After three years of studying the canola under field and greenhouse conditions, the scientists were finally able to identify the genes that can become a durable source with multigene resistance to the blackleg disease. Blackleg disease has been a problem in Australia since the 1970s. It is caused by a fungus whose pathogen is highly diverse. On a global scale, blackleg disease remains a threat as well.
According to lead research scientist Dr. Harsh Raman, it is important to continuously seek and discover new sources of major and quantitative resistance in canola to minimize yield loses. Major resistance genes are helpful, but do not offer long-term protection to canola plants because of the blackleg pathogen's ability to mutate and render the major genes ineffective over time. Quantitative resistance, on the other hand, is difficult to select and is complicated by environmental factors. Thus, molecular markers linked with resistant loci could be used to enhance blackleg resistance in canola germplasm.
These new findings can then become the basis for other scientists to produce elite varieties of canola with quantitative resistance, providing canola longer-lasting protection against the blackleg disease.
Figure 4 Genetic and physical localization of Rlm9 locus for resistance to L. maculans in a doubled haploid population from Darmor-bzh/Yudal. Physical map positions are based on the reference genome assembly of Darmor-bzh (Chalhoub et al., 2014). Markers that showed highly significant association with resistance to PHW1223 isolate (AvrLm9) at both seedling and adult plants stages are in bold letters. For clarity, both partial genetic (in cM) and physical maps of chromosome A07 are shown herein; physical locations are depicted as 1/100,000th from the original coordinates.