The role of ethylene regulator MaACO2 interacting proteins in fruit ripening using nuclear yeast cDNA technology in banana

• MaACO2 gene is a homologous gene of ACC oxidase genes in banana genome, involving fruit ripening. • A nuclear yeast library at the 3rd stage of fruit maturity was constructed. • The 28 and 40 proteins were respectively identified by yeast Two-Hybrid and One-Hybrid techniques, and the interaction between NAC21/22 and RING-H2 zinc finger protein ATL2 with MaACO2 by reverse validation. • Expressions of glucan endo-1,3-β-glucosidase, ATL2 and NAC21/22 were significantly increased at the 3 rd stage of fruit maturity, and the chitinase 1 was increased at the 4 th stage. • Ethylene and 1-MCP promote and inhibit the expression of MaACO2 interacting protein coding genes, respectively. Among 18 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase homologous genes existing in the banana genome there is a gene, MaACO2 , that participates in banana fruit ripening. We constructed a banana nuclear yeast library and identified the transcriptional and post-translational proteins interacting with MaACO2 by One-Hybrid and Two-Hybrid techniques. Twenty-eight proteins interacting with MaACO2 were screened by yeast Two-Hybrid. The interactions of chitinase 1 and glucan endo-1,3-β-glucosidase with MaACO2 were verified by point-to-point reverse validation. Additionally, the 40 proteins were identified by yeast One-Hybrid, and the interactions of NAC21/22 and RING-H2 zinc finger protein ATL2 with MaACO2 promoter were also confirmed by reverse validation. The expression levels of glucan endo-1,3-β-glucosidase, ATL2 and NAC21/22 , were significantly increased at the 3 rd stage of fruit maturity when the peel color was greener but not yellow. However, the expression of chitinase 1 was significantly increased at the 4 th stage of fruit maturity and the pericarp color was more yellow but not green, and then the gene expression gradually decreased. Ethylene and 1-MCP promote and inhibit the expression of MaACO2 interacting protein coding genes, respectively.