Academic Year: 2012-2013
Name: Neal Stewart      
Department: Plant Sciences
UTIA Appointment:
Student: Chelsea Johnson
Student Department: Plant Sciences, Biotechnology Concentration
Title of Student Project: Molecular Characterization of Herbicide Resistance in Horseweed (Conyza candensis L.)
Presentations: Winner in the 2013 EUReCA competition for CASNR
Other Products: Poster for the EUReCA competition in March 2013
Abstract of Student Project (when Completed):
Conyza candensis (L.), commonly known as horseweed, is an annual plant native to Northern and Central parts of America. It is one of the first weed plants known to evolve resistance to herbicide (glyphosate). The increase in resistance to glyphosate in horseweed has been a major problem in modern agriculture. Despite this challenge, there is little information on the molecular diversity, as well as possible non-target resistance mechanisms in horseweed. In order to understand genetic relatedness and maternal haplotype diversity, if any, among the glyphosate resistant and/or susceptible horseweed samples, a chloroplast-DNA diversity study has been carried out. The glyphosate resistant and/or susceptible horseweed samples were obtained from different geographical locations, viz., Indiana, Delaware, Tennessee, and California in the United States. Using various chloroplast gene specific molecular markers, the above samples were PCR amplified and gel electrophoresed. The gene products were successfully gel purified and subsequently sequenced at the University of Tennessee-Core Sequencing Facility. The chloroplast nucleotide sequences were analyzed to study the nucleotide diversity and relatedness among the resistant and/or susceptible horseweed samples. The information collected from this study will be directly beneficial for the further weed management strategies.

C. Johnson.JPG
Student: Chelsea Johnson

Mentor: Neal Stewart