Cloning and expression analysis of MbACO2 gene in Musa ABB group, cv Pisang Awak, FJ

【Objective】To clone 1-aminocyclopropane-1-carboxylic acid(ACC) oxidase(ACO) gene(MbACO2) from Musa ABB group, cv Pisang Awak, FJ, and analyze its bioinformatics and expression, so as to provide reference for studying the function of ACO gene family in banana fruit ripening and stress process, and to provide potential gene resources for improving banana postharvest storage.【Method】Gene MbACO2 was cloned from Musa ABB group, cv Pisang Awak, FJ by RT-PCR.The physicochemical properties, hydrophilicity/hydrophobicity, conserved domains and secondary/tertiary structures of the encoded protein were predicted by bioinformatics analysis.Subcellular localization was conducted using Agrobacterium-mediated transient transformation.The expression level of MbACO2 gene in fruit development and stress response(high-salt, drought and low temperature) was detected by real-time quantitative PCR.【Result】The open reading frame(ORF) length of MbACO2 was 918 bp, encoding 305 amino acid residues.The molecular weight of the protein was 34.583 kD and the theoretical isoelectric point(pI) was 5.43.The protein encoded by MbACO2 gene belonged to hydrophilic protein, which had typical plant ACO structural characteristics and contained two conservative domainsDIOX_N and 2OG-FeⅡ_Oxy.The amino acid sequence of MbACO2 was similar to that of ACO amino acid sequence(XP_010908825.1) in banana(Musa acuminata AAA group) and the similarity reached 98.04%, indicating that the amino acid sequence of MbACO2 protein was highly conserved.The subcellular localization results showed that MbACO2 protein was expressed in both nucleus and cytoplasm.The expression of MbACO2 gene increased with the development of fruit ripening, and was extremely higher than 0 d after flowering(control) (P< 0.01, the same below).The expression level of MbACO2 was the highest 6 d after harvest.Under high-salt, drought and low temperature, the relative expression of MbACO2 gene was significantly up-regulated(P< 0.05) or extremely up-regulated compared with control(no stress treatment).【Conclusion】MbACO2 gene belongs to ACO gene family, it contains the typical domains of the family, and it playsa positive regulation role in banana fruit ripening and stress resistance of Musa ABB group, cv Pisang Awak, FJ.High-salt, drought and low temperature can induce its upregulation of expression.