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 (NO(2)-OA) have relevant physiological roles as signalling molecules also in plants. Although NO(2)-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 NO(2)-OA in its tissues can be assumed. Therefore, we quantified NO(2)-OA in B. napus seeds and differently developed seedlings. In all samples, NO(2)-OA was detectable at nanomolar concentrations. The seeds showed the highest NO(2)-OA content, which decreased during germination. In contrast, nitric oxide (•NO) levels increased in the early stages of germination and seedling growth. Exogenous NO(2)-OA treatment (100 µM, 24 h) of Brassica seeds resulted in significantly increased •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, •NO-sensitive electrode) supported the •NO liberating capacity of NO(2)-OA. We observed for the first time that Brassica seeds and seedlings contain free NO(2)-OA which may be involved in germination as an •NO donor as suggested both by the results of exogenous NO(2)-OA treatment of seeds and in vitro approaches. Due to their high NO(2)-OA content, Brassica sprouts can be considered as a good source of dietary NO(2)-OA intake.