Mycorrhiza-Related Chitinase and Chitosanase Activity Isoforms in Medicago truncatula Gaertn.
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Date
2002
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Abstract
After inoculation with the arbuscular mycorrhizal fungus Glomus mosseae, additional chitinase and chitosanase isoforms were detected in Medicago truncatula roots. Chitinase isoforms had isoelectric points between 5.3 and 5.8 and apparent molecular weights of 30 to 40 kDa. Western blotting demonstrated the cross-reactivity of the 30 kDa isoforms with a winged bean class I chitinase and a class III chitinase from chickpea, while the 40 kDa isoform only cross-reacted with the class III chitinase from chickpea. Inoculation with other soil microorganisms showed that these isoforms were strictly induced during the mycorrhizal process. Chitosanase isoforms had apparent molecular weights of 18 to 21 kDa. The three basic isoforms could be detected in nodules isolated from Sinorhizobium me/i'Zofi-inoculated plants, whereas the two acidic isoforms were strictly induced during mycorrhization. Elicitation with various chitooligosaccharides neither induced any of the mycorrhiza-related chitinase and chitosanase isoforms, nor had an effect on mycorrhizal infection, after subsequent transplantation of elicited plants into pots containing G. mosseae inoculum. A hypothetical role of chitinases and chitosanases in the formation and/or degradation of arbuscules, is discussed.
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Keywords
Arbuscular mycorrhizal symbiosis, Medicago truncatula, Glomus mosseae, elicitor, chitinase, chitosanase
Citation
Symbiosis, 32 (2002) 173-194