Plant defensins and virally encoded fungal toxin KP4 inhibit plant root growth

Allen, A. and Snyder, A.K. and Preuss, M. and et al, . (2008) Plant defensins and virally encoded fungal toxin KP4 inhibit plant root growth. Planta, 227 (2). pp. 331-339.

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Plant defensins are small, highly stable, cysteine-rich antimicrobial proteins that are thought to constitute an important component of plant defense against fungal pathogens. There are a number of such defensins expressed in various plant tissues with differing antifungal activity and spectrum. Relatively little is known about the modes of action and biological roles of these proteins. Our previous work on a virally encoded fungal toxin, KP4, from Ustilago maydis and subsequently with the plant defensin, MsDef1, from Medicago sativa demonstrated that some of these proteins specifically blocked calcium channels in both fungi and animals. The results presented here demonstrate that KP4 and three plant defensins, MsDef1, MtDef2, and RsAFP2, all inhibit root growth in germinating Arabidopsis seeds at low micromolar concentrations. We have previously demonstrated that a fusion protein composed of Rab GTPase (RabA4b) and enhanced yellow fluorescent protein (EYFP) is dependent upon calcium gradients for localization to the tips of the growing root hairs in Arabidopsis thaliana. Using this tip-localized fusion protein, we demonstrate that all four proteins rapidly depolarize the growing root hair and block growth in a reversible manner. This inhibitory activity on root and root hair is not directly correlated with the antifungal activity of these proteins and suggests that plants apparently express targets for these antifungal proteins. The data presented here suggest that plant defensins may have roles in regulating plant growth and development.

Item Type: Article
Additional Information: This work was supported by a grant from the National Science Foundation (grant number 0344444 to DMS and TJS).
Uncontrolled Keywords: Plant defensin · Root · Root hair
Author Affiliation: The Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO 63132, USA.
Subjects: Plant Protection
Crop Improvement
Divisions: Other Crops
Depositing User: Mr Balakrishna Garadasu
Date Deposited: 04 Feb 2013 03:06
Last Modified: 04 Feb 2013 03:06
Official URL:

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