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Host race evolution in Schizaphis graminum (Hemiptera: Aphididae): nuclear DNA sequences

Permanent URL:
http://handle.nal.usda.gov/10113/58244
File:
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Abstract:
The greenbug aphid, Schizaphis graminum (Rondani) was introduced into the US in the late 1880s and it established quickly as a pest on wheat, oat and barley. Sorghum was also a host, but it was not until 1968 that greenbug became a serious pest on it. The most effective control method is the planting of resistant varieties; however, the occurrence of greenbug biotypes has hampered the development and use of plant resistance as a management technique. Until the 1990s, the evolutionary status of greenbug biotypes was obscure. Four mtDNA cytochrome oxidase subunit I (COI) haplotypes were previously identified, suggesting that S. graminum sensu lato was comprised of host-adapted races. To elucidate the current evolutionary and taxonomic status of the greenbug and its biotypes, two nuclear genes and introns were sequenced; cytochrome c (CytC) and elongation factor 1-alpha (EF1-alpha). Phylogenetic analysis of CytC sequences were in complete agreement with COI sequences and demonstrated three distinct evolutionary lineages in S. graminum. EF1-alpha DNA sequences were in partial agreement with COI and CytC sequences, and demonstrated two distinct evolutionary lineages. Host-adapted races in greenbug are sympatric and appear reproductively isolated. Agricultural biotypes in S. graminum likely arose by genetic recombination via meiosis during sexual reproduction within host-races. The 1968 greenbug outbreak on sorghum was the result of the introduction of a host race adapted to sorghum, and not selection by host resistance genes in crops.
Author(s):
Kevin A. Shufran
Subject(s):
Hemiptera , Schizaphis graminum , Sorghum (Poaceae) , biotypes , coevolution , crops , cytochrome c , cytochrome-c oxidase , evolutionary adaptation , genes , genetic recombination , haplotypes , host plants , insect pests , insect taxonomy , introns , meiosis , mitochondrial DNA , natural selection , nuclear genome , pest resistance , phylogeny , plant genetic resources , plant pests , plant-insect relations , races , resistance mechanisms , sequence analysis , sexual reproduction , United States
Source:
Environmental entomology 2011 10 1 v.40 no.5
Language:
English
Year:
2011
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.