Molecular mapping of sorghum genes expressing tolerance to damage by greenbug (Homoptera: Aphididae).
Genetic linkage maps are fundamental for the localization of genes conferring tolerance to greenbug, Schizaphis graminum (Rondani), feeding damage in sorghum, Sorghum bicolor (L.) Moench. Thirteen linkage groups (LGs) containing 60 simple sequence repeat (SSR) loci were mapped by using a set of sorghum recombinant inbred lines (RILs) obtained from the cross '96-4121' (greenbug-tolerant parent) x Redlan (greenbug-susceptible parent). The LG spanned a distance of 603.5 cM, with the number of loci per LG varying from 2 to 14. Seventeen additional SSR loci were unlinked at a log of odds value of 3.0. Based on chlorophyll loss occurring after greenbug feeding, visual damage ratings, and soil plant analysis development (SPAD), chlorophyll-loss indices were recorded for each RIL and for the parents used in the cross. Composite-interval mapping identified three quantitative trait loci (QTLs) associated with biotype I and five QTLs associated with biotype K. The amount of phenotypic variation explained by these QTLs ranged from 9 to 19.6%. The identification of QTLs that influence greenbug tolerance will not only facilitate the use of marker-assisted selection in sorghum breeding programs but also will provide a solid foundation for detailed characterization of individual loci implicated in greenbug tolerance in sorghum.
Nagaraj
Nandi
N
Department of Entomology, Kansas State University, Manhattan, KS 66506, USA. nnagaraj@dow.com
Reese
John C
JC
Tuinstra
Mitchell R
MR
Smith
C Michael
CM
Amand
Paul St
PS
Kirkham
M B
MB
Kofoid
Kenneth D
KD
Campbell
Leslie R
LR
Wilde
Gerald E
GE
D000818:Animals; D001042:Aphids; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D008040:Genetic Linkage; D005838:Genotype; D010572:Pest Control, Biological; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics; D045868:Sorghum / Q000235:genetics*