SYSTEMIC TRANSLOCATION OF C-14 DL-3-AMINOBUTYRIC ACID IN TOMATO PLANTS IN RELATION TO INDUCED RESISTANCE AGAINST PHYTOPHTHORA-INFESTANS

This paper provides evidence that the systemic resistance induced by D L-3-amino-n-butanoic acid, beta-aminobutyric acid (BABA), against late blight in tomato is associated with the systemic acropetal translocat ion of BABA in the plant. Thus, when C-14-BABA was applied to the bott om leaves, the upper, but not the adjacent leaves, accumulated the com pound and the upper leaves only were protected against disease. Simila rly, when BABA was applied to the root system it was preferentially tr anslocated to the uppermost leaves and these leaves showed the greates t protection. These data support the hypothesis that resistance induce d by BABA is dependent on the actual presence of the compound in the l eaf. Almost all C-14-BABA supplied to the tomato plants was recovered unchanged with only a small proportion of the C-14-label being retaine d by cell wall fractions, probably in the form of covalently-bound pro teins. We suggest that apart from enhancing pathogenesis-related prote in accumulation in tomato, BABA alters cell wall structure or metaboli sm so making the tissues more resistant to fungal enzyme attack.