Location: Sunflower and Plant Biology Research
Project Number: 3060-21000-043-08-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2017
End Date: Jun 30, 2021
1. Identify novel QTL associated with Sclerotinia BSR resistance in an advanced backcross population (AB-pop1) derived from the cross of HA 89 and wild annual species H. petiolaris PI 435843. 2. Identify novel QTL associated with Sclerotinia BSR resistance in AB-pop2 derived from the cross of HA 89 and wild annual species H. praecox PI 468853. 3. Identify novel QTL associated with Sclerotinia BSR resistance in AB-pop3 derived from the cross of HA 89 and wild annual species H. argophyllus PI 494573. 4. Develop F2 populations combining existing and novel QTL (from this study) to investigate the phenotypic interaction conferring partial resistance to BSR in sunflower.
For BSR resistance QTL identification, we have developed three advanced backcross (AB) populations by crossing the inbred line HA 89 with three sunflower wild species, H. petiolaris, H. praecox, and H. argophyllus as resistant donors. Each AB population will be assayed separately for response to Sclerotinia BSR infection in replicated field trials using artificial inoculation over 3-year period (2017-2019). Phenotypic disease reaction data from field trials will be collected across locations and years. The second step for QTL analysis will be to genotype the individual lines in the mapping populations and develop molecular linkage map for each AB population. The individual lines of each population will be genotyped using genotyping-by-sequencing (GBS) approach for simultaneous discovery of single nucleotide polymorphism (SNP) markers. SNP markers associated with QTL conditioning resistance to BSR as measured in the field will be detected using QTL analysis software. In addition, the two highly dense SNP genetic maps containing more than 15,000 markers have been developed in sunflower in the past few years, which can be used to further saturate the QTL region associated with Sclerotinia BSR resistance and better define the genomic position of QTL. SNP markers associated with QTL could potentially provide an aid to conventional breeding in introgressing complex traits during inbred development. BSR resistance QTL identified previously in cultivated sunflower and the novel QTL expected to be detected from these studies will be pyramided into various genetic combinations to examine QTL interactions. Crosses will be made using germplasms possessing QTL from cultivated sunflower and wild H. petiolaris, H. praecox, and H. argophyllus species. The F1 hybrids will be tested in the greenhouse under control conditions. The selected F1 resistant plants will be advanced to F2 generations. This proposal addresses the Goal 1 of the Sclerotinia Initiative Strategic Plan: Germplasm Resources and Translational Genomics.