Effects of temperature on the timeliness of eDNA/eRNA: A case study of Fenneropenaeus chinensis

Analysis of environmental DNA (eDNA) has been successfully used to detect organisms in various aquatic environments. Although eDNA has been shown to persist for long periods of time in environmental samples, the efficacy of eDNA/eRNA based tools is highly dependent on degradation of the molecule, which subsequently has a great impact on the timeliness of the detection results. Environmental RNA (eRNA) is considered an excellent complementary tool because most researchers believe that RNA degrades faster than DNA in vitro. However, to the best of our knowledge, published research related to eRNA is very limited. To address an important knowledge gap, this study focused on the relationship between water temperature and the degradation of eDNA and eRNA. Changes in the concentration of eDNA and eRNA of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene from Fenneropenaeus chinensis were detected at four temperatures (10, 15, 20 and 25°C). The results show that the eDNA degradation rate increased at higher temperatures, with the degradation rate constants ranging from 0.011 to 0.486 h-1 and the degradation time ranging from 8 to 383 h for eDNA. For eRNA, the degradation rate constants ranged from 0.190 to 0.379 h-1 and the degradation time ranged from 11 to 22 h. eRNA showed better stability under temperature change and maintained a faster degradation rate at low temperatures. These results answer the questions that eRNA and eDNA degradation rate which is fast or slow of the current research. Furthermore, this study may suggest the potential superiority of eRNA over eDNA and promote the further study of eRNA in future research.