Abstract: Intergenerational inheritance of stress memory plays a crucial role in plant adaptation to environmental changes, particularly in the context of spaceflight, where plants may serve as a food source for humans on long-duration missions. However, the intergenerational genetic effects of spaceflight-induced stress memory in plants remain unclear. In this study, we assessed the cross-generational genetic effects of spaceflight stress memory using the rice mutant strain B10, identified during the SJ-10 return satellite mission. Our results showed that the oxidative stress effects induced by spaceflight persisted until the M5 generation in rice. We found that the rice genome remained unstable post-spaceflight, leading to alterations in genome methylation levels. Additionally, we observed significant changes in the methylation levels of transposons, suggesting their involvement in the intergenerational inheritance of spaceflight-induced stress memory. Furthermore, we identified thousands of differentially expressed genes (DEGs) and differentially alternatively spliced (DAS) genes induced by spaceflight stress memory across multiple rice generations. Notably, differentially methylated cytosines were more abundant in non-expressed genes than in DEGs or DAS genes. A substantial number of DEGs and DASs related to oxidative stress were identified, primarily involved in the generation and scavenging of reactive oxygen species (ROS). This study also presents the first report on the response of alternative splicing (AS) events in rice to spaceflight stress. Moreover, our findings revealed that genome methylation was associated with gene expression but not with DAS. In conclusion, our study provides comprehensive insights into the intergenerational inheritance of spaceflight-induced stress in rice and may contribute to uncovering novel mechanisms of oxidative stress-induced genomic instability and epigenetic regulation in plant stress inheritance.

Key words: DNA methylation, intergenerational inheritance, rice, SJ-10 return satellite, spaceflight, stress memory