Molecular genetics of chromosome elimination and sex determination in the Hessian fly.

摘要

The Hessian fly, Mayetiola destructor (Say), is an important insect pest of wheat, Triticum spp. Incorporating major Hessian fly resistance genes into wheat cultivars is the primary method of controlling this pest. However, genetic mutations in the Hessian fly have allowed certain genotypes to make this resistance ineffective. Therefore, greater knowledge of this insect's genetics is desirable. Two issues are central to this problem: (1) The anomalous mechanism of sex determination in the Hessian fly is poorly understood, and (2) there is an absence of a well characterized genetic map of the Hessian fly genome. My research addressed both problems. Sex determination in the Hessian fly was investigated using both bulked segregant analysis and individual females in a relatively large (N = 92) mapping population. This investigation discovered molecular genetic markers that are tightly linked to each other and an autosomal maternal effect gene (Chromosome maintenance , Cm) that appears to control X chromosome elimination among the offspring of individual females. During the course of this investigation, I found that a previously developed AFLP-based genetic map was useful. To improve its utility further, I used fluorescent in situ hybridization (FISH) to test its precision. The physical positions of selected markers on the map were located on the salivary gland polytene chromosomes of the Hessian fly. This work firmly established chromosome-linkage group correlations in the Hessian fly, and identified problems in the map. In the process, molecular markers that can be used to identify each Hessian fly chromosome were developed.