Abstract:The fulllength cDNA sequence of metallothionein gene (BcMT2) was cloned from the leaves of nonheading Chinese cabbage disease resistant cultivar ‘Suzhouqing’ by race technique. qRTPCR was used to analyze the expression pattern of this gene in different tissues under biotic stress (P. parasitica) and abiotic stress (salt, drought, ABA) treatment conditions. SDSPAGE technology was used for analysis of prokaryotic expression characteristics for this gene. Sequence analysis showed that the fulllength cDNA of BcMT2 gene was 528 bp. The length of the open reading frame was 243 bp and encoded a total of 80 amino acids. The relative molecular mass was 8.02×103 Da, and the theoretical isoelectric point was 4.61. The phylogenetic analysis of amino acid homology showed that the nonheading Chinese cabbage BcMT2 gene was belonged to the MT2 gene family of class Ⅱ plants and had similar evolutionary relationship with other plants of the same family. Among of them, the gene had the highest homology (100%), comparing with the gene (Bra029765) on A05 in Chinese cabbage. Quantitative realtime analysis showed that the expression of BcMT2 gene was the strongest in leaves of nonheading Chinese cabbage. The expression of BcMT2 gene was peaked at 48 h after infection by Pseudoperonospora cubensis in the diseaseresistant variety ‘Suzhouqing’, while the expression level was peaked at 72 h in the susceptible variety ‘Aijiaohuang’. Under salt treatment condition, the expression level of BcMT2 gene was peaked at 12 h in the resistant variety ‘Suzhouqing’, while the expression level was peaked at 24 h in the susceptible variety ‘Aijiaohuang’. Under ABA treatment, the expression level was peaked at 24 h in ‘Suzhouqing’, and the expression tendency of BcMT2 gene in ‘Aijiaohuang’ was similar to that of ‘Suzhouqing’. The expression of BcMT2 gene was inhibited in both materials under drought treatment conditions. Analysis of BcMT2 prokaryotic expression revealed that a specific molecular band of about 8×103 Da was detected at 2, 4, and 6 h after induction at 37 ℃ and 1.0 mmol·L-1 IPTG, which is related to the expected fusion protein. Results showed that nonheading cabbage BcMT2 gene plays an important role in the stress environment such as biotic stress and abiotic stress. In this study, BcMT2 has successfully achieved fused expression in Bacillus coli. The results established the foundation for the next step in the study of protein levels and the study of transgenic functions. Moreover, it will also provide important theoretical basis for breeding new nonheading cabbage varieties with high yield and good quality.