Location: Sunflower and Plant Biology Research2012 Annual Report
1a. Objectives (from AD-416):
Development and evaulation of non herbicide-tolerant B. napus breeding populations using recently discovered sources of resistance and identify Brassica napus gerbicide-tolerant breeding lines with enhanced resistance to Sclerotinia sclerotiorum.
1b. Approach (from AD-416):
This proposal builds on results of previous projects that identified B. napus and B. rapa plant introduction materials and developed double haploid lines from Ames 26628, a B. napus accession with high levels of resistance to S. sclerotiorum. The project described here intends to develop and evaluate canola breeding populations using Ames 26628 DH lines and to continue efforts to identify herbicide-tolerant canola breeding lines with enhance resistance to S. sclerotiorum within the NDSU canola breeding program. To develop the breeding population, we intend to first produce DH materials from Topas, a public line which has been selected to be the susceptible parental line. F2 seeds from the Ames 26628 x Topas cross will be screened in the greenhouse using the petiole inoculation technique. Plant samples will be collected at this time for molecular marker evaluation. Resistant materials will be taken to seed production in the greenhouse and the following summer they will be evaluated in a disease nursery for their reaction to S. sclerotiorum as well as for agronomic traits. The identification of herbicidetolerant canola breeding lines with resistance to S. sclerotiorum will be conducted through replicated greenhouse and field trials. This project would contribute towards one of the goals of the Sclerotinia Initiative: the identification and characterization of new sources of resistance to manage diseases caused by this pathogen.
3. Progress Report:
This project was initiated on July 1, 2010, research is ongoing, and the overall objective is the development of canola breeding populations and identification of herbicide-tolerant breeding lines with resistance to Sclerotinia sclerotiorum. Projects previously funded by the Sclerotinia Initiative identified Brassica napus plant introductions with higher resistance to S. sclerotiorum than the commercial cultivars used as controls. These materials were crossed to develop breeding populations, one conventional and the other a doubled haploid (DH). The conventional population was developed from the cross between Ames 26628 and PI458939, the DH population was created from the cross between Ames 26628 and PI458940. During the last two years, we challenged seedlings from the Ames 26628xPI458939 population using the petiole inoculation technique, allowed the survivors to produce seed, and then screened their descendants. Using this selection procedure we advanced surviving plants from this population to the F6 generation. With each new generation plants became more tolerant of infection and those plants that died took longer and longer to do so. The percentage of surviving plants increased from 30% in the F1 to 85% in the F4 generation. We are currently increasing seeds from materials that survived the last inoculations to evaluate them in the fields as part of the activities outlined in this proposal. The DH population was also screened using the petiole inoculation technique, and a DH line, NEP63, was identified as having the highest levels of resistance. We are currently increasing seed of this DH line for field testing.Glyphosate-tolerant canola breeding lines were identified as having statistically less disease than the commercial controls included in the study. In 2011, Sclerotinia stem rot (SSR) incidence ranged between 3% and 40% although most lines evaluated had <25% incidence. Seven breeding lines had SSR incidences below 15%. Some of these lines have performed well in previous years and have been advanced to the next level by the breeder.