Fig. 1

Reaction of S.chacoense plants on PVY infection following mechanical inoculation. Extreme resistance – no systemic infection (A) with no lesions (not shown) or tiny necrosis on the inoculated leaf (B). Hypersensitive reaction – stem necrosis (C) with no systemic infection (D). Susceptibility – excessive stem necrosis (E) and systemic infection on leaves (F).