Unveiling the Impact of Vernalisation on Seed Oil Content and Fatty Acid Composition in Rapeseed (Brassica napus L.) Through Simulated Shorter Winters

Abstract

Climate change is leading to warmer winters world-wide with an increasing number of extreme events every year. Studies show that winter varieties of rapeseed are particularly impacted negatively by global warming. This study investigates the molecular, physiological, and biochemical effects of diverse vernalisation scenarios (i.e., the vernalisation models) on rapeseed plants and seeds. The winter and spring varieties of rapeseed (Brassica napus L.) were subjected to short durations of vernalisation (3 and 4 weeks) as well as to 6- and 8-week long vernalisation interrupted by 1-week devernalisation intervals at warm temperatures. Our results reveal a notable difference in vernalisation responsiveness in major floral regulator FLC orthologues between the late-flowering winter variety, Darmor, the early-flowering winter variety, Bristol, and the spring variety, Helios, after 3 weeks of vernalisation. Within the three FLC genes (BnaFLCA02, BnaFLCA10, and BnaFLCC02) analysed in this study, BnaFLCA10 emerged as the most responsive to vernalisation in all three varieties. The vernalisation duration significantly influenced seed oil content and fatty acid composition in both Bristol and Helios varieties. In Bristol, the 2 + 6w vernalisation model in which vernalisation was interrupted for 1 week after 2 weeks of vernalisation and continued for another 4 weeks consistently resulted in the highest oil content and oleic acid percentage. The interrupted vernalisation (2 + 4w and 2 + 6w) also led to increased monounsaturated fatty acids across all 3 years. In Helios, non-vernalised plants produced seeds with the lowest oil content, and vernalisation duration positively correlated with both seed oil content and oleic acid percentage. Our findings unveil a robust correlation between vernalisation and seed oil content, as well as fatty acid composition in rapeseed.