Location: Soil Management and Sugarbeet ResearchTitle: Beet curly top resistance in USDA-ARS pre-breeding germplasm, 2021
Submitted to: Plant Disease Management Reports
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2022
Publication Date: 8/9/2022
Citation: Dorn, K.M., Strausbaugh, C.A., Galewski, P.J. 2022. Beet curly top resistance in USDA-ARS pre-breeding germplasm, 2021. Plant Disease Management Reports. 16. Article eV165.
Interpretive Summary: Beet Curly Top remains an perpetual challenge for sugar beet growers, mainly in the western United States. Utilizing a panel of sugar beet germplasm developed by USDA scientists over the past half century, Agricultural Research Service scientists in Fort Collins, CO and Kimberly, ID screened sugar beet lines for resistance to Beet Curly Top Virus. The researchers identified 8 germplasm lines with Beet Curly Top Virus resistance equivalent to the highly resistant commercial check line. These USDA-ARS pre-breeding lines represent potential starting material for identifying genes responsible for Beet Curly Top resistance, as well as the long term goal of diversifying forms of genetic resistance to Beet Curly Top in elite hybrids used by growers.
Technical Abstract: Thirty sugar beet (Beta vulgaris L.) germplasm lines produced by USDA-ARS pre-breeding programs and three commercial check cultivars were screened for resistance to Beet curly top virus (BCTV). The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID. The plots were two rows 10-ft long with 22-in. row spacing and treatments were arranged in a randomized complete block design with six replications. Plants were inoculated at the four- to six-leaf growth stage on 22 Jun with approximately six viruliferous (containing the following BCTV strains: California/Logan and Severe) beet leafhoppers (Circulifer tenellus Baker) per plant. The beet leafhoppers were redistributed two times a day during the first seven days by dragging a tarp through the field. The plants were sprayed with Lorsban 4E on 6 Jul to kill the beet leafhoppers. Plots were rated for foliar symptom development on 12 Jul using a scale of 0 to 9 (0 = healthy and 9 = dead), with the scale treated as a continuous variable. Data were rank transformed prior to analysis in SAS with mixed linear models (Proc MIXED), but the non-transformed means have been presented in the table. Mean separation was based on a PDIFF comparison with a probability cutoff of 0.05. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The resistant and susceptible checks performed as expected for the visual ratings. Statistically, 17 of the entries had visual ratings significantly lower than those for both susceptible checks, indicating these genotypes had at least minor levels of resistance. However, eight entries (FC220xF1024, C869, EL44, C842, FC607, FC1019, CS42, and EL54) had resistance levels that were not significantly different than the commercial resistant check. A majority (22 of 30) of the entries in this panel are a part of a USDA-ARS whole genome resequencing project. These eight entries along with entries with similar levels of resistance will be retested and, if resistance is confirmed, these lines will be used to map BCTV resistance gene(s) present in these genotypes and used as sources of BCTV resistance in USDA-ARS germplasm improvement programs.