|Liu, Hsing Yeh|
Submitted to: Phytopathology
Publication Type: Proceedings
Publication Acceptance Date: May 20, 2004
Publication Date: June 20, 2004
Citation: Liu, H., Sears, J.L., Lewellen, R.T. 2004. Emergence of resistance-breaking isolates of beet necrotic yellow vein virus in the Imperial Valley, California. Phytopathology. 94:S62 Technical Abstract: Beet necrotic yellow vein virus (BNYVV) is the causal agent of rhizomania disease of sugar beet. The virus is transmitted by the soil-borne fungus Polymyxa betae. The disease can only be controlled by the use of resistant cultivars. During 2002 and 2003 in the Imperial Valley of California partially resistant sugar beet cultivars with Rz1 allele developed against this devastating disease have been compromised. Distinct BNYVV isolates have been isolated from infected sugar beet roots (IV-BNYVV) by single local lesion isolation. IV-BNYVV isolates do not contain RNA-5 as determined by RT-PCR. From the banding patterns of single-strand conformation polymorphism analyses we concluded that the resistance-breaking BNYVV isolates from Imperial Valley likely had evolved from the original existing A-type. The pathogenicity of IV-BNYVV isolates has been studied. PCR products from coat protein (RNA-2) and 25-kDa protein (encoded by BNYVV-RNA-3, involved in symptom expression) of IV-BNYVV isolates have been sequenced. Sequence alignments revealed only minor amino acid changes compared to the existing California BNYVV isolates.