Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: P-Pathotype of Rhizomania in Sugar Beet Has Not Been Identified in the Imperial Valley.

Authors
item Liu, Hsing Yeh
item Sears, John
item Lewellen, Robert

Submitted to: The California Sugar Beet
Publication Type: Popular Publication
Publication Acceptance Date: February 20, 2004
Publication Date: March 20, 2004
Citation: Liu, H., Sears, J.L., Lewellen, R.T. 2004. P-pathotype of rhizomania in sugar beet has not been identified in the Imperial Valley. The California Sugar Beet, p. 12-13, 25.

Interpretive Summary: Rhizomania is one of the most economically important diseases of sugar beet. This disease is caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae. Partially resistant sugar beet cultivars based upon single dominant genes have been developed against this devastating disease. During 2002 and 2003 in the Imperial Valley of California sugar beet fields with a BNYVV-resistant cultivar were observed with sever rhizomania symptoms, suggesting that resistance had been compromised. Standard soil baiting with sugar beet plants followed by ELISA tests were used to diagnose virus occurrence and reaction. Resistant varieties grown in regular BNYVV-infested soil remained resistant. In contrast, when grown in Imperial Valley BNYVV-infested soil all resistant varieties tested susceptible according to elevated ELISA values. Eight different BNYVV isolates have been isolated from Imperial Valley soil (IV-BNYVV) by single local lesion isolation. IV-BNYVV isolates did not contain RNA-5 as determined by RT-PCR. In single-strand conformation polymorphism analyses all the isolates the banding patterns were identical to A-type and different from P-type. Our results indicate the resistance-breaking BNYVV isolates derived from existing A-type.

Technical Abstract: Rhizomania is one of the most economically important diseases of sugar beet. This disease is caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae. Partially resistant sugar beet cultivars based upon single dominant genes have been developed against this devastating disease. During 2002 and 2003 in the Imperial Valley of California sugar beet fields with a BNYVV-resistant cultivar were observed with sever rhizomania symptoms, suggesting that resistance had been compromised. Standard soil baiting with sugar beet plants followed by ELISA tests were used to diagnose virus occurrence and reaction. Resistant varieties grown in regular BNYVV-infested soil remained resistant. In contrast, when grown in Imperial Valley BNYVV-infested soil all resistant varieties tested susceptible according to elevated ELISA values. Eight different BNYVV isolates have been isolated from Imperial Valley soil (IV-BNYVV) by single local lesion isolation. IV-BNYVV isolates did not contain RNA-5 as determined by RT-PCR. In single-strand conformation polymorphism analyses all the isolates the banding patterns were identical to A-type and different from P-type. Our results indicate the resistance-breaking BNYVV isolates derived from existing A-type.

Last Modified: 12/22/2014
Footer Content Back to Top of Page