Effects of the culture filtrate of Fusarium oxysporum f. sp. lycopersici on tomato callus growth and the selection of resistant callus cells to the filtrate.

Abstract

The effect of the culture filtrate of Fusarium oxysporum f. sp. lycopersici on the growth of tomato callus, and the induction and selection of resistant callus to the culture filtrate were examined by using callus tissues originated from germinating seeds and axillary buds of tomato. In the plants treated with crude filtrate and Millipore filter-filtered culture filtrate (MFF) of Fusarium, the degree or timing of the wilt occurrence was closely similar in both plants. Autoclaved culture filtrate (AF) also induced the wilt in tomato plants though the occurrence was delayed. Lethal effect of the culture filtrate on tomato callus cells was dose-dependent as examined by FDA-staining and the survival rates of the cells in each callus clump treated with the culture filtrate corresponded to the degree or timing of browning in callus clump. Under a positive selection-condition where wild type cells were completely killed, AF-resistant calli were successfully induced and selected after mutagenization with N-methyl-N'-nitro-N-nitrosoguanidine. However, the MFF-resistant calli were not selected.