Transgenic rice plants expressing the snowdrop lectin gene (gna) exhibit high-level resistance to the whitebacked planthopper (Sogatella furcifera)

Abstract

Transgenic rice plants, expressing snowdrop lectin [Galanthus nivalis agglutinin (GNA)], obtained by Agrobacterium-mediated genetic transformation, were evaluated for resistance against the insect, the whitebacked planthopper (WBPH). The transgene gna was driven by the phloem-specific, rice-sucrose synthase promoter RSs1, and the bar was driven by the CaMV 35S promoter. In our previous study, the transgenic status of these lines was confirmed by Southern, Northern and Western blot analyses. Both the transgenes, gna and bar, were stably inherited and co-segregated into progenies in T1 to T5 generations. Insect bioassays on transgenic plants revealed the potent entomotoxic effects of GNA on the WBPH. Also, significant decreases were observed in the survival, development and fecundity of the insects fed on transgenic plants. Furthermore, intact GNA was detected in the total proteins of WBPHs fed on these plants. Western blot analysis revealed stable and consistent expression of GNA throughout the growth and development of transgenic plants. Transgenic lines expressing GNA exhibited high-level resistance against the WBPH. As reported earlier, these transgenics also showed substantial resistance against the brown planthopper and green leafhopper.

Functional Characterization of HFR1, a High-MannoseN-Glycan-Specific Wheat Lectin Induced by Hessian Fly Larvae

“…The insecticidal activity of Man-binding lectins has been demonstrated against a spectrum of insects, both in artificial diets supplemented with the lectins (Powell et al, 1993;Fitches et al, 2001) and also when insects feed on natural and transgenic plants expressing lectins (Gatehouse et al, 1996;Nagadhara et al, 2004;Sadeghi et al, 2008). The snowdrop lectin, GNA, is toxic to brown planthopper (Nilaparvata lugens; Powell et al, 1998;Tang et al, 2001) and tomato moth (Lacanobia oleracea) larvae (Fitches et al, 1997;Gatehouse et al, 1997Gatehouse et al, , 1999 as well as to several aphid species (Hilder et al, 1995;Rahbé et al, 1995;Gatehouse et al, 1996;Sauvion et al, 1996).…”

Plant‐insect interactions: what can we learn from plant lectins?

“…GNA was also detected on gut proteins and even in the hemolymph of some insects. It should be noted that these lectin concentrations taken in by predators or parasitoids will be rather low under field conditions since the lectin concentrations in honeydew of insects fed on transgenic plants were below detection level (Nagadhara et al, 2004).…”

“…It can be hypothesized that as soon as GNA-binding sites in the insect have been saturated, excess GNA-intake can be excreted in the honeydew. Nagadhara et al (2004) tested resistance against Sogatella furcifera by expressing GNA specifically in the phloem of transgenic rice plants. Survival of nymphs and fecundity of adults both dropped by 90%, feeding (as measured by honeydew production) decreased, and surviving nymphs suffered delayed development.…”

Production of transgenic rice plants expressing Dioscorea batatas tuber lectin 1 to confer resistance against brown planthopper

“…One of the promising genes is encoding mannose-binding protein such as snowdrop lectin (Galanthus nivalis agglutinin; GNA) and garlic leaf lectin (Allium sativum agglutinin from leaf; ASAL). Expression of GNA or ASAL in rice plants has been shown to confer substantial resistance to BPH, WBPH, and green rice planthopper in terms of increased insect mortality, retarded development and decreased fecundity (Rao et al 1998;Nagadhara et al 2003Nagadhara et al , 2004Saha et al 2006a; Yarashi et al 2008). Mannose-binding proteins, in general, are known to bind to mannose-containing glycoproteins in the mid-guts of insects, and inhibit growth and development (Sauvion et al 1996).…”

“…Acquisition of resistance against the planthopper-vectored virus can be expected in the transgenic rice plants expressing DB1. RSs1 promoter has the advantage of maximizing expression of the insecticidal protein at the site of attack by sap-sucking insects, while minimizing it elsewhere in plants (Shi et al 1994;Nagadhara et al 2003Nagadhara et al , 2004Saha et al 2006a, b). The T-DNA region of our current study is composed of all rice genes except for DB1 from Dioscorea batatas.…”