Analysis of the Interaction between PeMADS6 Transcription Factor and Pathogenesis-Related Genes in Phalaenopsis Orchids
Date Issued
2009
Date
2009
Author(s)
Hsu, Hwa-Fang
Abstract
Generally, plant is more susceptible during seedling stage and gradually become more resistance to pathogen infection. This type of resistance is named developmental resistance. Several transcription factors are reported to be involved in plant development. The most known transcription factors that involved in plant development belong to the MADS-box gene family. In our previous study, we knockdowned a Phalaenopsis orchid MADS-box gene, PeMADS6, in Phalaenopsis amabilis by Cymbidium mosaic virus- (CymMV) induced gene silencing vector for functional analysis. Accidentially, we found the accumulation of CymMV coat protein (CP) gene was greatly increased in PeMADS6 silenced floral organ. We speculated that PeMADS6 may involve in the Phalaenopsis orchid developmental resistance. To explore the possibility, we identified pathogen-related (PR) genes from orchid EST library, and analyzed the PR genes expression in response to PeMADS6 expression. We found that PR1 and PR10 can be induced by CymMV both in leaves and flowers; however, both PR1 and PR10 can not be induced in PeMADS6 silenced flowers. In addition, PR7 can be induced by CymMV in leaves but not flowers, and PR16 can be induced by CymMV both in leaves and flowers regardless the expression of PeMADS6. To further analyze if the PeMADS6 involved in the regulation of PR genes, we extended the upstream region of these PR genes by genome walking and analyzed the cis-acting elements in those regions. Notably, 7 CArG motifs were found in the upstream region of PR1 but not in PR10. Protein-DNA binding assay was conducted to assay wheather PeMADS6 can directly bind the upstream region of PR1. The results indicate that PeMADS6 can directly bind to upstream region of PR1 but not PR10, and suggeste that PeMADS6 may regulate PR1 in a directly mannor and PR10 in an indirectly mannor.
Subjects
Developmental resistance
Pathogenesis-Related (PR)gene
promoter analysis
DAPA (DNA Affinty Protein Binding assay)
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