Abstract
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.
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Abbreviations
- RabA4b:
-
Rab GTPase
- EYFP:
-
Enhanced yellow fluorescent protein
- MES:
-
2-(4-Morpholino)-ethane sulfonic acid
References
Bibikova TN, Zhigilei A, Gilroy S (1997) Root hair growth in Arabidopsis thaliana is directed by calcium and an endogenous polarity. Planta 203:495–505
Boller T (2005) Peptide signaling in plant development and self/non-self perception. Curr Opin Cell Biol 17:116–122
Broekaert WF, Terras FR, Cammue BP, Osborn RW (1995) Plant defensins: novel antimicrobial peptides as components of the host defense system. Plant Physiol 108:1353–1358
Casamitjana-Martinez E, Hofhuis HF, Xu J, Liu CM, Heidstra R, Scheres B (2003) Root-specific CLE19 overexpression and the sol1/2 suppressors implicate a CLV-like pathway in the control of Arabidopsis root meristem maintenance. Curr Biol 13:1435–1441
Coca M, Bortolotti C, Rufat M, Penas G, Eritja R, Tharreau D, del Pozo AM, Messeguer J, San Segundo B (2004) Transgenic rice plants expressing the antifungal AFP protein from Aspergillus giganteus show enhanced resistance to the rice blast fungus Magnaporthe grisea. Plant Mol Biol 54:245–259
da Silva Conceicao A, Broekaert WF (1999) Plant defensins. In: Datta SK, Muthukrishnan S (eds) Pathogenesis-related proteins in plants. CRC, New York, pp 247–260
de Zélicourt A, Letousey P, Thoiron S, Campion C, Simoneau P, Elmorjani K, Marion D, Simier P, Delavault P (2007) Ha-DEF1, a sunflower defensin, induces cell death in Orobanche parasitic plants. Planta (in press)
Dolan L, Duckett CM, Grierson C, Linstead P, Schneider K, Lawson E, Dean C, Poethig S, Roberts K (1994) Clonal relationships and cell patterning in the root epidermis of Arabidopsis. Development 120:2465-2474
Felle HH, Hepler PK (1997) The cytosolic Ca2+ concentration gradient of Sinapis alba root hairs as revealed by Ca2+-selective microelectrode tests and fura-dextran ratio imaging. Plant Physiol 114:39–45
Fletcher JC, Brand U, Running MP, Simon R, Meyerowitz EM (1999) Signaling of cell fate decisions by CLAVATA3 in Arabidopsis shoot meristems. Science 283:1911–1914
Gage MJ, Bruenn J, Fischer M, Sanders D, Smith TJ (2001) KP4 fungal toxin inhibits growth in Ustilago maydis by blocking calcium uptake. Mol Microbiol 41:775–786
Gage MJ, Rane SG, Hockerman GH, Smith TJ (2002) The virally encoded fungal toxin KP4 specifically blocks L-type voltage-gated calcium channels. Mol Pharmocol 61:936–944
Gao A, Hakimi SM, Mittanck CA, Wu Y, Woerner MB, Stark DM, Shah DM, Liang J, Rommens CMT (2000) Fungal pathogen protection in potato by expression of a plant defensin peptide. Nat Biotechnol 18:1307–1310
Gu F, Khimani A, Rane SG, Flurkey WH, Bozarth RF, Smith TJ (1995) Structure and function of a virally encoded fungal toxin from Ustilago maydis: a fungal and mammalian Ca2+ channel inhibitor. Structure 3:805–814
Hanks JN, Snyder AK, Graham MA, Shah RK, Blaylock LA, Harrison MJ, Shah DM (2005) Defensin gene family in Medicago truncatula: structure, expression and induction by signal molecules. Plant Mol Biol 58:385–399
Harold FM (1990) To shape a cell: an inquiry into the causes of morphogenesis of microorganisms. Microbiol Rev 54:381–431
Heath IB (1990) Tip growth in plant and fungal cells. Academic, San Diego
Hoffmann JA, Kafatos FC, Janeway CA, Ezekowitz RA (1999) Phylogenetic perspectives in innate immunity. Science 284:1313–1318
Hyde GJ, Heath IB (1995) Ca2+-dependent polarization of axis establishment in the tip-growing organism, Saprolegnia ferax, by gradients of the ionophore A23187. Eur J Cell Biol 67:356–362
Jackson SL, Heath IB (1993) The role of calcium ions in hyphal tip growth. Microbiol Rev 57:367–382
Koltin Y, Day PR (1975) Specifity of Ustilago maydis killer proteins. Appl Microbiol 30(4):694–696
Lehrer RI, Ganz T (2002) Defensins of vertebrate animals. Curr Opin Immunol 14:96–102
Lenhard M, Laux T (2003) Stem cell homeostasis in the Arabidopsis shoot meristem is regulated by intercellular movement of CLAVATA3 and its sequestration by CLAVATA1. Development 130:3163–3173
Matsubayashi Y, Sakagami Y (1996) Phytosulfokine, sulfated peptides that induce the proliferation of single mesophyll cells of Asparagus officinalis. Proc Natl Acad Sci USA 93:7623–7627
Mirouze M, Sels J, Richard, Czernic P, Loubet S, Jacquier A, Francois IEJA, Cammue BPA, Lebrun M, Berthomieu P, Marques L (2006) A putative novel role for plant defensins: a defensin from the zinc hyper-accumulating plant, Arabidopsis halleri, confers zinc tolerance. Plant J 47:329–342
Pearce G, Moura DS, Stratmann J, Ryan CA (2001) RALF, a 5-kDa ubiquitous polypeptide in plants, arrests growth and development. PNAS 98:12843–12847
Preuss ML, Serna J, Falbel TG, Bednarek SY, Nielsen E (2004) The Arabidopsis Rab GTPase RabA4b localizes to the tips of growing root hair cells. Plant Cell 16:1589–1603
Preuss ML, Schmitz AJ, Thole JM, Bonner HKS, Otegui MS, Nielsen E (2006) The PI-4K, PI-4Kβ1 is an effector of AtRabA4b and is involved in polarized tip-growth of root hair epidermal cells in Arabidopsis. J Cell Biol 172:991–998
Ramamoorthy V, Zhao X, Snyder AK, Xu JR, Shah DM (2007) Two mitogen-activated protein kinase signalling cascades mediate basal resistance to antifungal plant defensins in Fusarium graminearum. Cell Microbiol 9:1491–1506
Robson GD, Wiebe MG, Trinci APJ (1991) Involvement of Ca2+ in the regulation of hyphal extension and branching in Fusarium graminearum A 3/5. Exp Mycol 15:263–272
Rojo E, Sharma VK, Koaleva V, Raikhel NV, Fletcher JC (2002) CLV3 is localized to the extracellular space, where it activates the Arabidopsis CLAVATA stem cell pathway. Plant Cell 14:969–977
Ruiz Herrera J (1991) Fungal cell wall: structure, synthesis, and assembly. CRC, Boca Raton
Scheifelbein JW, Shipley A, Rowse P (1992) Calcium influx at the tip of growing root-hair cells of Arabidopsis thaliana. Planta 187:455–459
Schopfer CR, Nasrallah ME, Nasrallah JB (1999) The male determinant of self-incompatibility in brassica. Science 286:1697–1700
Shaw B, Hoch HC (2001) Ions as regulators of growth and development. In: Howard RJ, Gow NAR (eds) The mycota. Springer, Germany, pp 73–89
Spelbrink RG, Dilmac N, Allen A, Smith TJ, Shah DM, Hockerman GH (2004) Differential antifungal and calcium channel-blocking activity among structurally related plant defensins. Plant Physiol 135:2055–2067
Takayama S, Shiba H, Iwano M, Shimosato H, Che F-S, Kai N, Watanabe M, Suzuki G, Hinata K, Isogai A (2000) The pollen determinant of self-incompatibility in Brassica campestris. PNAS 97:1920–1925
Terras FR, Schoofs MM, De Bolle MF, Van Leuven F, Rees SB, Vanderleyden J, Cammue BP, Broekaert WJ (1992) Analysis of two novel classes of plant antifungal proteins from radish (Raphanus sativus L.) seeds. J Biol Chem 267:15301–15309
Thevissen K, Ghazi A, De Samblanx GW, Brownlee C, Osborn RW, Broekaert WF (1996) Fungal membrane responses induced by plant defensins and thionins. J Biol Chem 271:15018–15025
Thomma BPHJ, Camme BPA, Thevissen K (2002) Plant defensins. Planta 216:193–202
Trotochaud AE, Jeong S, Clark SE (2000) CLAVATA3, a multimeric ligand for the CLAVATA1 receptor-kinase. Science 289:613–617
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This work was supported by a grant from the National Science Foundation (grant number 0344444 to DMS and TJS).
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A. Allen and A.K. Snyder contributed equally.
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Allen, A., Snyder, A.K., Preuss, M. et al. Plant defensins and virally encoded fungal toxin KP4 inhibit plant root growth. Planta 227, 331–339 (2008). https://doi.org/10.1007/s00425-007-0620-1
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DOI: https://doi.org/10.1007/s00425-007-0620-1