Cloning And Expression Analysis Of PbMYBR And Related Genes In Red Skin Mutant Of'zaosu'PEAR

Red pear breeding has been a major topic in pear breeding. The MYB transcription factors are the keyfactors in the regulation of anthocyanin biosynthesis and adversity stress. In this study, we used the red skinmutant of 'Zaosu' pear as the material, which is unique in China. At the basis of constrction of SSH cDNAlibrary, we isolated the PbMYBR gene, and analysis the relative expression of certain transcription factorsand anthocyanin biosynthesis genes in the different development stages of the red and green fruit. What ismore, we also predict and analysis the function of PbMYBR gene. The main results are as follows:1. According to the homologous sequences from other plants, degenerate primers were designed toamplify specific DNA fragment using cDNA prepared from the red skin mutant of 'Zaosu' pear. The1326-bp full-length cDNA of PbMYBR was obtained using RT-PCR and RACE PCR. The predictedprotein of PbMYBR had442amino acids. Alignment of the predicted translations of PbMYBR gene withother MYB TFs at the MYB domain indicated a high degree of homology. Phylogenetic analysis showedthat PbMYBR is in the same cluster with apple MdMYR8, besides PbMYBR has a high degree ofhomology with MYB TFs in Arabidopsis thaliana and Pyrus pyrifolia, these results suggested thatPbMYBR might have the similar function as MYBs, which play an important role in regulatinganthocyanin synthesis.2. According to the homologous sequences from Pyrus pyrifolia, PbF3H gene was cloned from'Zaosu'leves and its red mutant fruits and leaves, sequence analysis showed that F3H genes were highlyconservative.3. Using the Real-time PCR method to compare their relative expression of the transcription factors,PbMYBR and PyMYB10, and anthocyanin biosynthetic genes ANS, DFR, CHI,CHS, F3H genes in'Zaosu'pear and its red skin mutant in six different development stages accordingly. In 'Zaosu' red skinmutant, transcription of PbMYBR in the fruit, leaf, stem and flower buds were investigated. The resultsshowed that the expression of PbMYBR, F3H and CHS is relate to the appearance changes of the red skinmutant of 'Zaosu' pear.4. By isolating the full length cDNA of PbMYBR and linking it to binary vector pWR306with ligases,the pWR306-PbMYBR plant expression vector was constructed, PbMYBR was over expressed in 'Zaosu'leaf. The transgenetic plant was obtained in selection culture medium.