Mechanisms of Resistance: Expression of Coat Protein

The expression of viral coat protein (CP) genes in transgenic plants can lead to different phenotypes of resistance (1 ). Occasionally, transgenic plants escape infection completely and do not accumulate virus or develop symptoms. In other cases, local and systemic virus accumulation and development of systemic infection proceed at a rate slower than in nontransgenic plants. In transgenic plant lines, the proportion of plants that develop symptoms after inoculation is frequently lower than in control lines. It has also been shown that transgenic plants can become locally infected and accumulate virus in the inoculated leaf, but do not support systemic infection. The different phenotypes of resistance suggest that there is not one common mechanism by which virus infection is affected in transgenic plants, but different steps of virus infection are inhibited in different host-virus combinations.