Research Molecular Biologist USDA-ARS, Purdue University West Lafayette, Indiana, United States
The Hessian fly (Mayetiola destructor) belonging to the order Diptera (family: Cecidomyiidae), is an obligate destructive pest of host wheat (Triticum aestivum) causing severe economic losses. Wheat-Hessian fly interaction results in either incompatible interaction (resistant plant harboring H resistance gene; avirulent larvae) or compatible interaction (susceptible plant lacking resistance gene; virulent larvae). Insect virulence is characterized by up regulation of genes encoding (i) salivary effectors that alter and reprogram the host plant physiology; (ii) proteases, for proteolytic digestion; (iii) glycosylhydrolase, for breakdown plant cell wall; and (iv) detoxification enzymes to counter the plant allelochemicals in Hessian fly larvae allowing successful establishment of larval feeding sites. Virulent larval feeding on susceptible plant (i) triggers elevated expression of susceptibility genes; (ii) suppression of defense response genes; (ii) results in the formation of a nutritive tissue rich in amino acids, proteins, sugars, polyamines; and (iii) induces increased permeability making the plant a nutrient sink, benefitting the developing larvae. Understanding the mechanisms that insects employ to establish virulence and susceptibility can help in engineering strategies to aid economically important crop plants defend against this and other insect pests.
