Vijayan S, Guruprasad Lalitha, Kirti P B
Department of Plant Sciences, University of Hyderabad, Hyderabad, India.
Appl Microbiol Biotechnol. 2008 Oct;80(6):1023-32. doi: 10.1007/s00253-008-1648-2. Epub 2008 Aug 23.
Plant defensins are small, highly stable, cysteine-rich antimicrobial peptides produced by the plants for inhibiting a broad-spectrum of microbial pathogens. Some of the well-characterized plant defensins exhibit potent antifungal activity on certain pathogenic fungal species only. We characterized a defensin, TvD1 from a weedy leguminous herb, Tephrosia villosa. The open reading frame of the cDNA was 228 bp, which codes for a peptide with 75 amino acids. Expression analyses indicated that this defensin is expressed constitutively in T. villosa with leaf, stem, root, and seed showing almost similar levels of high expression. The recombinant peptide (rTvD1), expressed in the Escherichia coli expression system, exhibited potent in vitro antifungal activity against several filamentous soil-borne fungal pathogens. The purified peptide also showed significant inhibition of root elongation in Arabidopsis seedlings, subsequently affecting the extension of growing root hairs indicating that it has the potential to disturb the plant growth and development.
植物防御素是植物产生的一类小的、高度稳定的、富含半胱氨酸的抗菌肽，可抑制多种微生物病原体。一些已被充分表征的植物防御素仅对某些致病真菌物种表现出强大的抗真菌活性。我们从一种杂草豆科草本植物绒毛灰叶（Tephrosia villosa）中鉴定了一种防御素TvD1。该cDNA的开放阅读框为228bp，编码一个含有75个氨基酸的肽。表达分析表明，这种防御素在绒毛灰叶中组成型表达，叶、茎、根和种子中的表达水平几乎相似且都很高。在大肠杆菌表达系统中表达的重组肽（rTvD1）对几种丝状土传真菌病原体表现出强大的体外抗真菌活性。纯化后的肽还显著抑制了拟南芥幼苗的根伸长，随后影响了生长中的根毛伸长，表明它有可能干扰植物的生长和发育。
