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Abstract: Plant defensins are small, basic cysteine-rich peptides ranging from 45 to 54 amino acids and are positively charged. They are a part of the innate immune system and possess antifungal and/or antibacterial activities found in many plant species, including Brassica family. Brassica juncea has been known as a nutritional vegetable, medicinal plant species and an oilseed crop in many countries. It has also been reported to be heat- and drought-tolerant and resistant to fungal diseases. This study aimed to isolate and characterize the BjAFP defensins genes from Vietnamese B. juncea. As the result, three nucleotide sequences of defensins genes were amplified, including BjAFP1, BjAFP4-like and an unpublished gene called BjAFPx. By comparison of DNA sequences from PCR and RT-PCR products, the result showed that, each gene consisted of one intron and two exons. Two exons had respectively 64 nucleotides and 179 nucleotides while intron contains 91 nucleotides in BjAFP1, 93 nucleotides in BjAFP4 and 98 nucleotides in BjAFPx. Besides, gene BjAFP1 expressed at transcription level in all tissues: stem, root, leaf, flower and seed of B. juncea. In comparison of the nucleotide sequence of BjAFP1 with two published sequences of this gene in Genbank, the single nucleotide polymorphisms in BjAFP1 have been identified, including one missense substitution at position 54 in nucleotide sequence, which replcaed amino acid phenylalanine by leucine, and three synonymous at positions 51, 204 and 225 in nucleotide sequence.Keywords: Brassica juncea, defensin, BjAFP1, BjAFP4, BjAFPx.
 Van der Weerden N. L., M. R. Bleackley and M. A. Anderson, “Properties and mechanisms of action of naturally occurring antifungal peptides”, Cell Mol Life Sci., 70(19) (2013), 3545-3570.
 Broekaert W. F., F. R. Terras, B. P. Cammue and R. W. Osborn, “Plant defensins: novel antimicrobial peptides as components of the host defense system”, Plant Physiol, 108(4) (1995), 1353-1358.
 Carvalho Ade O., Gomes V. M., “Plant defensins-prospects for the biological functions and biotechnological properties”, Peptides, 30(5) (2009), pp. 1007-1020.
 Thomma BPHJ, Thevissen K, Cammue BP. Plants defensins. Planta; 216 (2002), 193-202.
 Almeida MS, Cabral KM, Kurtenbach E, Almeida FC, Valente APJX. Solution structure of Pisum sativum defensin 1 by high resolution NMR: plant defensins, identical backbone with different me-chanisms of action. Mol Biol.; 315 (2002), 749-57.
 Hanks JN, Snyder AK, Graham MA, Shah RK, Blaylock LA, Harrison MJ, Shah DM: Defensin gene family in Medicago truncatula: structure, expression and induction by signal molecules. Plant Mol Biol, 58(3) (2005, 385-399.
 Gao AG, Hakimi SM, Mittanck CA, Wu Y, Woerner BM, Stark DM, Shah DM, Shah DM, Liang J, Rommens CM. Fungal pathogen protection in potato by expression of a plant defensin peptide. Nat Biotechnol 2000; 18:1307-10.
 Swathi A.T., Jami S.K. and Kirti P. B., “A defensin gene of Indian mustard is stress induced”, Journal of Plant Biochemistry and Biotechnology, 18(2) (2009), 221-224.
Hombergen E. J., Bachmann K., “RAPD mapping of three QTLs determining trichome formation in Microseris hybrid H27 (Asteraceae: Lactuceae)”, Theoretical and Applied Genetics, 90(6) (1995), 853-858.