 2 408 genes showed significant changes compared with expression relative to 25 ℃, including 165 transcription factors, accounting for 6.7% of the total number of genes; the expression level was up-regulated by 2 to 587 times or down-regulated by 2 to 59 times. Heat shock proteins (HSPs) were particularly up-regulated after stress, and the top 10 up-regulated genes in differentially expressed genes were all HSPs, which may have important stress tolerance effects. By qPCR detection of the expression levels of these 10 HSPs in samples at different stress time, it was found that HSP18.2, HSP21, HSP22, HSP23.5 and HSP23.6 were up-regulated by more than 50 times after stress for 5 h, especially HSP21, which was up-regulated by 391 times after stress for 5 h and reached the highest level after stress for 10 h with an up-regulation of 589 times. The rapid response of HSP may be related to the high temperature tolerance of pitaya. HSP21 can be used as a signal gene for high temperature stress of pitaya.

Key words: pitaya, heat stress, heat shock protein, transcriptome