, Volume 21, Issue 1, pp 88-97
Date: 01 Oct 2011

Analysis of promoter activity of PtDrl02 gene in white poplars

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To determine the transcriptional activity of the promoter of Populus TIR (Toll/interleukin-1 receptor domain)-encoding PtDrl02 gene in perennial plants, β-glucuronidase (GUS) gene expression driven by PtDrl02 promoter was analyzed in white poplars. Agrobacterium-mediated transient expression assays indicated that the PtDrl02 promoter was able to direct the GUS reporter gene transcription in stem tissues of both triploid [(Populus tomentosa × P. bolleana) × P. tomentosa, clone ‘L9’] and diploid (P. tomentosa cv. 1521) white poplars, and that the transcript levels seemed to be comparable to each other. In stably transformed P. tomentosa plants, the PtDrl02 promoter directed-gene (GUS) expression behaved in an aerial-specific manner but with a relatively low level in tissues compared to that of the ACTIN reference. Further investigation revealed that the PtDrl02 promoter activity could be induced by wounding, methyl jasmonate (MeJA), salicylic acid (SA), abscisic acid (ABA), or high salinity (NaCl) in transgenic P. tomentosa but with a time-course manner. Intriguingly, dynamic expression of the GUS reporter gene driven by PtDrl02 promoter, over given time periods, appeared to be similar to that of the native pathogenesis-related (PR) protein gene (PtPR-1, PtPR-5, or PtPR-10) in transgenic P. tomentosa plants when exposed to the same inducers. Here it was also evidenced that the PtWRYK1 transcription factor conferred a negative effect on PtDrl02 promoter functions in white poplars. Our work provided new information on PtDrl02 promoter activity in poplars, which could be helpful to increase our understanding of the transcription regulation of the Populus TIR-encoding gene by its promoter.