Cloning Of Apple And Pear Of Ferritin Gene And Expressing Characteristics Of Bean Ferritin Gene In Transgenic Apple And Tomato Plants

Ferritins (iron-binding protein) are ubiquitous iron storage proteins that are present in plants, animals and micro-organisms. Ferritins are a class of large protein shells composed of 24 subunits that store up to 4500 iron atoms in a soluble, non-toxic and bioavailable form. Ferritins play a key role in cellular iron homoeostasis.Apple is an important fruit tree planted widely in the world. Until now studies on cloning and expressing characteristics of ferritin gene of apple are poor. In this study, we carried out some works: cloning of ferritin genes and promoters from apple and pear, expressing characteristics of ferritin genes in the genomes of transgenic and non-transgenic apple plants, studying effect factors on expressing of exogenous ferritin gene in the genomes of transgenic apple plants, presuming on expressing of exogenous ferritin gene in the genomes of transgenic apple plants based on the transgenic tomato plants.1. A full cDNA sequence of ferritin gene was cloned from leaves of Malus domestica Borkh. cv 'Gala' by RT-PCR and RACE methods. It was named MdFer, and the accession number in GenBank is DQ099429. The fragment is 1043bp with 831bp open reading frame of 277 amino acids, a 209bp non-coding 3'region after the stop codons. The predicted amino acids sequence of MdFer shows 85% identity to Glycine max, 83% to Vigna unguiculata, 82% to Arabidopsis thaliana, 80% to Nicotiana tabacum, 75% to Malus xiaojinensis, 74% to Brassica napus, 72% to Oryza sativa, and 71% to Zea mays, respectively. Southern blottmg analysis shows the existence of seven copies of ferritin gne at least in the genome of Malus domestica Borkh. After treatment with 0.5mM iron-citrate, the expression level of MdFer increased gradually with induced time, the results indicated that the expression of MdFer was regulated in response to iron at transcriptional level. The MdFer promoter region was cloned from Malus domestica Borkh. cv 'Gala' by promoter walking method, containing G-box, Block II, SHS sequences that were conserved regions in other ferritin genes. The IDRS (iron-dependent regulation sequences) region of MdFer promoter was a higher identity to that of the ZmFer promoter at position -83—70bp.2. The four full cDNA sequences of ferritin genes were cloned from leaves of Pyrus pyrifolia Nakai.cv'Cuiguan' by RT-PCR and RACE methods. They were named PpFerl,...