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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #167500
Title: OCCURRENCE OF RESISTANCE BREAKING BEET NECROTIC YELLOW VEIN VIRUS OF SUGAR BEET.

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

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2005
Publication Date: 5/20/2005
Citation: Liu, H., Sears, J.L., Lewellen, R.T. 2005. Occurrence of resistance breaking beet necrotic yellow vein virus of sugar beet. Plant Disease. 89:464-468.

Interpretive Summary: Rhizomania is a serious disease of sugar beet. This disease is caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae. The major problem to control rhizomania disease is that the resting spore of the viruliferous fungal vector is able to survive in the soil for at least 15 years. Hence, use resistant cultivars have been the only economical way to control this devastating disease. Partially resistant sugar beet cultivars based upon single dominant genes have been developed and are widely used by the sugar beet industry. In the summer of 2002, three sugar beet fields planted with a BNYVV-resistant cultivar in the Imperial Valley of California were observed to exhibit 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 from pertinent fields all resistant varieties tested susceptible according to elevated ELISA values. Inoculum potential did not change these relationships. Based on host reaction, eight distinct BNYVV isolates have been identified 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 for all of the isolates, the banding patterns were identical to A-type and different from P-type. Our results indicate that the resistance-breaking BNYVV isolates from Imperial Valley likely evolved from existing A-type.

Technical Abstract: Rhizomania is an important virus disease of sugar beet. This disease is caused by Beet necrotic yellow vein virus (BNYVV). Partially resistant sugar beet cultivars based upon single dominant genes have been developed against this devastating disease. Since 2002 several sugar beet fields with BNYVV-resistant cultivars in the Imperial Valley of California were observed with severe 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 from pertinent fields all resistant varieties tested susceptible according to elevated ELISA values. Inoculum potential did not change these relationships. Based on host reaction, eight distinct BNYVV isolates have been identified 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 for all of the isolates, the banding patterns were identical to A-type and different from P-type. Our results indicate that the resistance-breaking BNYVV isolates from Imperial Valley likely evolved from existing A-type.