Mode of action of the resistance-inducing 3-aminobutyric acid in tomato roots against Fusarium wilt / Wirkungsweise des Resistenzinduktors 3-Aminobuttersäure in Tomatenwurzeln gegenüber der Fusarium-Welke

• Published in: Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz (1970) 2004-05, Vol.111 (3), p.273-291
• Main Authors: Chamsai, Jutta, Siegrist, J., Buchenauer, H.
• Format: Article
• Language: English
• Subjects: Cell walls; Disease resistance; Fusarium; Induced resistance; Inoculation; Mode of action; Pathogens; Plant diseases; Plant roots; Plants
• ISSN: 0340-8159; 2364-9968

In the present work, the modes of action of the resistance inducer DL-3-aminobutyric acid (DL-3-ABA) were studied in the host-pathogen-interaction tomato/Fusarium oxysporum f. sp. lycopersici (Fol) by using physiological and biochemical methods. Under glasshouse conditions, tomato plants pretreated by soil drench with DL-3-ABA and the R-enantiomer of 3-ABA were strongly protected against infection by Fol. On the other hand, pre-treatments with the two isomers DL-2-aminobutyric acid and 4-aminobutyric acid as well as with the S-enantiomer of 3-ABA induced no resistance against Fusarium wilt. Light microscopical studies 4 weeks after inoculation with Fol revealed that in control plants the pathogen spread via the xylem into the shoot of tomato plants, while in DL-3-ABA-pretreated plants the pathogen was restricted to the roots and the hypocotyl. Infected xylem vessels collapsed and were replaced by new xylem tissue. Further experiments focused on the resistance-inducing effects in roots during early phases between treatment with the inducer and infection. Two to 3 days after application of DL-3-ABA or the R-enantiomer, necrotic lesions developed on tomato roots. This local cell death correlated with the induction of resistance by DL-3-ABA. Local cell death was often accompanied by an increase of salicylic acid (SA). Following application of 3-ABA and its R-enantiomer, an increased level of free and glucosylated SA in tomato roots was detected, while SA levels only slightly increased after treatment with the S-enantiomer. Furthermore, in roots of tomato plants treated with DL-3-ABA, protein content was higher than in roots of control plants. The PR-proteins chitinase, β-1,3-glucanase and P14 (PR-1) were increased. Also, enhanced activities of the enzymes peroxidase and polyphenoloxidase were detected. An increase of monomeric and polymeric bound phenolics hints towards an enforcement of cell walls, which possibly impeded spreading of the pathogen. The stereopecificity of DL-3-ABA revealed that only the R-enantiomer was active. This might suggest a very specific perception of the inducer in plants, leading via development of necrosis and synthesis of SA to activation of defense reactions. Im Rahmen dieser Arbeit wurden mit Hilfe physiologischer und biochemischer Methoden Wirkungsmechanismen des Resistenzinduktors DL-3-Aminobuttersäure (DL-3-ABS) an der Wirt-Pathogen-Interaktion Tomate/Fusarium oxysporum f. sp. lycopersici (Fol) untersucht. Die Resistenzprüfung