PLANT PHYSIOLOGY , Vol 104, Issue 1 59-66, Copyright © 1994 by American Society of Plant Biologists
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PLANT-MICROBE INTERACTIONS |
[beta]-Aminobutyric Acid Induces the Accumulation of Pathogenesis-Related Proteins in Tomato (Lycopersicon esculentum L.) Plants and Resistance to Late Blight Infection Caused by Phytophthora infestans
Y. Cohen, T. Niderman, E. Mosinger and R. Fluhr
Department of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel (Y.C.);
Tomato (Lycopersicon esculentum L.) plants were sprayed with aqueous
solutions of isomers of aminobutyric acid and were either analyzed for the
accumulation of pathogenesis-related (PR) proteins or challenged with the
late blight fungal agent Phytophthora infestans. The [beta] isomer of
aminobutyric acid induced the accumulation of high levels of three
proteins: P14a, [beta]-1,3 glucanase, and chitinase. These proteins either
did not accumulate or accumulated to a much lower level in [alpha]- or
[gamma]-aminobutyric acid-treated plants. Plants pretreated with [alpha]-,
[beta]-, and [gamma]-aminobutyric acid were protected up to 11 d to an
extent of 35, 92, and 6%, respectively, against a challenge infection with
P. infestans. Protection by [beta]-aminobutyric acid was afforded against
the blight even when the chemical was applied 1 d postinoculation.
Examination of ethylene evolution showed that [alpha]-aminobutyric acid
induced the production of 3-fold higher levels of ethylene compared with
[beta]-aminobutyric acid, whereas [gamma]-aminobutyric acid induced no
ethylene production. In addition, silver thiosulfate, a potent inhibitor of
ethylene action, did not abolish the resistance induced by
[beta]-aminobutyric acid. The results are consistent with the possibility
that [beta]-aminobutyric acid protects tomato foliage against the late
blight disease by a mechanism that is not mediated by ethylene and that PR
proteins can be involved in induced resistance.
