Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 8/6/1997
Publication Date: N/A
Technical Abstract: The greenbug is a serious pest affecting small grains in central and southwestern United States. First reported in Virginia in 1882, its periodic outbreaks have resulted in millions of dollars in damage. Insecticide usage is limited by high cost and ineffectiveness; cultural and biological control methods also are not widely implemented. Development of greenbug-resistant varieties offers the best solution to the problem. Presently, our understanding of the mechanism of plant resistance to greenbug is still in its infancy. We reasoned that a rigorous examination of the mechanism involved in resistance may provide useful tools for developing new varieties via traditional plant breeding or by new plant transformation methods. Thus, we examined the induction of defense-related genes in susceptible and resistant isolines of barley in response to virulent and avirulent greenbug. The near-isolines that we used differ only yby the presence of the greenbug-resistance gene Rsgla. This gene confers resistance to 9 biotypes of greenbug. At the 3-leaf stage both resistant and susceptible isolines were either infested with biotype E or maintained as a non-infested control. Infested and control plants were maintained under identical conditions in separate growth chambers. Total RNA isolated from harvested tissue at various times following infestation was used to examine the induction of genes that may be involved in resistance to greenbug. Some of the defense-related genes under investigation include: thionins, a thaumatin-like protein, wound-induced protein kinases, peroxidases, gluthione-S-transferase, hydroxyproline-rich glycoproteins, ubiquitin, lipoxygenases, heat shock proteins, proteinase inhibitors, and core enzymes of phenylpropenoid metabolism.