Expression of a Novel Small Antimicrobial Protein from the Seeds of Motherwort ( Leonurus japonicus ) Confers Disease Resistance in Tobacco

Abstract

Medicinal plants are valuable resources of natural antimicrobial materials. A novel small protein with antimicrobial activities, designated LJAMP1, was purified from the seeds of a medicinal herb, motherwort (Leonurus japonicus Houtt). LJAMP1 is a heat-stable protein with a molecular mass of 7.8 kDa and a determined isoelectric point of 8.2. In vitro assays showed that LJAMP1 inhibits the growth of an array of fungi and bacteria. The hyphal growth inhibition by LJAMP1 was more evident against hyphomycete fungi, such as Alternaria alternata, Cercospora personata, and Aspergillus niger. The N-terminal amino acid sequence of LJAMP1 was determined, and its coding gene was consequently cloned by the rapid amplification of cDNA ends. The gene LJAMP1 has no intron and encodes a polypeptide of 95 amino acids, in which the first 27 residues was deduced as a signal peptide. The mature LJAMP1 shows relatively low identity to plant napin-like storage proteins. Northern blot assays revealed that LJAMP1 is expressed preferentially in seeds. Bioassays in transgenic tobacco demonstrated that that overexpression of LJAMP1 significantly enhanced the resistance of tobacco against not only the fungal pathogen A. alternata but also the bacterial pathogen Ralstonia solanacearum, while no visible alteration in plant growth and development was observed.

Isolation of Antibacterial Protein/Peptide From Ficus Glomerata Leaf

“…Hence an attempt is made to explore the possible antimicrobial peptides generated through the medicinal plant. In previous studies, A 7.8 kDa of antimicrobial protein was isolated from the Seeds of Motherwort [28]. Similar to our study we found 35 kDa of protein isolated from Murraya Koenigii [29].…”

Expression and functional characterization of the plant antimicrobial snakin-1 and defensin recombinant proteins

“…Postharvest losses are estimated to range from 10% to 30% per year despite the use of modern storage facilities and new crop conservation techniques Recently the use of antimicrobial peptides, naturally produced by a variety of microorganisms and plants, was proposed for bioengineering and crop protection applications [6][7][8][9]. The decrease of susceptibility to pathogen infection as a result of transgenic production of antimicrobial agents in plants has been reported for thionins [10,11], lipid transfer proteins (LTPs) [12], defensins [13,14], snakins [15,16], and Leonurus japonicus antimicrobial protein (LJAMP1) [17], which have been isolated from such plants as: Vigna unguiculata, Arabidopsis thaliana, Medicago sativa, Raphanus sativus, Solanum tuberosum and Leonurus japonicus. The natural production of such antimicrobial proteins in plants is thought to be part of the constitutive or inducible defense mechanisms against pathogens acquired by plants in the course of evolution [18].…”

“…The decrease of susceptibility to pathogen infection as a result of transgenic production of antimicrobial agents in plants has been reported for thionins [10,11], lipid transfer proteins (LTPs) [12], defensins [13,14], snakins [15,16], and Leonurus japonicus antimicrobial protein (LJAMP1) [17], which have been isolated from such plants as: Vigna unguiculata, Arabidopsis thaliana, Medicago sativa, Raphanus sativus, Solanum tuberosum and Leonurus japonicus. The natural production of such antimicrobial proteins in plants is thought to be part of the constitutive or inducible defense mechanisms against pathogens acquired by plants in the course of evolution [18].…”

Plant antifungal proteins and their applications in agriculture

“…A 5-kDa peptide, Pe-AFP1, from passion fruit (P. edulis seeds) homologous to storage 2S albumins, inhibited development of the ilamentous fungi A. fumigatus, F. oxysporum, and Trichoderma harzianum, with IC50 values of 40, 34, and 32 μg/mL, respectively, but had no effect on C. albicans, Paracoccidioides brasiliensis, and Rhyzoctonia solani (Pelegrini et al 2006). Peptide LJAMP1 from motherwort (L. japonicus) seed extract with sequence homology to 2S albumins expressed antifungal activity against A. alternata, C. personata, and A. niger (Yang et al 2007). A heterodimeric 11.5-kDa Passiflora alata antifungal protein named Pa-AFP1, with marked homology to 2S albumins and composed of 4.5-and 7-kDa subunits, retarded the growth of the fungus C. gloeosporioides, but was inactive toward bacteria and yeasts (Ribeiro et al 2011).…”