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Research Project: Areawide Pest Management of the Invasive Sugarcane Aphid in Grain Sorghum – Genetic Analysis of New SCA Resistant Lines

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Title: Rsg1.a3: A new allele conferring unique resistance to greenbug biotype H at the Rsg1 locus in Hordeum vulgar ssp spontaneum

Author
item Xu, Xiangyang
item Mornhinweg, Dolores - Do
item Bai, Guihua
item STEFFENSON, BRIAN - University Of Minnesota
item BIAN, RUOLIN - Kansas State University
item Li, Genqiao
item Bernardo, Amy

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2021
Publication Date: 8/4/2021
Citation: Xu, X., Mornhinweg, D.W., Bai, G., Steffenson, B., Bian, R., Li, G., Bernardo, A. 2021. Rsg1.a3: A new allele conferring unique resistance to greenbug biotype H at the Rsg1 locus in Hordeum vulgar ssp spontaneum. Crop Science. 61:3578-3585. https://doi.org/10.1002/csc2.20581.
DOI: https://doi.org/10.1002/csc2.20581

Interpretive Summary: Greenbug not only causes cereal yield losses worldwide, but also serves as a vector for several destructive viruses. Greenbug biotype H is virulent to all known barley resistance sources, and new barley greenbug resistance genes are urgently needed. Wild barley accession WBDC366 possesses a greenbug resistance gene uniquely effective against greenbug biotype H. Linkage analysis mapped this gene in a 1.14 Mb interval (666,512,150-667,651,446 bp) on the long arm of chromosome 3H based on the Morex reference sequence r1. Greenbug assays and allelism test results suggested that this resistance gene, designated Rsg1.d, is allelic to Rsg1. Two KASP markers (KASP-Rsg336-1 and KASP-Rsg336-2) closely linked to Rsg1.d were developed to facilitate the introgression of Rsg1.d and Rsg1 into locally adapted barley cultivars. Rsg1.d confers resistance to greenbug biotypes C, E, H, I, WY81, WY12 MC, and WY86. Pyramiding Rsg1.d with other three greenbug resistance genes may enhance durability of greenbug-resistant cultivars.

Technical Abstract: Greenbug (Schizaphis graminum Rondani) is one of the aphids causing significant cereal yield losses worldwide, and greenbug biotype H is virulent to all known greenbug resistance genes in barley (Hordeum L.) Wild barley (Hordeum vulgare ssp. spontaneum) accession WBDC336 (PI 682028) exhibits resistance to greenbug biotypes C, E, H, I, WY81, WY12 MC, and WY86. To investigate the genetics of greenbug resistance in WBDC336, a recombinant inbred line (RIL) population was developed from the cross Weskan × WBDC336. The RIL population was evaluated for responses to greenbug Biotype E and genotyped using genotyping-by-sequencing. Among 67,238 single nuceotide polymorphisms (SNPs) identified, 3,907 high quality SNPs were selected for gene mapping after several filtering steps. Linkage analysis positioned the greenbug resistance gene to a 1.14-Mb interval in the terminal region of the long arm of chromosome 3H in WBDC336, where the greenbug resistance gene Rsg1 resides. Greenbug assays and an allelism test indicated that the greenbug resistance gene in WBDC336 is likely an allele at the Rsg1 locus and was given the allele designation Rsg1.a3. Two kompetitive allele-specific polymerase chain reaction (KASP) markers were developed from SNPs closely linked to Rsg1.a3, and these markers can be used to tag both alleles at the Rsg1 locus in breeding program utilizing marker-assisted selection.