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Title: RESISTANCE COMPONENTS OF P.I. 240675 RYE TO BIOTYPE F GREENBUG

Author
item CURVETTO, RUDOLFO - I.N.T.A., ARGENTINA
item Webster, James

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The greenbug is a serious aphid pest of small grains and sorghum, especially on the Southern Plains of the United States. The use of greenbug-resistant varieties is an ideal management strategy for this insect. Plant breeders and entomologists have developed varieties and germplasm lines that are resistant to this pest, but some of their efforts have been thwarted by new greenbug biotypes that damage these resistant entries. Therefore, researchers are constantly searching for new sources of greenbug resistance. Previous research identified a rye accession, P.I. 240675, as resistant to biotype F of the greenbug. This was significant because Dickinson 28A is the only hexaploid wheat source of resistance to biotype F. However, this wheat is susceptible to all other biotypes. Although biotype F is most often found on bluegrass, it is important to locate and study additional sources of biotype F resistance for wheat because this biotype will damage wheat also. The purpose of this research was to select biotype F-resistant seedlings of P.I. 240675 and to compare components or types of resistance of this entry with those of Insave F.A. rye and Century wheat. Insave F.A. and Century are resistant to biotypes B and C, and Century's resistance is derived from Insave F.A. The results from all test showed that P.I. 240675 exhibited the highest level of resistance of the three entries in the study. P.I. 240675 is resistant to all important biotypes on wheat (biotypes, B, C, E, F, and G) and is thus a good source of greenbug resistance for rye and species related to and crossable with rye, including wheat.

Technical Abstract: Dickinson Selection 28A is the only hexaploid wheat source of resistance to biotype F greenbug, Schizaphis graminum (Rondani). However, this wheat is susceptible to all other greenbug biotypes. Although biotype F is found most often on bluegrass, it is important to locate additional sources of biotype F resistance for wheat, because this biotype can also damage wheat. .Previous research identified a rye accession, P.I. 240675, as resistant to biotype F. Rye is crossable with wheat and is frequently utilized by breeders in wheat improvement programs. The purpose of this research was to select biotype F-resistant seedlings of P.I. 240675 and to compare components of resistance of P.I. 240675 with those of Insave F.A. rye and Century wheat. The results from all tests showed that P.I. 240675 exhibited the highest level of resistance of the three entries in the study, and had a relatively high degree of all three components of resistance. Although antibiosis to biotype F was detected in Insave F.A., this entry had low levels of tolerance and antixenosis and is not a good source of biotype F resistance for breeding programs. An additional test showed that P.I. 240675 is also resistant to biotype G. P.I. 240675 is thus resistant to biotypes B, C, E, F, and G and can be used as a source of resistance to these biotypes in rye and species related to and crossable with rye, including wheat.