An Efficient and Economical Protocol for Isolating, Purifying and PEG-Mediated Transient Gene Expression of Chinese Kale Hypocotyl Protoplasts

In this study, we report the isolation and purification of protoplasts from Chinese kale (Brassica oleracea var. alboglabra) hypocotyls, and their transient gene expression transformation and subcellular localization of BaMYB75 (Bol042409). The upshot is that the vintage protocol included 5-d hypocotyls that were enzymatically hydrolyzed for 8 h in enzyme solution (3.0% cellulase, 0.5% pectolase, and 0.5 M mannitol), and the protoplasts were purified by precipitation. The total yield of protoplasts was 8 × 105 protoplast g−1 fresh weight, and the protoplasts’ viability was 90%. The maximum transformation efficiency obtained by using green fluorescent protein (GFP) as a detection gene was approximately 45% when the polyethylene glycol (PEG)4000 concentration was 40% and transformation time was 20 min. In addition, BaMYB75 was ultimately localized in the nucleus of Chinese kale hypocotyl protoplasts, verifying the validity and reliability of this transient transformation system. An effective and economical hypocotyl protoplast isolation, purification, and transformation system was established for Chinese kale in this study. This effectively avoided interference of chloroplast autofluorescence compared to using mesophyll cells, laying the foundation for future research in the molecular biology of Brassica vegetables.