Ectopic expression and functional research of Apple MdDRB1 gene in tomato

【Objective】To explore ectopic expression and function of the Md DRB1 gene in tomato,Apple Md DRB1 was transformed into tomato plants. 【Methods】Apple Md DRB1 gene was genetically trans-formed into tomato with an Agrobacterium-mediated method. PCR analysis verified that Md DRB1 genewas integrated into the genome of tomato. Three among five transgenic lines with different levels of MdDRB1 transcripts were chosen for RT-PCR analysis concerning the expression levels of auxin-related mi-cro RNAs and their target genes. Meanwhile,the seedlings were treated with IAA and detected for the pho-totropism;【Results】The results indicated that the accumulation levels of 4 auxin-related,i.e. mi R164,mi R160,mi R393 reduced and mi R167 increased with the ectopic expression of Md DRB1 in tomato trans-genic seedlings,while the transcripts of their target genes such as Sl NAC1,Sl ARF10,Sl ARF16,Sl TIR1 increased and Sl ARF8 reduced. As a result,transgenic seedlings generated more lateral roots in responseto IAA treatment than the WT control. Meanwhile,the phototropism of the transgenic seedlings was posi-tively correlated with the expression of Md DRB1 gene in transgenic tomatoes;【Conclusion】Our data indi-cated that the ectopic expression of Md DRB1 gene in tomato repressed the accumulation levels of auxin-related mi RNAs including mi R164,mi R160,mi R393 and increased the expression of mi R167,andtherefore partially relieved or enhanced the post-transcriptional gene silencing of their target genes,finally to change the sensitivity to auxin signal.