Transgenic cowpea (Vigna unguiculata) seeds expressing a bean α-amylase inhibitor 1 confer resistance to storage pests, bruchid beetles

Abstract

Cowpea is one of the important grain legumes. Storage pests, Callosobruchus maculatus and C. chinensis cause severe damage to the cowpea seeds during storage. We employ a highly efficient Agrobacterium-mediated cowpea transformation method for introduction of the bean (Phaseolus vulgaris) alpha-amylase inhibitor-1 (alphaAI-1) gene into a commercially important Indian cowpea cultivar, Pusa Komal and generated fertile transgenic plants. The use of constitutive expression of additional vir genes in resident pSB1 vector in Agrobacterium strain LBA4404, thiol compounds during cocultivation and a geneticin based selection system resulted in twofold increase in stable transformation frequency. Expression of alphaAI-1 gene under bean phytohemagglutinin promoter results in accumulation of alphaAI-1 in transgenic seeds. The transgenic protein was active as an inhibitor of porcine alpha-amylase in vitro. Transgenic cowpeas expressing alphaAI-1 strongly inhibited the development of C. maculatus and C. chinensis in insect bioassays.

Inactivation of allergens and toxins

“…Several new plant toxic proteins with insecticidal properties have potential in this respect [129][130][131] some of which are commonly found in foods we already eat (e.g. [132]) and we know how to inactivate them. A particular appealing strategy is the use of RNAi in plants to silence pest genes [133,134].…”

Vigna

“…Later, Chaudhary et al ( 2007 ) using the direct shoot regeneration protocol from the cotyledonary node explants improved the effi ciency of transformation from 0.1 % (reported by Popelka et al 2006 ) to 1.9 %. Recently, Solleti et al ( 2008 ) successfully introduced bean α-amylase inhibitor-1 ( α -AI -1 ) gene into cowpea to transfer bruchid ( Callosobruchus spp.) resistance.…”

Plant Proteinaceous α-Amylase and Proteinase Inhibitors and Their Use in Insect Pest Control

“…Several amylase inhibitors have been expressed in different plants. However the expression of -amylase inhibitors ( -AI) from scarlet runner bean (Phaseolus coccineus) and common bean (Phaseolus vulgaris) has been extremely protective in genetic modified plants, showing enhanced shelter against pea weevils (Shade et al, 1994;Schroeder et al, 1995), adzuki bean (Ishimoto et al, 1996), chickpea (Sarmah et al, 2004;Ignacimuthu et al, 2006, Campbell et al, 2011 and cowpea (Solleti et al, 2008). Furthermore, transgenic pea showed enhanced defense against the pea weevil Bruchus pisorum was shown under field conditions (Morton et al, 2000).…”