Resistance Against Pepper Severe Mosaic Potyvirus in Transgenic Tobacco Plants

The coat protein gene of the pepper severe mosaic potyvirus was introduced into tobacco plants. Several transgenic lines were assayed for virus resistance under greenhouse conditions. Line 232, showing higher levels of resistance than other transgenic plants, was studied in further detail. Upon challenge with PepSMV, R, descendants from this line were monitored for virus accumulation for a period of 45 days. Virus titre was lower in plants of the line 232 than in control plants throughout the expedment. At 14 days post-inoculation the transgenic plant line reached the maximum virus accumulation measured by ELISA. Those plants also showed a 1 week delay of virus accumulation by comparison with control plants. After reaching the peak at 14 days post-inoculation the virus titre in line 232 decreased with respect to control plants, until the end of the expedment. These results are compatible with the presence of an RNA-mediated resistance mechanism,