Combined treatment of epi-brassinolide and NaCl enhances the main phytochemicals in Chinese kale sprouts

•NaCl treatment alone or combined with eBL improved the content of glucosinolates.•Combined treatment of eBL and NaCl enhanced ascorbic acid content.•Combined treatment of eBL and NaCl attributed to the increase of carotenoid content.•The expression of MYB transcription factors was activated by the eBL and salt stress.