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United States Department of Agriculture

Agricultural Research Service

Title: Inheritance of Powdery Mildew Resistance in Sugar Beet Derived from Beta Vulgaris Ssp. Maritima

Authors
item Lewellen, Robert
item Schrandt, Julia

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2001
Publication Date: June 1, 2001

Interpretive Summary: Powdery mildew of sugar beet (Beta vulgaris L.) caused by Erysiphe polygoni DC was introduced into N. America in 1974. Since then, chemical control has been needed. Traditional North American sugar beet cultivars and germplasm largely proved to be highly susceptible. Yield losses greater than 30% were measured. Moderate resistance of a slow-mildewing type is known and has been used commercially. High resistance was identified, recently, in B. vulgaris ssp. maritima accessions WB97 and WB242 and has been backcrossed into sugar beet breeding lines. These enhanced lines were used as sources of powdery mildew resistance to determine the inheritance of resistance. Analyses of segregating testcross and S1 families showed that resistance from both sources is inherited as a single dominant major gene. The gene symbol Pm is proposed for the resistant allele. This high resistance to powdery mildew may help to alleviate the damage caused by this disease and reduce the dependence upon chemical control.

Technical Abstract: Powdery mildew of sugar beet (Beta vulgaris L.) caused by Erysiphe polygoni DC was introduced into N. America in 1974. Since then, chemical control has been needed. Moderate resistance of a slow-mildewing type is known and has been used commercially. High resistance was identified, recently, in B. vulgaris ssp. maritima accessions WB97 and WB242 and has been backcrossed into sugar beet breeding lines. These enhanced lines were used as sources of powdery mildew resistance to determine the inheritance of resistance. Analyses of segregating testcross and S1 families showed that resistance from both sources is inherited as a single dominant major gene. The gene symbol Pm is proposed for the resistant allele. The allelism of the resistance from the two wild beet sources was not determined. Pm conditions a high level of resistance, but disease development on matured leaves in late season was observed. This late mildew development in resistant genotypes and the slow-mildewing trait in susceptible recurrent genotypes tended to obfuscate discrete disease ratings.

Last Modified: 10/24/2014
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