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Title: Identification and confirmation of greenbug resistance loci in an advanced mapping population of sorghum

item PUNNURI, SOMASHEKKAR - Oklahoma State University
item Huang, Yinghua

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2017
Publication Date: 12/1/2017
Citation: Punnuri, S., Huang, Y. 2017. Identification and confirmation of greenbug resistance loci in an advanced mapping population of sorghum. Journal of Agricultural Science. 155(10):1610-1622.

Interpretive Summary: Sorghum is one of the most important cereal crops, but its production is often limited by greenbug (Schizaphis graminum) when it outbreaks. Our earlier efforts on QTL mapping for greenbug resistance in an F2 mapping population showed promising results with the identification of greenbug resistance QTLs on sorghum chromosome SBI09. In the current study, our objective was to confirm the QTL positions of previously identified in the F2 population using an intercross population and additional SSR markers. The results obtained from this study identified a consistent region of the sorghum chromosome that confers the resistance to greenbug in sorghum; thus confirmed the previously identified greenbug resistance QTLs with increased accuracy of the chromosome location. Furthermore, these efforts have led to locate potential insect resistant candidate genes residing in the QTL region. Thus, the precise location of the QTLs will be useful in cloning and characterization of the greenbug resistance genes in sorghum.

Technical Abstract: Greenbug infestations to sorghum can cause severe and above economic threshold damage in the Great Plains of the United States. This study was to identify quantitative trait loci (QTL) and potential candidate genes residing within the QTL region responsible for greenbug resistance in an advanced mapping population. Greenbug resistance QTLs were mapped onto sorghum chromosome 9 using an intercross population derived from two parents, BTx623 (greenbug-susceptible line) and PI 607900 (greenbug-resistant line). Molecular markers for 115 loci were used to construct a linkage map, which eventually facilitated tagging portions of the sorghum genome regions responsible for greenbug resistance. The molecular genetic map covered all the chromosomes of sorghum with total genome length of 963.0 cM. The advanced mapping population revealed and confirmed the location of greenbug resistance loci identified in our previous study on QTL analysis using an F2 mapping population. These linked markers explained a high phenotypic variation from 72.9% to 80.9% of greenbug resistance in sorghum. The loci for greenbug resistance were mapped to the region flanked by markers Starssbnm 93 and Starssbnm 102 on chromosome 9 with increased allelic effect from the resistant parent. The results from the present study were in concurrence with our early findings in the F2 QTL analysis and identified QTLs had a better confidence interval. This study also indicates that the intercrossed population is useful in detecting QTLs tightly linked to genetic markers with a high resolving power. These markers/QTLs identified from this study can be effectively utilized in marker-assisted selection and map-based cloning experiments.