| 20305027 |
Paulin MM, Nicolaisen MH, Sorensen J: Abundance and expression of enantioselective rdpA and sdpA dioxygenase genes during degradation of the racemic herbicide (R,S)-dichlorprop in soil. Appl Environ Microbiol. 2010 Mar 19.
The rdpA and sdpA genes encode two enantioselective alpha-ketoglutarate-dependant dioxygenases catalyzing the initial step of microbial degradation of the chiral herbicide (R,S)-2-(2,4-dichlorophenoxy) propionate (R,S-dichlorprop). Primers were designed to assess abundance and transcription dynamics of rdpA and sdpA genes in a natural agricultural soil. No indigenous rdpA genes were detected, but sdpA genes were present at levels of approximately 10 (3) copies g (-1) of soil. Cloning and sequencing of partial sdpA genes revealed a high diversity within the natural sdpA gene pool that could be divided into four clusters by phylogenetic analysis. BLASTp analysis of deduced amino acids revealed that members of cluster I shared 68-69 % identity, cluster II 78-85 % identity, cluster III 58-64 % identity, and cluster IV 55 % identity to their closest SdpA relative in GenBank. Expression of rdpA and sdpA in Delftia acidovorans MC1 inoculated in soil was monitored by reverse-transcription quantitative real-time PCR (qPCR) during in situ degradation of 2 and 50 mg kg (-1) of (R,S)-dichlorprop. (R,S)-dichlorprop amendment created a clear up-regulation of both rdpA and sdpA gene expression during the active phase of (14) C-labeled (R,S)-dichlorprop mineralization, particularly following the second dose of 50 mg kg (-1) herbicide. Expression of both genes was maintained at a low constitutive level in non-amended soil microcosms. This study is the first to report the presence of indigenous sdpA genes recovered directly from natural soil and also comprises the first investigation into the transcription dynamics of two enantioselective dioxygenase genes during the in situ degradation of the herbicide (R,S)-dichlorprop in soil. |
31(0,1,1,1) |