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United States Department of Agriculture

Agricultural Research Service

Research Project: Multidisciplinary Approaches to Enhanced Sugar Beet Germplasm

Location: Sugarbeet Research

Title: Resistance to curly top of sugar beet in germplasm developed at USDA-ARS Ft. Collins, 2013

Authors
item Panella, Leonard
item Strausbaugh, Carl

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2014
Publication Date: August 12, 2014
Citation: Panella, L.W., Strausbaugh, C.A. 2014. Resistance to curly top of sugar beet in germplasm developed at USDA-ARS Ft. Collins, 2013. Plant Disease Management Reports. 8:FC246.

Interpretive Summary: Seventy-one sugar beet lines from the USDA-ARS Fort Collins sugar beet program and three control lines were screened for resistance to Beet curly top virus in 2013. Commercial cultivars ‘Monohikari’ (susceptible), ‘HM PM90’ (resistant) and Betaseed line Beta G6040 (resistant) were included as controls. The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID, using standard agronomic practices. The plots were two rows 10 ft long with 22-in row spacing and arranged in a randomized complete block design with four replications. The fields were sprinkler irrigated and hand weeded as necessary. Plant populations were thinned to about 47,500 plants. Plants were inoculated at the four- to six-leaf growth stage with approximately six curly top infected beet leafhoppers per plant. The plots were rated for leaf symptom development using a scale of 0-9 (0 = healthy and 9 = dead). Data were analyzed for mean comparisons. Development of curly top disease symptoms was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was severe with good symptom development in the susceptible control. Thirty-five entries tested were not significantly different from the resistant control (Beta G6040) but were better than the susceptible control (Monohikari). Of those 35 entries, 15 were germplasm being evaluated for release based on a number of factors, including resistance to curly top. Decisions to release these germplasm to commercial plant breeders will be based on their total performance, including resistance to curly top. Among the 35 best performing entries were 20 selfed single plant families. The top 3 of the resistant families (based on severity scores) will be grown from remaining seed and further developed for eventual release as enhanced germplasm to commercial breeders and other researchers.

Technical Abstract: Seventy-one sugar beet (Beta vulgaris L.) lines from the USDA-ARS Ft. Collins sugar beet program and three control lines were screened for resistance to Beet curly top virus (BCTV) in 2013. Commercial cultivars ‘Monohikari’ (susceptible), ‘HM PM90’ (resistant) and Betaseed line Beta G6040 (resistant) were included as controls. The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID, and was grown using typical agronomic practices. The plots were two rows 10 ft long with 22-in row spacing and arranged in a randomized complete block design with four replications. Plants were inoculated at the four- to six-leaf growth stage on June 27 with approximately six viruliferous beet leafhoppers per plant. The beet leafhoppers were redistributed twice a day (immediately after sunrise and just before sunset) for one week by dragging a tarp through the field to disrupt settled/feeding leafhoppers. The plots were rated for foliar symptom development on July16 using a scale of 0-9 (0 = healthy and 9 = dead), with the scale treated as a continuous variable. Data were analyzed using the general linear models procedure, and Fisher’s protected least significant difference (a = 0.05) was used for mean comparisons. Development of curly top disease symptoms was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was severe with good symptom development in the susceptible control. Beta G6040, HM P90, and Monohikari were rated at 4.2, 4.4, and 6.3, respectively. The field was confirmed to be predominantly infected with Beet curly top virus (BCTV) and Beet severe curly top virus (BSCTV), with minimal infection by Beet mild curly top virus (BMCTV), using species-specific PCR. Thirty-five entries tested were not significantly different from the resistant control (Beta G6040) based on visual symptoms but were significantly better than the susceptible control (Monohikari). Of those 35 entries, 15 were germplasm being evaluated for release based on a number of factors, including resistance to curly top. Decisions to release these germplasm to commercial plant breeders will be based on their total performance, including resistance to curly top. Among the 35 best performing entries were 20 selfed single plant families of the cross (07-FC1015-420/C833-5cms)/FC201. The top 3 of the resistant families based on severity scores will be grown from remnant seed, recombined, tested against other pathogens, and further developed for eventual release as enhanced germplasm to commercial breeders and other researchers.

Last Modified: 10/1/2014
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