Abstract
The stimulation exerted by the endophytic bacterium Bacillus pumilus strain SE34 in plant defense reactions was investigated at the ultrastructural level using an in vitro system in which root-inducing T-DNA pea (Pisum sativum L.) roots were infected with the pea root-rotting fungus Fusarium oxysporum f. sp. pisi. In nonbacterized roots, the pathogen multiplied abundantly through much of the tissue including the vascular stele, whereas in prebacterized roots, pathogen growth was restricted to the epidermis and the outer cortex In these prebacterized roots, typical host reactions included strengthening the epidermal and cortical cell walls and deposition of newly formed barriers beyond the infection sites. Wall appositions were found to contain large amounts of callose in addition to being infiltrated with phenolic compounds. The labeling pattern obtained with the gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged, bacterized roots. Such compounds accumulated in the host cell walls and the intercellular spaces as well as at the surface or even inside of the invading hyphae of the pathogen. The wall-bound chitin component in Fusarium hyphae colonizing bacterized roots was preserved even when hyphae had undergone substantial degradation. These observations confirm that endophytic bacteria may function as potential inducers of plant disease resistance.
Full Text
The Full Text of this article is available as a PDF (3.8 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Benhamou N., Gilboa-Garber N., Trudel J., Asselin A. A new lectin-gold complex for ultrastructural localization of galacturonic acids. J Histochem Cytochem. 1988 Nov;36(11):1403–1411. doi: 10.1177/36.11.3049790. [DOI] [PubMed] [Google Scholar]
- Campbell J. R., Lawson D. D., Wyburn R. S. Coxofemoral luxation in the dog. Vet Rec. 1965 Oct 2;77(40):1173–1177. [PubMed] [Google Scholar]
- Fiddaman P. J., Rossall S. The production of antifungal volatiles by Bacillus subtilis. J Appl Bacteriol. 1993 Feb;74(2):119–126. doi: 10.1111/j.1365-2672.1993.tb03004.x. [DOI] [PubMed] [Google Scholar]
- Leifert C., Li H., Chidburee S., Hampson S., Workman S., Sigee D., Epton H. A., Harbour A. Antibiotic production and biocontrol activity by Bacillus subtilis CL27 and Bacillus pumilus CL45. J Appl Bacteriol. 1995 Feb;78(2):97–108. doi: 10.1111/j.1365-2672.1995.tb02829.x. [DOI] [PubMed] [Google Scholar]
- Lewis N. G., Yamamoto E. Lignin: occurrence, biogenesis and biodegradation. Annu Rev Plant Physiol Plant Mol Biol. 1990;41:455–496. doi: 10.1146/annurev.pp.41.060190.002323. [DOI] [PubMed] [Google Scholar]
- Patriquin D. G., Döbereiner J. Light microscopy observations of tetrazolium-reducing bacteria in the endorhizosphere of maize and other grasses in Brazil. Can J Microbiol. 1978 Jun;24(6):734–742. doi: 10.1139/m78-122. [DOI] [PubMed] [Google Scholar]
- Priest F. G. Extracellular enzyme synthesis in the genus Bacillus. Bacteriol Rev. 1977 Sep;41(3):711–753. doi: 10.1128/br.41.3.711-753.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Savary B. J., Flores H. E. Biosynthesis of defense-related proteins in transformed root cultures of Trichosanthes kirilowii Maxim. var japonicum (Kitam.). Plant Physiol. 1994 Nov;106(3):1195–1204. doi: 10.1104/pp.106.3.1195. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Uknes S., Mauch-Mani B., Moyer M., Potter S., Williams S., Dincher S., Chandler D., Slusarenko A., Ward E., Ryals J. Acquired resistance in Arabidopsis. Plant Cell. 1992 Jun;4(6):645–656. doi: 10.1105/tpc.4.6.645. [DOI] [PMC free article] [PubMed] [Google Scholar]