Cell wall oligosaccharides from Fusarium oxysporum elicit defense responses in pearl millet against downy mildew pathogen.

Roopa, K. S. and Geetha, N. P. and Prakash, H. S. and Shetty, H. Shekar (2006) Cell wall oligosaccharides from Fusarium oxysporum elicit defense responses in pearl millet against downy mildew pathogen. Journal of Mycology and Plant Pathology, 36 (3, Cop). pp. 385-391. ISSN 0971-9393

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Oligosaccharides derived from fungal and plant cell wall polysaccharides are one class of well-characterized elicitors that induce defense responses in plants. A few attempts have been made to purify the fractions of Fusarium oxysporum oligosaccharide components as an elicitor. However, structural elucidation of oligosaccharides and its effect on plant tissues for eliciting defense responses like hypersensitive reaction (HR) in biotrophic host-pathogen interactions has not been reported. Hence, in the present study, F. oxysporum was isolated from muskmelon seed of cv. Cms1606 and the crude oligosaccharide was extd. from mycelial mats. The crude ext. was subjected to purifn. by size exclusion chromatog. fractionation and sepd. into five fractions. Fractions I and II contained both carbohydrates and proteins, while fraction III, IV and V contained only carbohydrates. Seeds of pearl millet cv. 7042S were treated with individual purified fractions at 10 nM concns. Interestingly, all the fractions expressed HR in seedlings inoculated with Sclerospora graminicola but differed in the degree of elicitation. Fraction IV exhibited max (96 %) seedlings showing HR at 24 h after inoculation with pathogen. At the place of attempted penetration of pathogen, the host tissues showed a high amt. of lignification due to elicitation. A greater difference in the lignification was obsd. in seeds primed with purified fraction IV, which was comparable to the unprimed but pathogen inoculated resistant control. Therefore, we focused our interest on fraction IV to structurally identify and characterize the oligosaccharide. The 1H NMR spectrum of the oligosaccharide fraction IV displayed three signals in the anomeric regions at 4.7, 3.58 and 1.97 ppm. The chem. resonance at 1.97 ppm and 3.58 ppm was identified to be of N-acetyl-D-glucosamine oligomer. Up to now, no characterized oligosaccharide elicitor is reported to cause HR. This is the first report to demonstrate that oligosaccharide of fungal origin induces HR in pearl millet against downy mildew disease. Significance of this result is discussed for developing a seed priming oligomer to control downy mildew disease. [on SciFinder(R)]

Item Type: Article
Additional Information: Unmapped bibliographic data: PY - 2006/// [EPrints field already has value set] JA - J. Mycol. Plant Pathol. [Field not mapped to EPrints]
Uncontrolled Keywords: Fusarium Pennisetum downy mildew disease resistance oligosaccharide
Subjects: Agriculture Biological Sciences > Biotechnology
University of Mysore > PG Campuses > Manasagangotri, Mysore > Agriculture Biological Sciences > Biotechnology
Divisions: PG Campuses > Manasagangotri, Mysore > Biotechnology
Depositing User: Dhruvakumar
Date Deposited: 04 Jun 2013 05:50
Last Modified: 04 Jun 2013 05:50
URI: http://eprints.uni-mysore.ac.in/id/eprint/11837

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