MDA content and enzymatic changes during resistance of cowpea to Fusarium oxysporum f.sp. tracheiphilum.

We evaluated a resistant cultivar(R,Fengchang No.2) and a susceptible cultivar(S,Zhijiang28-2) of cowpea(Vigna sesquipedalis) for changes in the activities of defence enzymes after inoculation of 2,4,6,8,10 d with Fusarium oxysporum f.sp.tracheiphilum.Preoxidase(POD),polyphenol oxidase(PPO),phenylalanine amino-lyase(PAL),catalase(CAT),chitinase and β-1,3-glucanase and the content of malonaldehyde(MDA) in leaves were analyzed.It was found that(1)The activities of 6 enzymes and MDA content showed no significant changes in uninoculated leaves both in resistant and susceptible cultivar.(2) After fungal inoculation,the activities of all enzymes were promoted,there had higher activities in PPO,CAT and MDA in the resistant cultivar comparing with the susceptible.(3)The activities of PPO,POD,CAT and chitinase changed earlier in R than in S after fungal inoculation,indicating the relationship to triggering resistant response to infection.