Submitted to: American Phytopathology Society
Publication Type: Abstract only
Publication Acceptance Date: 6/1/2005
Publication Date: 6/1/2005
Citation: Jackson, E.W., Avant, J.B., Overturf, K.E., Bonman, J.M. 2005. Development of a real-time polymerase chain reaction assay to quantify puccinia coronata f.sp. avenae in avena sativa. American Phytopathology Society. 95 (6):S47 Interpretive Summary: To improve selection of oat genotypes with partial resistance to crown rust caused by Puccinia coronata f.sp. avenae we developed a molecular based assay. The assay uses new molecular tools to accurately estimate the amount of fungal tissue present in infected oat leaves. Using this assay we were able to improve identification of resistant and partially resistant genotypes compared to conventional methods. This assay provides an effective tool to develop new cultivars with enhanced crown rust resistance.
Technical Abstract: Crown rust, caused by Puccinia coronata f.sp. avenae, is the most damaging disease of oat worldwide. Control of crown rust using major resistance (r) genes has not been long-lasting. Partial resistance, where the pathogen infects the host but has decreased growth, may provide greater durability. Quantifying partial resistance to rust pathogens requires either detailed measurements of disease resistance components on individual plants or polycyclic tests on plant populations in field plots. As an alternative to these tedious and time-consuming methods, a real-time PCR assay was developed to accurately measure pathogen development within the host. Taq Man® primers and probe designed to detect P. coronata f.sp. avenae were evaluated. The primers and probe were specific and, by using a set of known standards, we reproducibly estimated fungal dry weight within the host. Image analyses of genotypes with varying levels of crown rust resistance were compared to real-time PCR assays. Real-time PCR was more consistent and sensitive for identifying differences among genotypes. Tests are in progress to ascertain if differences can be detected before disease signs appear. The real-time PCR assay is an accurate and efficient tool to quantitatively measure disease resistance and will be useful for identifying partial resistance to crown rust.