Abstract:

Apple dwarfing rootstock M9 and vigorous rootstock MM106 were used as the material to clone a 3 753 bp nucleotide sequence encoding a length of 1 250 amino acids. The fragment named as MdABCB19 because of high homology with apple（XP 008341564.1），pears（XP 009347047.1），rape（XP 009151836.1），and Arabidopsis（AT3G28860.1）protein sequence of ABCB19. MdABCB19 sequence in M9 and MM106 presented of non-synonymous SNP，leading to the amino acid sequence different at the 885th amino acids：M9 serine（Ser），MM106 alanine（Ala）. Protein structure analysis found that the amino acid point mutations，leading to a shorter alpha helix in M9. Real time quantitative expression analysis showed that，MdABCB19 were differentially expressed in the rootstock M9 and MM106 MdABCB19 were also cloned and found“CTCTGT”6 bp deletion at about the 170 bp upstream of the start codon of M9 MdABCB19 promoter，resulting in missing a 5'UTR Py-rich stretch motif. Promoter cis element analysis shown MdABCB19 promoter region contained several light response motifs. Promoter GUS staining shown that MM106 MdABCB19 promoter activity was higher than M9. The MdABCB19 promoter wereregulated by light. M9 MdABCB19 pro-actingmoter 5'UTR Py-rich stretch motif deletions may induce in MdABCB19 low expression in M9.

Key words: apple, auxin, MdABCB19, rootstock, dwarfing