Genetic dissection of crayfish (Procambarus clarkii) high temperature tolerance and assessment of the potential application in breeding of the HSP genes.

Red swamp crayfish (Procambarus clarkii) is an important freshwater aquaculture species in China. In the process of crayfish aquaculture, high temperature stress is common, which seriously affects its yield and quality. It is urgently recommended to improve these traits in the breed. However, the application of high-temperature tolerance genes in molecular breeding of crayfish has not been reported. In this study, transcriptome analysis was used to explore the high-temperature tolerance genes of crayfish. The results showed that genes related to energy metabolism, antioxidant, immunity and body restoration were involved in high temperature adaptation of crayfish. Based on the selected high temperature tolerance genes Heat Stress Protein 70 and Heat Stress Protein 90 (HSP70 and HSP90), the genetic variation of their open reading frames was investigated. Totally, three and four SNPs of HSP70 and HSP90, were obtained respectively. In addition, three high-temperature stress experiments were conducted on crayfish to identify favoured haplotypes. HSP70-1 and HSP90-1 are the favoured haplotypes of HSP70 and HSP90, respectively. Furthermore, a series of molecular markers were developed to identify the favoured haplotype combinations of HSP70 and HSP90. Finally, we propose a molecular breeding strategy to improve crayfish tolerance to high temperature, thereby providing a potential to increase crayfish yield. Together, this study provides a theoretical basis and molecular markers for the breeding of high-temperature tolerant crayfish.