A rapid method for partial mRNA and DNA sequence analysis of the photosystem IIpsbA gene

Single amino acid substitutions in the D1 protein of photosystem II may cause resistance to various herbicides. In all organisms studied these substitutions are located in or between helices IV and V of the protein. The increasing number of herbicide-resistant organisms necessitates development of a rapid methodology to characterize deviations from the wildtype sequence. Here, two procedures are described to identify mutations in the psbA gene, which is coding for D1. These procedures involve the isolation and amplification of DNA and RNA and subsequent sequencing reactions without the need to clone the psbA gene. A triazine-resistant and a -susceptible biotype of Chenopodium album were used as model species. An A to G transition, giving rise to a serine to glycine mutation at position 264 in the D1 protein, is found in the resistant plant.