The treatment of muskmelon cultivar "Wangwenxiang", which is sensitive to w
atermelon mosaic virus-2 (WMV-2), with oxalate increases systemic resistanc
e of the cultivar to WMV-2 significantly, The challenge inoculation experim
ents indicate that the symptom of oxalate-treated plant is much slighter th
an that of control plants and the virus content is only 4% of that of contr
ol plants. The peroxidase activity of oxalate-treated plant is six times of
that of control plants; three new isoperoxidases are induced and lignin co
ntent increases by 82.9%. These results indicate that oxalate induces syste
mic resistance of muskmelon to WMV-2 while it induces increase of peroxidas
e activity.