Abstract: In this study, Brassica napus L. hairy roots were used to construct an Agrobacterium rhizogenes-mediated heterologous expression system for the sweet protein mabinlin II (M12) from the endangered plant Capparis masaikai Levl. The M12-encoding gene was ligated into the plasmid pCAMBIA to obtain the recombinant vector pCAMBIA-M12, which was then transferred into B. napus L. hairy roots via Agrobacterium-mediated transformation. The successful construction of the expression system was confirmed by β-glucuronidase (GUS) histochemical staining and polymerase chain reaction (PCR). The transformed hairy roots were cultured in liquid medium at 25 ℃ and 150 r/min for one week. The culture was centrifuged, and the precipitate was collected and disrupted. The supernatant was collected as crude extract of M12. Double-blind sensory evaluation and an electronic tongue were used to assess the properties of the crude extract, with a maximum sweetness intensity of 4.89. This study provides a new method for the efficient synthesis of sweet proteins in plant cells and offers a novel approach for the sustainable development of endangered plant resources.

Key words: Capparis masaikai Levl; mabinlin II; heterologous expression in Brassica napus L.; high-efficiency synthesis