Response of cactus and nicotiana glutinosa leaves to infection by soft rot bacteria

ABSTRACT

All tested isolates of E. carotovora subsp. carotovora were able to induce hyperseitsitive reactioin [HR] in leaves of cactus and Nicotiana glutinosa plants. Unwashed cells of the less virulent isolate Et of the subsp. carotovora induced HR in cactus leaves after a longer period. Moreover, unwashed cells of E.carotovora subsp. atroseptica isolate Epo2 induced the weakest reaction. When cactus leaves were injected with washed cells of the same isolates the latent period decreased to 3 days and the browning of lesion colour occurred faster, at the 10th day, the more virulent isolates induced HR within a shorter period, whereas with the less virulent isolates, the time required for such reaction was not affected or even increased. When N.glutinosa leaves were injected with unwashed cells of highly [EP2] and moderately [Et] virulent isolates of subsp. carotovora the HR become visible after a short period. This time period increased when the washed cells of those two isolates [EP2 and Et] were used for injection. In contrast E.c.subsp. atroseptica did not induce HR in N.glutinosa leaves. Cell-free culture filtrates prepared of any tested bacterial isolates of both subsp. caused in leaves of cactus and N.glutinosa a HR moderate in intensity and after a shortest time period