Investigate Nature of Resistance and Breed Sugarbeet for Resistance to Sugarbeet Cyst Nematode.

The sugarbeet cyst nematode (SBCN) (Heterodera schachtii Schmidt) is a serious pest of sugarbeet (Beta vulgaris L.) throughout the United States and world.  Until recently, efforts to develop host plant resistance or immunity in sugarbeet focused on transferring resistance to sugarbeet from a terminal translocation on chromosome IX from B. procumbens (section Procumbentes of Beta). B. procumbens is outside the primary genepool of sugarbeet.  Starting in the 1990’s, screening of the USDA-ARS National Plant Germplasm System’s (NPGS) Beta collection has uncovered a number of accessions with tolerance to the SBCN, which provide enough protection to make sugarbeet production economically viable.  At least one tolerant source has been released in commercial germplasm.  More sources are being evaluated in the greenhouse.  Crosses have been made between sugarbeet and seven potential sources of SBCN resistance identified through screening the genetic resources in the NPGS Beta collection.  Twenty-five F₂ populations from six crosses were screened in the greenhouse to identify families suitable for genetic analyses and to advance breeding material for germplasm development.  Seventeen additional sources identified by screening the Beta collection were retested.  Some of the F₂ populations have a wide range of performance when challenged by SBCN with some individuals doing as well as the mean of commercial resistant control.  Individuals (approximately 98 to 150 per population) from six of these F₂ populations are being selfed to produce F₃ families to confirm resistance.  The populations will be mapped to better understand the inheritance of resistance, identify selectable markers linked to the resistance, and increase seed from the resistant families to produce SCBN resistant germplasm.