The Symptoms and Cause of Guava Wilt in South Africa

The full-length vanilla necrosis potyvirus (VNV) coat protein (CP) gene was introduced into .Nicotiana benthamiana plants via Agrobacterium tumefaciensmediated transformation. Four constructs contained either: sense ( + ) CP sequence, antisense ( —) CP sequence, sense CP sequence with a Kozakʹs consensus ATG resulting in a change in the first amino acid, or antisense CP sequence with the Kozakʹs modification. When mechanically inoculated with a high concentration of VNV, one of the plant lines containing the full-length sense CP gene was highly resistant to virus infection. Plants from the resistant lines expressed the CP at a relatively low level compared to susceptible lines containing the same construct. Plants containing the other three constructs were either susceptible or showed delayed symptom expression