Does R gene resistance allow wheat to prevent plant growth effects associated with Hessian fly (Diptera: Cecidomyiidae) attack?
Resistance genes (R genes) are an important part of the plant's immune system. Among insects, the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), larva is the target of the greatest number of characterized R genes (H1-H32). The biochemical/molecular mechanism of R gene resistance to Hessian fly is not well understood. In the absence of an effective R gene, larvae caused extensive growth deficits (> 30 cm) in wheat seedlings. In the presence of one of three effective R genes, H6, H9, or H13, larvae caused small growth deficits (approximately 3-4 cm) in two leaves (third and fourth) that were actively growing during the first days of larval attack. After larvae died on R gene plants, the fifth leaf and tiller leaves exhibited small increases in growth (2-4 cm). Growth responses of susceptible and resistant plants diverged at a time when Hessian fly larvae were establishing a nutritive gall tissue at feeding sites. The results of this study support the hypothesis that R gene resistance cannot prevent initial larval attack, but, by stopping the formation of the larval gall, it prevents the most serious consequences of larval attack.
Anderson
K G
KG
Department of Entomology, College of Agriculture, North Dakota State University, Fargo ND 58105, USA. karin.anderson@ndsu.edu
Harris
M O
MO
D000818:Animals; D004175:Diptera / Q000502:physiology*; D005260:Female; D017343:Genes, Plant; D005838:Genotype; D006790:Host-Parasite Interactions / Q000235:genetics / Q000502:physiology; D007814:Larva / Q000502:physiology*; D018515:Plant Leaves / Q000469:parasitology; D011156:Population Density; D014908:Triticum / Q000235:genetics* / Q000469:parasitology / Q000502:physiology