Nitro-Oleic Acid in Seeds and Differently Developed Seedlings of Brassica napus L.

Similar to animals, it has recently been proven that nitro-fatty acids such as nitro-linolenic acid and nitro-oleic acid (NO2-OA) have relevant physiological roles as signalling molecules also in plants. Although NO2-OA is of great therapeutic importance, its presence in plants as a free fatty acid has not been observed so far. Since Brassica napus (oilseed rape) is a crop with high oleic acid content, the abundance of NO2-OA in its tissues can be assumed. Therefore, we quantified NO2-OA in B. napus seeds and differently developed seedlings. In all samples, NO2-OA was detectable at nanomolar concentrations. The seeds showed the highest NO2-OA content, which decreased during germination. In contrast, nitric oxide (center dot NO) levels increased in the early stages of germination and seedling growth. Exogenous NO2-OA treatment (100 mu M, 24 h) of Brassica seeds resulted in significantly increased center dot NO level and induced germination capacity compared to untreated seeds. The results of in vitro approaches (4-Amino-5-methylamino-2 ',7 '-difluorofluorescein (DAF-FM) fluorescence, center dot NO-sensitive electrode) supported the center dot NO liberating capacity of NO2-OA. We observed for the first time that Brassica seeds and seedlings contain free NO2-OA which may be involved in germination as an center dot NO donor as suggested both by the results of exogenous NO2-OA treatment of seeds and in vitro approaches. Due to their high NO2-OA content, Brassica sprouts can be considered as a good source of dietary NO2-OA intake.