Development of multiple insect resistance in tropical and subtropical maize represents a major effort of the maize breeding program at CIMMYT. Resistance to the southwestern corn borer (SWCB), an aggressive feeder, appears to be polygenically controlled and has been widely considered to involve primarily additive gene action. Some of the components of resistance to SWCB seem to confer resistance to other important Lepidopteran maize pests, including the sugar cane borer (SCB). Our objective was to map, using restriction fragment length polymorphism (RFLP) markers, the quantitative trait loci (QTL) involved in the resistance to SWCB and SCB as a first step towards the use of marker-assisted selection in the breeding for such complex traits. Two distinct F2 populations were developed, each from a cross between a susceptible (S) and a resistant (R) line: the population derived from the Ki3 (S) and CML139 (R) cross was comprised of 476 F2 individuals and was evaluated for SWCB. The population derived from the CML131 (S) and CML67 (R) cross consisted of 215 individuals and was rated for SWCB and SCB. F2 individuals were genotyped using close to 100 genomic and cDNA maize probes. F3families were rated for leaf-feeding damage (1-10 scale) after artificial infestation for two or three consecutive years at one or two locations. The QTL analyses were conducted using single-factor ANOVAs and a maximum likelihood approach (MAPMAKER/QTL). Several chromosomal regions were found to be involved in the resistance to SWCB and SCB. Not all regions were shared by the two populations for SWCB and some QTL were common in the resistance to both insects. Most of the QTL showed additive and dominance effects.

English

9711|AGRIS 9702|anterior|R97-98PROCE|FINAL9798

Jose Juan Caballero

CIMMYT Publications Collection