Find in Library

<i>Brassica juncea</i> belongs to the <i>Brassicaceae</i> family and is used as both an oilseed and vegetable crop. As only a few studies have reported on the cucumber mosaic virus (CMV) in <i>B. juncea</i>, we conducted this study to provide a basic understanding of the <i>B. juncea</i> and CMV interactions. <i>B. juncea</i>-infecting CMV (CMV-Co6) and non-infecting CMV (CMV-Rs1) were used. To identify the determinants of systemic infection in <i>B. juncea</i>, we first constructed infectious clones of CMV-Co6 and CMV-Rs1 and used them as pseudo-recombinants. RNA2 of CMV was identified as an important determinant in <i>B. juncea</i> because <i>B. juncea</i> were systemically infected with RNA2-containing pseudo-recombinants; CMV-Co6, R/6/R, and R/6/6 were systemically infected <i>B. juncea</i>. Subsequently, the amino acids of the 2a and 2b proteins were compared, and a chimeric clone was constructed. The chimeric virus R/6Rns/R6cp, containing the C-terminal region of the 2a protein of CMV-Rs1, still infects <i>B. juncea</i>. It is the 2a protein that determines the systemic CMV infection in <i>B. juncea</i>, suggesting that conserved 160G and 214A may play a role in systemic CMV infection in <i>B. juncea</i>.