Temperature regulates Hsdmrt1 and Hsfoxl2 to affect gonadal development of the freshwater mussel Hyriopsis schlegelii

Sex reversal and sex ratio bias are common in mollusks, and temperature is one of the most important environmental factors influencing gonadal development and differentiation. Here, we obtained the full-lengh cDNAs of Hsdmrt1 and Hsfoxl2 and found that they were predominantly expressed in the gonads. Furthermore, Hsdmrt1 and Hsfoxl2 showed a sexually dimorphic expression pattern, with Hsdmrt1 biased toward males and Hsfolx2 favoring females. The expression of Hsfoxl2 was inhibited by Hsdmrt1. The sex ratios of 1–3-year-old mussels H. schlegelii were assessed, and the sex ratio bias was from male to female, accompanied by a significant decrease in log10 (Hsdmrt1/Hsfoxl2). And log10(Hsdmrt1/Hsfoxl2) value outside the interval [-2,1] was considered a stable sexual state. The sex reversal in H. schlegelii was reproduced by simulating temperatures, in which male mussels at 27 °C underwent sex reversal to become females; females at 19°C underwent sex reversal to males, and the log10(Hsdmrt1/Hsfoxl2) value was altered to be in the [-2,1] interval. These results support the hypothesis that an imbalance in the expression of either gene leads to a sex reversal and that this may be regulated by temperature. This study deepens our understanding of the mechanisms of sex reversal and gonadal development in bivalves.