Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/22/2007
Publication Date: 12/30/2007
Citation: Scully, B.T. 2007. Shrunken 2 sweet corn breeding and selection for insect resistance [abstract]. In: Proc. of the International Conference on Sweet Corn Genetics, Breeding and Production, November 26-29, 2007, Guangzhou, China. p. 64.
Technical Abstract: The southeastern United States is one of the largest production areas for fresh market sweet corn in the country. The sub-temperate, subtropical and tropical climates of this region offer growers the opportunity to provide the market with a year-round supply of fresh sweet corn. Across this region, the fall armyworm (Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), corn earworm (Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and corn silk fly (Euxesta stigmatias Loew (Diptera: Ulidiidae) have caused severe damage to the developing ears of sweet corn. The fall armyworm and the corn earworm have been severe problems in all types of corn production throughout the southeastern states for nearly a century, while the corn silk fly is a more recent problem that has progressively worsened as it has migrated northward from southern Florida. It typically attacks only the silk and developing kernels of sweet corn. Because of the extraordinary returns commonly associated with sweet corn production there is essentially a “zero-tolerance” policy for ear damage, and this market requirement is used to justify elevated insecticide use particularly after silk emergence. The purpose of this research program was to identify germplasm that was jointly resistant to the fall armyworm and the corn silk fly and deploy that resistance into sweet corn. A set of lines/populations including Zapalote Chico 2451, MP-704, DDSB, GT-114, and CEW-R58 revealed superior levels of resistance to both the fall armyworm and corn silk fly. Resistance in Zapalote Chico 2451 is based on the maysin, a product of the flavanoid pathway that is produced in emergent silk and confers ear resistance based on antibiosis. The shrunken 2 gene was backcrossed into Zapalote Chico 2451 to produce shrunken 2 Zapalote Chico. Both lines along with sweet corn hybrids ‘Primetime’ and GSS-0966 were assayed for resistance to both the corn silk fly and fall armyworm. The Zapalote Chico lines displayed resistance to both insects, while GSS-0966, which expresses the CryIA(b) insecticidal protein conferred by the Bt11 gene only exhibited resistance to the fall armyworm. These results indicated that maysin produced by Zapalote Chico conferred ear resistance to multiple insects in different orders.