Expression of BrD1, a Plant Defensin from Brassica rapa, Confers Resistance against Brown Planthopper (Nilaparvata lugens) in Transgenic Rices

Abstract

Plant defensins are small (5-10 kDa) basic peptides thought to be an important component of the defense pathway against fungal and/or bacterial pathogens. To understand the role of plant defensins in protecting plants against the brown planthopper, a type of insect herbivore, we isolated the Brassica rapa Defensin 1 (BrD1) gene and introduced it into rice (Oryza sativa L.) to produce stable transgenic plants. The BrD1 protein is homologous to other plant defensins and contains both an N-terminal endoplasmic reticulum signal sequence and a defensin domain, which are highly conserved in all plant defensins. Based on a phylogenetic analysis of the defensin domain of various plant defensins, we established that BrD1 belongs to a distinct subgroup of plant defensins. Relative to the wild type, transgenic rices expressing BrD1 exhibit strong resistance to brown planthopper nymphs and female adults. These results suggest that BrD1 exhibits insecticidal activity, and might be useful for developing cereal crop plants resistant to sap-sucking insects, such as the brown planthopper.

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

“…Several of these peptides have been overexpressed in crop species leading to disease resistant traits. The overexpression of BrD1, wasabi defensin and Rs-AFP2 have led to the engineering of disease resistant rice species [66,68,70,77], while the overexpression of AlfAFP1 yielded disease resistant potatoes at field trail level [65,82]. The overexpression of wasabi defensin in tomatoes also showed resistance towards necrotrophic pathogens [83].…”

“…In addition to these strong antimicrobial activities that established them as important agricultural biotechnology targets, some members also show activities important for medical applications, including protease inhibitory activity [23,72], anti cancer activity [61,73] and HIV inhibition [61,74-76]. Other agriculturally important activities include insecticidal activity [35,36,77,78], activity against parasitic plants [79] and heavy metal tolerance [80]. …”

The expression pattern of the Picea glauca Defensin 1 promoter is maintained in Arabidopsis thaliana, indicating the conservation of signalling pathways between angiosperms and gymnosperms*

“…For these reasons, enhanced disease resistance following defensin over-expression has been reported in potatoes, tomatoes, carrots, wheat, tobacco, melon, rice, Norway spruce, pine, and Arabidopsis (Terras et al , 1995; Wang et al , 1999; Gao et al , 2000; Parashina et al , 2000; Elfstrand et al , 2001; Kim et al , 2004; Choi et al , 2009; Ntui et al , 2010; Portieles et al , 2010; Li et al , 2011); this list may not be exhaustive. Plant defensin expression in various organs and treatments has been well studied in Arabidopsis (Kragh et al , 1995; Terras et al , 1995; Manners et al , 1998; Thomma and Broekaert, 1998).…”

Insect antimicrobial peptides and their applications

“…Plant defensins have been expressed in transgenic rice (Choi et al, 2009; Jha and Chattoo, 2010), wheat (Li et al, 2011), banana (Ghag et al, 2012), tomato (Abdallah et al, 2010; Portieles et al, 2010), “Egusi” melon (Ntui et al, 2010), peanut (Swathi Anuradha et al, 2008), tobacco (Portieles et al, 2010; Swathi Anuradha et al, 2008), and Arabidopsis (Kaur et al, 2012). Transgenic expression of an insect defensin ( G. mellonella gallerimycin) and cecropin (sarcotoxin-IA) in tobacco also confers resistance to pathogenic fungi (Mitsuhara et al, 2000; Ohshima et al, 1999).…”