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- Title
In vitro suppression of fungal root pathogens of cereals by Brassica tissues.
- Authors
Kirkegaard, J. A.; Wong, P. T. W.; Desmarchelier, J. M.
- Abstract
The superior growth of wheat following Brassica crops compared to that following non-Brassica crops may be due to thesuppressionof soilborne fungal pathogens by volatile isothiocyanates (ITCs) released in the soil during hydrolysis of glucosinolates contained in Brassica tissues. We investigated the effects of volatile compounds released from the root, shoot and seed meal tissues of canola (Brassica napus) and Indian mustard (Brassica juncea) on the mycelial growth of five soilborne pathogens of cereals- Gaeumannomyces graminis var. tritici, Rhizoctonia solani, Fiisarium graminearum, Pythiwn irregulare and Bipolaris sorokiniana. Three isolates of each species, originally collected from the roots of wheat (Triticum aestivwn) and barley grass [Hordeum leporinum ) in southern Australia, were exposed to volatiles released in vitro when sterile water was added to freeze-dried Brassica tissues. The root and shoot tissues of both Brassica species were more suppressive at flowering than maturity and mustard tissues were generally more suppressive than canola. The degree of fungal suppression by the various Brassica tissues was related to the concentration and type of isothiocyanates released, which varied with Brassica species, tissue age and tissue type. There were significant differences in the sensitivity of the fungal species and among isolates of each species. Gaeumannomyces and Rluzoctonia were generally the most sensitive to the volatiles released, Pythiiim and Bipolaris the least. The results indicate that the effectiveness of fungal suppression by Brassic crops will depend upon the species, age and type of Brassica tissue, which influence the type and concentration of isothiocyanates evolved, and the sensitivity of the pathogen.
- Subjects
ORGANS (Anatomy); PRESERVATION of organs, tissues, etc.; BRASSICA; TISSUES; PATHOGENIC microorganisms; GLUCOSINOLATES
- Publication
Plant Pathology, 1996, Vol 45, Issue 3, p593
- ISSN
0032-0862
- Publication type
Article
- DOI
10.1046/j.1365-3059.1996.d01-143.x