Resistance to Anticarsia gemmatalis Hübner (Lepidoptera, Noctuidae) in transgenic soybean (Glycine max (L.) Merrill Fabales, Fabaceae) cultivar IAS5 expressing a modified Cry1Ac endotoxin

Abstract

Somatic embryos of the commercial soybean (Glycine max) cultivar IAS5 were co-transformed using particle bombardment with a synthetic form of the Bacillus thuringiensis delta-endotoxin crystal protein gene cry1Ac, the β-glucuronidase reporter gene gusA and the hygromycin resistance gene hpt. Hygromycin-resistant tissues were proliferated individually to give rise to nine sets of clones corresponding to independent transformation events. The co-bombardment resulted in a co-transformation efficiency of 44%. Many histodifferentiated embryos and 30 well-developed plants were obtained. Twenty of these plants flowered and fourteen set seeds. The integration and expression of the cry1Ac, gusA and hpt transgenes into the genomes of a sample of transformed embryos and all T 0 , T 1 , T 2 and T 3 plants were confirmed by Gus activity, PCR, Southern and western blot, and ELISA techniques. Two T 0 plants out of the seven co-transformed plants produced seeds and were analyzed for patterns of integration and inheritance until the T 3 generation. Bioassays indicated that the transgenic plants were highly toxic to the velvetbean caterpillar Anticarsia gemmatalis, thus offering a potential for effective insect resistance in soybean.

Agronomic performance, chromosomal stability and resistance to velvetbean caterpillar of transgenic soybean expressing cry1Ac gene

“…The transgenic progenies of the cultivar IAS 5, analyzed in this study, were developed by Homrich et al (2008) and carry the synthetic cry1Ac, hpt and gusA genes. The cry1Ac gene is truncated in the C terminus region and harbors the intact N terminus region of the native gene (Sardana et al, 1996).…”

“…A transgenic homozygous line harboring only gusA reporter gene, obtained in the previous work (Homrich et al, 2008), was used as a negative control in the bioassays. This gusA line was likely derived by interchromosomal recombination from transformants, which contained cry1Ac, hpt and gusA genes integrated at a single locus.…”

“…The T 3 homozygous plants resulted from the same transformation event (Homrich et al, 2008). The progenies identified by the numbers 44,46,162,169,438,497,507,520,551,937,1274 were evaluated for their agronomic performance.…”

“…In a previous study, Homrich et al (2008) developed an 'IAS 5' transgenic line containing an intact copy of a truncated synthetic cry1Ac gene from B. thuringiensis. A preliminary in vitro insect feeding assay indicated that transgenic plants were highly toxic to A. gemmatalis larvae.…”

Strategies for Improvement of Soybean Regeneration via Somatic Embryogenesis and Genetic Transformation

“…Even after more than two decades, the stable transformation of soybean cannot yet be considered as routine because it depends on the ability to bring together efficient transformation and regeneration techniques. Two methods have been successfuly used: particle bombardment Finer & McMullen, 1991;Christou & McCabe, 1992;Finer et al, 1992;Stewart et al, 1996;Aragão et al, 2000;Droste et al, 2002;Homrich et al, 2008;Wu et al, 2008;Li et al, 2009;Hernandez-Garcia et al, 2009;Xing et al, 2010;Viana et al, 2011) and Agrobacterium tumefaciens system Trick & Finer, 1998;Aragão et al, 2000;Yan et al, 2000;Ko et al, 2003Ko et al, , 2004Paz et al, 2006;Hong et al, 2007;Miklos et al, 2007;Liu et al, 2008;Wang & Xu, 2008;Wiebke-Strohm et al, 2011).…”