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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sugarbeet Research » Research » Publications at this Location » Publication #430957
Research Project: Improving Sugarbeet Productivity and Sustainability through Genetic, Genomic, Physiological, and Phytopathological Approaches

Location: Sugarbeet Research

Title: High natural variation of BvCR4 homologs in sea beet contrasts with narrow genetic base of sugar beet: Implications for Cercospora beticola resistance

Author
item MARTINEZ, ANA LAURA - North Dakota State University
item WYATT, SAMUEL - Mayo Clinic
item Neubauer, Jonathan
item Reeves, Patrick
item Richards, Christopher
item Chu, Chenggen
item BRANCH, ERIC - North Dakota State University
item Bolton, Melvin
item Wyatt, Nathan

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cercospora leaf spot , caused by Cercospora beticola, is a destructive sugar beet disease that is managed through the application of fungicides and sugar beet varieties with resistance to CLS. Recently, new sugar beet varieties carrying the CLS resistance gene BvCR4 have been deployed widely across sugar beet producing regions and in turn, the C. beticola population has adapted to BvCR4 mediated resistance resulting in local outbreaks of CLS. In this study, we identified BvCR4-like resistance genes in publicly available germplasm from sugar beet and the sugar beet wild relative sea beet. We further explored the genetic and structural variation of these BvCR4-like genes and showed that genes derived from sea beet were more diverse than those derived from sugar beet. This work highlights the narrow genetic diversity of cultivated sugar beet and the relatively higher genetic diversity of the wild sea beet population in publicly available germplasm. BvCR4-like resistance genes identified can now be evaluated for their potential to condition resistance to CLS and will be valuable resources for incorporating additional CLS resistance into elite sugar beet hybrids.

Technical Abstract: Cercospora leaf spot (CLS) is a destructive disease of sugar beet (Beta vulgaris ssp. vulgaris L.) for which resistance conferred by the BvCR4 gene has been introgressed from sea beet (B. vulgaris ssp. maritima). BvCR4-mediated resistance has been widely deployed to manage CLS globally; however, continuous implementation exerts strong selection pressure, increasing the risk of resistance breaking disease outbreaks. This study aimed to identify BvCR4 variants in public beet germplasm to assess their genetic and structural diversity. PCR screening of 589 public B. vulgaris spp. germplasm detected BvCR4 homologs in 32 accessions with diverse responses to CLS including historically relevant sugar beet lines represented in breeding programs and Mediterranean sea beet populations of diverse genetic backgrounds. Analysis of the genomic sequences revealed higher diversity in sea beet compared to sugar beet. Additionally, population genetic analysis indicated that BvCR4 homologs in sugar beet likely originated from sea beet populations in Italy and Greece. We defined historical cultivated materials carrying full proteins encoded by BvCR4 alleles and delineated geographic regions where sea beet populations harbor BvCR4 homologs that may be useful in breeding programs. Structural variation was largely circumscribed within leucine-rich repeat domains, although CLS resistance phenotyping was not associated with specific polymorphisms, suggesting BvCR4-mediated resistance may rely on interactions with other co-receptors. This study provides resources for sugar beet improvement by enabling the identification of BvCR4 homologs in diverse germplasm and disclosing materials with potentially novel resistance.