Expression Pattern Of The MdACO1and MdHB-1in Apple，and The Construction Of Erpression Vector Of MdHB-1Together With Its Transformation Into Tomato

In this study, we investigated the expression level of MdACO1and its transcription factorMdHB-1in different organs and different developmental stages to revealing their expressionpatterns with the apple cultivar ‘Royal Gala’ as the materials. Furthermore, we identified theresponse of these two genes to exogenous ethylene to explore the possible interaction betweenthem, which could provide useful information to further reveal the regulatory mechanism ofethylene biosynthesis and the molecular mechanisms of apple ripening. Additionally, we alsotransferred the MdHB-1gene to Micro-tom tomato by Agrobacterium-mediated transgenicmethod to clarify its role in regulating MdACO1expression as well as other biologicalfunctions. The main results of this study were listed as follows:1. In various tissues and organs, the MdHB-1was observed to be expressed in petals withhigher levels by real-time quantitative PCR analysis, while MdACO1expressed higher inmature fruit. It’s postulated that MdHB-1may be involved in the regulation of the expressionof related genes in young apple fruit and floral organs, while the MdACO1seems not beinvolved in this process.2.In different development stages, the MdHB-1have the highest expression in immaturefruit (40d after flowering), while MdACO1showed highest expression in the mature fruit, inparticular at100d after flowering. MdACO1is involved in the maturation of the apple fruit,but it was not controlled by MdHB-1.3. We further investigated the expression level of MdACO1and MdHB-1in applefruit(110d after flowering) treated with exogenous ethylene (500mg/L), results showed thatwhen treated for0-1d, the expression of MdHB-1was inhibited, but the expression level ofMdHB-1increase significantly after7days. The expression of MdACO1increased rapidlywhen exogenous ethylene treatment, and greatly increase with the extension of storage time.It suggested that exogenous ethylene could induce the overexpression of MdACO1in applefruit, while the feedback regulation process seemed to be MdHB-1independent.4. We further constructed the overexpression vector pBI121-2A11-MdHB-1, and verfified the construction by colony PCR and restriction enzyme digestion.5. Finally, the recombinant expression vector was transferred into Micro-tom tomato byAgrobacterium-mediated method. After screened by PCR, a total of4transgenic plants wereobtained, which provided the valuable resource for biological function studies of MdHB-1.