Location: Sunflower and Plant Biology Research2011 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. ADODR monitoring activities to evaluate research progress included phone calls, meetings with the cooperator, and an annual meeting held each year in January. We evaluated herbicide-tolerant advanced canola breeding lines under field conditions for their reaction to Sclerotinia stem rot. Plots were inoculated twice with an ascosporic suspension (103 ascospores ml"1) and misted to stimulate disease development. Disease incidence ranged between 3 and 81% and severity between 0.3 and 3.6 (0-5 scale). Average incidence and severity for lines, 9023, 9024, 9091, and 9092 was 12% and 0.3, respectively. In contrast, the average incidence of the four commercial controls used in this study was 28% with a mean severity of 1.1. These lines are being advanced in the breeding program. A total of 144 Fa plants from the PI 169080 x Westar population were evaluated in replicated trials for their reaction to S. sderotiorum in greenhouse. Forty six plants produced a resistant reaction whereas 98 were considered susceptible. DNA from these plants has been extracted and sent for genotyping using Diversity Array Technology (DArT). The use of this technology will allow us to screen the materials with more than 3,200 markers and to locate them in a chromosome map. This will facilitate in great deal the identification of QTL associated with resistance. DNA from 282 B. napus accessions was extracted after the seedlings were evaluated for their reaction to S. sderotiorum using the petiole inoculation technique (PIT). Approximately one half of these accessions had been already identified as having some degree of resistance against S. sderotiorum in a previous project funded by the SI (Khot, 2006). DNA from these samples was genotyped using more than 3,200 DArT markers. While more than 1,200 polymorphic markers were detected, data analysis has not been finished yet. Resistant plants from this population have been self-pollinated. We intend to continue evaluation of these materials in the future. The development of double haploid lines from cultivar Topaz was delayed due to problems with contamination of lab media earlier in the year, DH lines from Topaz has resumed. Approximately 288 clones from a DH line produced by the cross between 458940 x Ames 26628 were developed. These two parental lines had been previously identified as resistant to S. sderotiorum. Clones were inoculated using six different methods and using two S. sderotiorum isolates, and petiole inoculation was the most reliable and consistent in detecting differences in resistance as well as differences between the isolates used. A similar study was conducted using DH lines derived from cv. Westar.