Submitted to: Crop Science
Publication Type: Germplasm Release
Publication Acceptance Date: December 31, 1998
Publication Date: N/A
Interpretive Summary: Germplasm registration article; no new research reported.
Technical Abstract: STARS-9577B is a 6-rowed, spring barley developed by USDA-ARS as a source of resistance to Russian wheat aphid (RWA). This line is a selection out of CI 4165, originally collected by N.I. Vavilov in 1924 as a landrace from Heart, Afghanistan. Although this accession appeared fairly homogeneous for RWA resistance, potential segregation for RWA-resistant genes necessitated screening and selection of 10 plants on the basis of RWA resistance and uniform agronomic appearance. Progeny of selected plants were rescreened before seed was bulked for release. STARS-9577B was highly resistant to the RWA in greenhouse tests of seedling plants using greenhouse-reared RWA. STARS-9577B rated 3 (Webster's scale), while susceptible cultivars such as Morex rated 9. This resistance persisted when plants were grown to maturity in the greenhouse under constant RWA infestation where aphid populations built up to levels 100 times greater than natural field infestations. In a 2-year field experiment in Wyoming under artificial RWA infestations, grai yield of STARS-9577B was not reduced, while susceptible check Morex suffered a 60% loss. Leaves of STARS-9577B do not streak or roll in response to RWA, and therefore plant damage and yield reduction due to chlorosis and head trapping do not occur. Genetic analysis of parent, F1, F2, BC, and F2-derived F3 populations of the cross Morex/STARS-9577B indicated 2 genes controlled RWA resistance in this line. Chi-square analysis suggests RWA resistance is conferred by 2 dominate genes with recessive epistasis. STARS-9577B resembles Morex in plant height and is 1 wk later than Morex in maturity in greenhouse studies and field tests, ranging from Colorado to Canada. Tolerance to RWA feeding is the main resistance mechanism in STARS-9577B, but some antibiosis was also detected.