The effect of PRSV on defense enzymes activity in leaf of Papaya

The changes of POD,PPO and SOD activities and POD isozyme in leaves were determined before and after infected with PRSV-Ys in a natural resistant mutant of papaya.The results showed that after infected the activities of POD and PPO in the natural resistant mutant were higher than those in susceptible cultivar Suizhonghong,and the POD and PPO increased at early stage and then decreased,and the changes in POD and PPO activities in the natural resistant mutant increased more than that of Suizhonghng.The SOD activities in Suizhonghng increased more than that of the natural resistant mutant.A POD isozyme band(Rf 0.745)appeared in the natural resistant mutant,which did not occurred in resistant variety.The changes in defense enzyme activity and POD isozyme showed much close relation to the resistance to PRSV in papaya.