Plants have developed complex defense mechanisms against pests and pathogen attack.  The diverse array of defense mechanisms includes the use of structural (cell wall) and biochemical defense (Hématy et al., 2009),  production of antimicrobial phytoalexins (van Etten et al., 1989; Hammerschmidt and Dann 1999), pathogenesis-related proteins (Linthorst, 1991; Ponstein et al., 1994; van Loon et al., 2006),  a large group of cysteine-rich proteins such as lipid transfer protein (Garcia-Olmedo et al., 1995), and plant defensins (Broekaert et al., 1995; Terras et al., 1995). Plant defensins are highly stable,  small cationic peptides of 45–54 amino acid residues, these cysteine-rich peptides can form three to four disulfide bridges. They constitute a part of the  innate defense system primarily directed against fungal pathogens. Broekaert et al. (1995) coined the term “plant defensin,” after comparison of a new class of plant antifungal peptides with known insect defensins. The first members of the family of plant defensins were isolated from wheat and barley grains (Colilla et al., 1990; Mendez et al., 1990). In Arabidopsis thaliana, at least 13 putative plant defensin genes (PDF) are present, encoding 11 different plant defensins (Thomma et al., 2002).

Defensins can be produced by plant, fungi, human, other mammals, birds, reptiles, fish, mollusks and  arthropods (Thomma et al., 2002; Wong et al., 2007; Carvalho and Gomesa 2009 ). Plant defensins and defensin-like peptides are functionally diverse, regulating plant growth and development, disrupting microbial membranes, acting as ligands for cellular recognition and signaling (Stotz et al., 2009a ; Stotz et al., 2009b; Okuda et al., 2009). Besides these  the  variety of functions attributed to plant defensins  include antifungal activity (Terras et al., 1995), antibacterial activity ( Zhang and Lewis 1997;  Segura et al., 1998) and inhibition of α-amylases and proteases (Bloch and Richardson 1991: Wijaya et al., 2000).

Plant defensins are best characterized in seeds  (Lay and Anderson 2005). During seed germination  the seed loses its seed coat protection and becomes vulnerable to soil microorganism.  Defensins being relatively abundant in seed tissue can protect seed from soil fungi resulting in enhanced seedling survival rate and apart from this  they can also protect plant from microbial infection (Terras et al., 1995; Carvalho and Gomesa 2009). In addition, plant defensins are also localized in the xylem, stomata, stomata cells, parenchyma cells, and other peripheral areas (Kragh et al., 1995; Segura et al., 1998; Chen et al., 2002).

Plant defensin NaD1 (from the flowers of Nicotiana alata) targets filamentous fungi, the interaction begins with the fungal cell wall, followed by permeabilization of the plasma membrane and subsequent entry of the defensin into the cytoplasm (van der Weerden  et al., 2008).  Defensins interact with fungal-specific lipid components in the plasma membrane. The structural differences between membrane of fungi and plant cells probably account for the selective action of plant defensins against fungal pathogens and being  nonphytotoxic (Thevissen et al., 2003).

Plant defensins show a constitutive pattern of expression in response to pathogen attack, injury and abiotic stresses (Bahramnejad et al., 2009;  de Beer and Vivier, 2011). Antimicrobial microbial peptides (AMPs) display resistance against bacteria, fungi and viruses. In plant eight main classes of  AMPs are cyclotides, lipid transfer proteins, defensins, thionins, snakins, hevein-like, vicilin-like, and knottins (Goyal and Mattoo, 2014).  Variety of function attributed to plant defensin  shows its possibility to be used as a commercial product in suppression of pathogens.



Bahramnejad,  B.,  Erickson, L. R.,  Chuthamat,  A. and   Goodwin,  P. H.  2009  Differential Expression of Eight Defensin Genes of N. benthamiana Following Biotic Stress, Wounding, Ethylene, and Benzothiadiazole Treatments. Plant Cell Rep. 28 (4): 703-717


Bloch, C. and Richardson, M. 1991 A New Family of Small (5 kDa) Protein Inhibitors of Insect α-Amylases from Seeds or Sorghum (Sorghum bicolor (L) Moench) have Sequence Homologies with Wheat γ-Purothionins. FEBS Lett. 279(1): 101 – 104

doi: 10.1016/0014-5793(91)80261-Z

Broekaert, W. F., Terras, F. R. G., Cammue, B. P. A. and  Osborn R. W. 1995 Plant Defensins: Novel Antimicrobial Peptides as Components of the Host Defense System.  Plant Physiol. 108(4): 1353–1358

Carvalho Ade, O. and  Gomes, V. M. 2009 Plant Defensins–Prospects for the Biological Functions and Biotechnological Properties. Peptides  30(5): 1007-20

 doi: 10.1016/j.peptides.2009.01.018

Chen K-C., Lin C-Y., Chung M – C., Kuan C-C., Sung H-Y., Tsou S. C. S.,  Kuo, C. G. and Chen, C-S.  2002 Cloning and Characterization of a cDNA Encoding an Antimicrobial Protein from Mung Bean Seeds. Bot. Bull. Acad. Sin. 43: 251–259

Colilla,  F. J.,  Rocher,  A. and  Mendez, E. 1990 Gamma-Purothionins: Amino Acid Sequence of Two Polypeptides of a New Family of Thionins from Wheat Endosperm. FEBS Lett. 270(1-2): 191-194

doi: 10.1016/0014-5793(90)81265-P

de Beer, A. and  Vivier, M. A. 2011 Four Plant Defensins from an Indigenous South African Brassicaceae Species Display Divergent Activities Against Two Test Pathogens Despite High Sequence Similarity in the Encoding Genes. BMC Res. Notes 4:459


Garcia-Olmedo, F., Molina, A., Segura, A. and Moreno, M. 1995  The Defensive Role of Nonspecific Lipid-Transfer Proteins in Plants. Trends Microbiol. 3: 72-74

Goyal,  R. K. and Mattoo, A. K. 2014 Multitasking Antimicrobial Peptides in Plant Development and Host Defense Against Biotic/Abiotic Stress. Plant Sci. 228: 135 – 149

Hammerschmidt, R. and Dann, E. K. 1999 The Role of Phytoalexins in Plant Protection. Novartis Found Symp. 223: 175-87

Hématy, K., Cherk, C. and Somerville, S. 2009 Host-Pathogen Warfare at the Plant Cell Wall. Curr. Opin.  Plant Biol. 12(4): 406-413

doi: 10.1016/j.pbi.2009.06.007

Kragh,  K. M., Nielsen, J. E., Nielsen, K. K., Dreboldt,  S. and Mikkelsen, J. D. 1995 Characterization and Localization of New Antifungal Cysteine-Rich Proteins from Beta vulgaris. Mol. Plant Microbe Interact. 8(3): 424–434


Lay, F. T. and  Anderson,  M. A. 2005 Defensins–Components of the Innate Immune System in Plants. Curr.  Protein Pept.  Sci. 6(1): 85-101

doi: 10.2174/1389203053027575

Linthorst, H. J. M.  1991 Pathogenesis-Related Proteins of Plants. Crit. Rev. Plant Sci. 10: 123-150

Mendez,  E., Moreno,  A.,  Colilla,  F.,  Pelaez,  F.,  Limas, G. G.,  Mendez,  R., Soriano, F., Salinas, M. and  de Haro,  C. 1990 Primary Structure and Inhibition of Protein Synthesis in Eukaryotic Cell-Free System of a Novel Thionin, Gamma-Hordothionin, from Barley Endosperm. Eur. J Biochem. 194(2): 533-539

doi: 10.1111/j.1432-1033.1990.tb15649.x

Okuda, S., Tsutsui, H., Shiina, K., Sprunck, S., Takeuchi, H., Yui, R., Kasahara, R. D., Hamamura, Y., Mizukami, A., Susaki, D., Kawano, N., Sakakibara, T., Namiki, S., Itoh, K., Otsuka, K., Matsuzaki, M., Nozaki, H., Kuroiwa, T., Nakano, A., Kanaoka, M. M., Dresselhaus, T., Sasaki, N. and  Higashiyama,  T. 2009 Defensin-Like Polypeptide LUREs are Pollen Tube Attractants Secreted from Synergid Cells. Nature  458(7236): 357-61

 doi: 10.1038/nature07882

Ponstein, A. S., Bres-Vloemans, S. A., Sela-Buurlage, M. B.,  van den Elzen, P. J. M., Melchers, L. S. and Cornelissen,  B. J. C. 1994 A Novel Pathogen- and Wound-Inducible Tobacco (Nicotiana tabacum) Protein with Antifungal Activity. Plant Physiol. 104(1): 109-118

Stotz, H. U., Thomson, J. G. and Wang,  Y. 2009a  Plant Defensins. Plant Signal Behav. 4(11): 1010–1012

Stotz, H. U., Spence, B. and  Wang, Y. 2009b A Defensin from Tomato with Dual Function in Defense and Development. Plant Mol. Biol. 71(1-2):131-43

 doi: 10.1007/s11103-009-9512-z

Segura, A., Moreno, M., Molina, A. and  Garcia-Olmedo, F.  1998  Novel Defensin Subfamily from Spinach (Spinacia oleracea). FEBS Lett 435(2-3):  159–162

doi: 10.1016/S0014-5793(98)01060-6

Terras, F. R.,  Eggermont,  K.,  Kovaleva, V.,  Raikhel,  N. V.,  Osborn,  R. W.,  Kester,  A.,  Rees,  S. B.,  Torrekens, S.,  Van Leuven,  F. and  Vanderleyden,  J. 1995    Small Cysteine-Rich Antifungal Proteins from Radish: their Role in Host Defense. Plant Cell  7(5): 573–588

Thevissen, K.,   Ferket,    K. K. A.,  .François,  I. E. J. A. and  Cammue, B. P. A. 2003 Interactions of Antifungal Plant Defensins with Fungal Membrane Components. Peptides 24(11):  1705-1712

Thomma, B.P., Cammue, B.P. A.  and  Thevissen, K.  2002 Plant Defensins. Planta 216(2): 193 – 202

van der Weerden,  N. L., Lay,  F. T. and  Anderson,  M. A. 2008 The Plant Defensin, NaD1, Enters the Cytoplasm of Fusarium oxysporum  Hyphae.  J. Biol. Chem. 283: 14445–14452

doi: 10.1074/jbc.M709867200

van Etten, H. D., Mattews, D. E. and Mattews,  P. S. 1989 Phytoalexin Detoxification: Importance for Pathogenicity and Practical Implications. Annu. Rev. Phytopath. 27: 143-164

van Loon, L. C., Rep, M. and Pieterse, C. M. J. 2006 Significance of Inducible Defense-Related Proteins in Infected Plants. Ann.  Rev.  Phytopathol.  44: 135-162

Wong,  J. H.,  Xia, L. and  Ng, T. B. 2007 A Review of Defensins of Diverse Origins. Curr.  Protein Pept.  Sci. 8(5): 446-459

doi : 10.2174/138920307782411446

Wijaya, R., Neumann, G. M., Condron,  R., Hughes,  A. B. and  Polya,  G. M. 2000 Defense Proteins from Seed of Cassia fistula Include a Lipid Transfer Protein Homologue and a Protease Inhibitory Plant Defensin. Plant Sci. 159(2): 243-255

Zhang,  Y. and   Lewis,  K. 1997  Fabatins: New Antimicrobial Plant Peptides. FEMS Microbiol. Letters 149(1):  59–64

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s