The Evolutionary History of Beet necrotic yellow vein virus Deduced from Genetic Variation, Geographical Origin and Spread, and the Breaking of Host Resistance

Abstract

Beet necrotic yellow vein virus (BNYVV) is an economically important pathogen of sugar beet and has been found worldwide, probably as the result of recent worldwide spread. The BNYVV genome consists of four or five RNA components. Here, we report analysis of sequence variation in the RNA3-p25, RNA4-p31, RNA2-CP, and RNA5-p26 genes of 73 worldwide isolates. The RNA3-p25 gene encodes virulence and avirulence factors. These four sets of gene sequences each fell into two to four groups, of which the three groups of p25 formed eight subgroups with different geographical distributions. Each of these subgroup isolates (strains) could have arisen from four original BNYVV population and their mixed infections. The genetic diversity for BNYVV was relatively small. Selection pressure varied greatly depending on the BNYVV gene and geographical location. Isolates of the Italy strain, in which p25 was subject to the strongest positive selection, were able to overcome the Rz1-host resistance gene to differing degrees, whereas other geographically limited strains could not. Resistance-breaking variants were generated by p25 amino acid changes at positions 67 and 68. Our studies suggest that BNYVV originally evolved in East Asia and has recently become a pathogen of cultivated sugar beet followed by the emergence of new resistance-breaking variants.

Genetic diversity and population structure of beet necrotic yellow vein virus in China

“…J type isolates possess two deletions at amino acid positions 77 and 227-229 in p26, compared to the P type (Schirmer et al, 2005). P type BNYVV only occurs in France, the United Kingdom and Kazakhstan (Koenig et al, 1997;Koenig and Lennefors, 2000;Ward et al, 2007), and the J type mainly occurs in Japan, China and a single field in Germany (Chiba et al, 2011;Li et al, 2008;Koenig et al, 2008).…”

“…BNYVV can be classified into four genotypes (Schirmer et al, 2005;Chiba et al, 2011). A and B types contain four RNAs, and the differences at amino acid positions 62, 103 and 172 of the CP gene allowed us to distinguish between A type (T 62 S 103 L 172 ) and B type (S 62 N 103 F 172 ) isolates (Miyanishi et al, 1999).…”

Characterization of a Novel Megabirnavirus from Sclerotinia sclerotiorum Reveals Horizontal Gene Transfer from Single-Stranded RNA Virus to Double-Stranded RNA Virus

“…However, MyRV3 is still considered a mycoreovirus with a 12-segment genome (45). Field isolates of beet necrotic yellow vein virus (BNYVV), a multipartite ϩssRNA virus, usually consist of five RNA components, whereas only the two or three largest segments are responsible for systemic infection of host plants in the laboratory (46,47,48). However, researchers still describe the BNYVV genome as consisting of five segments.…”

Detection of Beet Necrotic Yellow Vein Virus by Double Stranded RNA Analysis

“…Rhizomania causes serious disease of sugar beet. It was first reported in Italy in the 1950s (Canova, 1959) but now it is present in sugar beet areas all over the world (Chiba et al, 2011). BNYVV is transmitted in soil by zoospores of plasmodiophorid, Polymyxa betae (Keskin, 1964).…”