Abstract
Infection of plants by necrotizing pathogens can induce broad-spectrum resistance to subsequent pathogen infection. This systemic acquired resistance (SAR) is thought to be triggered by a vascular-mobile signal that moves throughout the plant from the infected leaves. A considerable amount of evidence suggests that salicylic acid (SA) is involved in the induction of SAR. Because SA is found in phloem exudate of infected cucumber and tobacco plants, it has been proposed as a candidate for the translocated signal. To determine if SA is the mobile signal, grafting experiments were performed using transgenic plants that express a bacterial SA-degrading enzyme. We show that transgenic tobacco root-stocks, although unable to accumulate SA, were fully capable of delivering a signal that renders nontransgenic scions resistant to further pathogen infection. This result indicated that the translocating, SAR-inducing signal is not SA. Reciprocal grafts demonstrated that the signal requires the presence of SA in tissues distant from the infection site to induce systemic resistance.
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- Alexander D., Goodman R. M., Gut-Rella M., Glascock C., Weymann K., Friedrich L., Maddox D., Ahl-Goy P., Luntz T., Ward E. Increased tolerance to two oomycete pathogens in transgenic tobacco expressing pathogenesis-related protein 1a. Proc Natl Acad Sci U S A. 1993 Aug 1;90(15):7327–7331. doi: 10.1073/pnas.90.15.7327. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bowles D. J. Defense-related proteins in higher plants. Annu Rev Biochem. 1990;59:873–907. doi: 10.1146/annurev.bi.59.070190.004301. [DOI] [PubMed] [Google Scholar]
- Chen Z., Silva H., Klessig D. F. Active oxygen species in the induction of plant systemic acquired resistance by salicylic acid. Science. 1993 Dec 17;262(5141):1883–1886. doi: 10.1126/science.8266079. [DOI] [PubMed] [Google Scholar]
- Enyedi A. J., Yalpani N., Silverman P., Raskin I. Localization, conjugation, and function of salicylic acid in tobacco during the hypersensitive reaction to tobacco mosaic virus. Proc Natl Acad Sci U S A. 1992 Mar 15;89(6):2480–2484. doi: 10.1073/pnas.89.6.2480. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gaffney T., Friedrich L., Vernooij B., Negrotto D., Nye G., Uknes S., Ward E., Kessmann H., Ryals J. Requirement of salicylic Acid for the induction of systemic acquired resistance. Science. 1993 Aug 6;261(5122):754–756. doi: 10.1126/science.261.5122.754. [DOI] [PubMed] [Google Scholar]
- Löffelhardt W., Kindl H. The conversion of L-phenylalanine into benzoic acid on the thylakoid membrane of higher plants. Hoppe Seylers Z Physiol Chem. 1975 May;356(5):487–493. doi: 10.1515/bchm2.1975.356.1.487. [DOI] [PubMed] [Google Scholar]
- Malamy J., Carr J. P., Klessig D. F., Raskin I. Salicylic Acid: a likely endogenous signal in the resistance response of tobacco to viral infection. Science. 1990 Nov 16;250(4983):1002–1004. doi: 10.1126/science.250.4983.1002. [DOI] [PubMed] [Google Scholar]
- Mauch F., Mauch-Mani B., Boller T. Antifungal Hydrolases in Pea Tissue : II. Inhibition of Fungal Growth by Combinations of Chitinase and beta-1,3-Glucanase. Plant Physiol. 1988 Nov;88(3):936–942. doi: 10.1104/pp.88.3.936. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Métraux J. P., Signer H., Ryals J., Ward E., Wyss-Benz M., Gaudin J., Raschdorf K., Schmid E., Blum W., Inverardi B. Increase in salicylic Acid at the onset of systemic acquired resistance in cucumber. Science. 1990 Nov 16;250(4983):1004–1006. doi: 10.1126/science.250.4983.1004. [DOI] [PubMed] [Google Scholar]
- ROSS A. F. Systemic acquired resistance induced by localized virus infections in plants. Virology. 1961 Jul;14:340–358. doi: 10.1016/0042-6822(61)90319-1. [DOI] [PubMed] [Google Scholar]
- WEINTRAUB M., KEMP W. G. Protection with carnation mosaic virus in Dianthus barbatus. Virology. 1961 Feb;13:256–257. doi: 10.1016/0042-6822(61)90060-5. [DOI] [PubMed] [Google Scholar]
- Ward E. R., Uknes S. J., Williams S. C., Dincher S. S., Wiederhold D. L., Alexander D. C., Ahl-Goy P., Metraux J. P., Ryals J. A. Coordinate Gene Activity in Response to Agents That Induce Systemic Acquired Resistance. Plant Cell. 1991 Oct;3(10):1085–1094. doi: 10.1105/tpc.3.10.1085. [DOI] [PMC free article] [PubMed] [Google Scholar]