Abstract
Tomato plants inoculated with an avirulent strain of Pseudomonas solanacearum (strain Str-10 op type) produced a growth inhibitory substance at a higher level than those of uninoculated control in root system but not in stem. The substance was identified to be tomatine by Mass Spectrometry, TLC, UV spectrometry and chemical component analysis. The tomatine contents five days after inoculation were 113 and 152μg/g fresh root when Str-10 op type was inoculated at the inoculum concentrations of 108 and 109cfu/ml, respectively. Tomatine content in the uninoculated control plants was 65.9μg/g. Tomatine content nine days after inoculation reached 450μg/g. In an in vitro experiment, 100μg/disk of authentic tomatine and approximately 150μg/disk of extracted tomatine were sufficient for growth inhibition of P. solanacearum. Both extracted and authentic tomatine exhibited bacteriostatic activity against P. solanacearum. Treatment with heat-killed cells or culture filtrate of Str-10 op type failed to increase tomatine content in the root tissue.
