Genetic Resistance to Turnip mosaic virus (TuMV) in Brassicas

Turnip mosaic virus (TuMV) is a member of the Potyvirus genus, infects a wide range of cultivated plant species and causes significant economic losses in Brassica crops (Shattuck, 1992). It is a positive strand RNA virus (genome comprises 9830-9835 nucleotides) and is the subject of advanced molecular characterisation in terms of its interaction with brassicas (Walsh & Jenner, 2002). Plant genes for resistance to TuMV have been mapped in lettuce (Tu, Robbins et al., 1994), B. napus(TuRB01, Walsh et al., 1999; TuRB03, Hughes et al., 2003; TuRB04 and TuRB05, Walsh & Lydiate, unpublished) and B. rapa (TuRB01b, Rusholme et al., unpublished). All these brassica genes are dominant R genes that control resistance to narrow spectra of TuMV isolates; the viral avirulence determinants for these genes have been identified (Jenner et al., 2000; Walsh et al., 2002; Jenner et al., 2002; Jenner et al., 2003)