The evolutionary impact of a Pack-MULE element in tomato and its wild relatives
Pack-Mules have been identified in several plant species. In tomato there are 250 Pack-MULEs. Among which, a Pack-MULE with 50 copies (SlMP37) has been found, which is uncommon for Pack-MULEs, suggesting selection for it being maintained in Solanum lycopersicum and wild relatives. SlMP37 contains captured fragments of two parental genes: Argonaute 1(AGO1) and Cytochrome P450 (CYP51). AGO1 codes for an RNA Slicer protein that is an essential component of the RNA-induced silencing complex (RISC) and its function in RNA silencing. CYP51 is an enzyme which is required for sterol biosynthesis in plants and other organisms. To test the effects of SlMP37, several DNA constructs were transformed into S. lycopersium containing a marker gene under the control of the promoter of the parental genes. The portion of the parental genes that has been duplicated by the Pack-MULE was concatenated to the marker gene to test its impact, with the non-duplicated regions as a control. Confirmation of the construct was determined through Southern blot tests. A kanamycin probe was used to detect the presence of DNA complimentary to the constructs. Characterization of the plants was done through phenotyping of tomato fruit yield, seed weight, and plant height.
