Sequential cold and heat stresses establish an intergenerational stress memory in rapeseed (Brassica napus L.)

Abstract

Plants frequently experience temperature extremes that threaten growth and reproduction, yet their ability to retain and transmit stress responses across generations remains poorly understood. In this study, we investigated whether early cold exposure primes rapeseed seedlings for enhanced heat tolerance and whether such effects are inherited by the next generation. Seedlings were subjected to cold stress (4 {degrees}C for 3 weeks), heat stress (38 {degrees}C for 2 days), or sequential cold followed by heat stress. Control plants were grown under optimal conditions. We evaluated physiological, biochemical, and molecular traits in both the treated plants and their first-generation progeny. Temperature stress influenced flowering time, seed weight, seed oil content, and fatty acid composition. Genes involved in fatty acid metabolism, including BnaFAD2, BnaFAD5, BnaFATB, and BnaWD40, were differentially expressed. In the progeny of sequentially stressed plants, total phenolics, flavonoids, antioxidant activity, and chlorophyll content were significantly elevated, indicating the presence of intergenerational stress memory. Our findings show that sequential cold-heat stress not only enhances immediate stress tolerance but also induces heritable metabolic and physiological adaptations. These results provide new insights into the mechanisms of cross-tolerance and the potential for exploiting intergenerational stress memory in crop improvement.