Areas of Expertise:
avirulence, insects as plant pathogens
Hessian Fly, HF , Mayetiola destructor, Diptera Cecidomyiidae, gall midge, Sogata, Tagosodes orizicolus, hoja blanca virus (RHBV),
Dr. Stuart's research is largely focused on the molecular genetics of plant-insect interactions. Currently, it is centered on understanding the mechanisms that allow plant-galling arthropods to create galls on plants and testing the hypothesis that arthropod-produced effector proteins have evolved to create the extended phenotypes we call plant galls. Toward that goal, we have been improving the Hessian fly (HF, Mayetiola destructor), one of the most economically important gall midges, as a genetically tractable experimental organism for studies of plant-insect interactions and arthropod-induced plant-gall formation. Recent efforts have sequenced and assembled the HF genome and ordered approximately 60% of the sequence on the HF chromosomes. Over 1500 putative effector genes have been identified in the HF genome and five candidate Avr-effectors have been genetically identified. We are currently developing methods that will allow us to understand the function of the proteins these genes encode in both HF-susceptible and HF-resistant germplasm.
A recent sabbatical leave to the International Center of Tropical Agriculture (CIAT) in Palmira, Colombia allowed Dr. Stuart to explore the biology of another important cereal pest, a plant hopper called Sogata (Tagosodes orizicolus), the major vector of rice hoja blanca virus (RHBV). Previous investigations indicated that a single Medelian factor conditions RHBV-virulence and RHBV-avirulence and that avirulence is dominant to virulence. To test this hypothesis, structured Sogata mapping populations were developed so that bulked segregant analysis, in combination with whole genome sequencing of Sogata RHBV-virulent and RHBV-avirulent bulks, can be performed. Results of these experiments are expected to provide a first draft of the Sogata genome and the discovery of what causes viral incompetence in the insect.
Current Research Projects
- Association mapping mutations in the Hessian fly that confer virulence to resistance genes H5, H3, and H6 in wheat
- Improved Hessian fly genome assembly and annotation
- Population genetics of fitness costs of H13-virulence
- Development of functional assays for putative effector proteins
- Mechanisms and evolution of monogenic sex determination in the Hessian fly
- Mechanisms of Sogata vector competence and RHBV transmission