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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Peanut and Small Grains Research Unit » Research » Publications at this Location » Publication #418961
Research Project: Genetic Improvement for Resistance to Aphids and Major Diseases in Wheat, Barley, and Sorghum in the Great Plains

Location: Peanut and Small Grains Research Unit

Title: SgR1, encoding a leucine-rich repeat containing receptor-like protein, is a major aphid (Schizaphis graminum) resistance gene in sorghum

Author
item HENGYOU, ZHANG - Oklahoma State University
item LIULING, YAN - Oklahoma State University
item Huang, Yinghua

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2024
Publication Date: 12/24/2024
Citation: Hengyou, Z., Liuling, Y., Huang, Y. 2024. SgR1, encoding a leucine-rich repeat containing receptor-like protein, is a major aphid (Schizaphis graminum) resistance gene in sorghum. International Journal of Molecular Sciences. 26(1). Article 19. https://doi.org/10.3390/ijms26010019.
DOI: https://doi.org/10.3390/ijms26010019

Interpretive Summary: The greenbug aphid (Schizaphis graminum) is one of the most destructive insect pests, which feeds on the plants of Gramineae family members such as wheat, barley and sorghum, resulting in significant damage to the host plants and yield loss. Plant resistance to greenbug has been identified in those crop species. Aphid resistance quantitative trait loci (QTLs) have also been reported in several resistant genetic sources of sorghum. Furthermore, the results of our recent studies revealed that the sorghum variety PI 607900 carries several QTLs associated with the resistance to greenbug. But there is an urgent need for isolation of the resistance genes to facilitate molecular breeding for a better management of this pest. More recently we identified a major QTL (gene) on chromosome 9, (Schizaphis graminum resistance gene, (SgR1), in this resistant line, conferring genetic resistance to greenbug biotype I (GBI) using the high-resolution molecular mapping approach. Then we successfully isolated the gene SgR1 using the map-based cloning method, and subsequently its biological function was validated by successfully expressing this gene in Arabidopsis, where the SgR1 is inducible in Arabidopsis by green peach aphids. Those results indicate that sorghum resistance to GBI is simply inherited by the SgR1, rather than multi-genic complex traits, thus, making it much easier and faster to be introduced into sorghum elite cultivars with molecular breeding. Our findings offer an efficient tool to facilitate the breeding of GBI-resistant sorghum varieties.

Technical Abstract: The Greenbug, Schizaphis graminum (Rondani) is one of the important cereal aphid pests of sorghum in the Great Plains of the United States as well as many other parts of the world. The Sorghum bicolor variety PI 607900 carries a gene SgR1 underlying plant resistance to greenbug biotype I (GBI) and is also determined as the major gene conferring the greenbug resistance based on the strong association of its presence with the resistance phenotype in sorghum plants. In the study, we have successfully isolated the SgR1 gene using the map-based cloning approach, and subsequent molecular characterization of the is gene revealed that SgR1 gene encodes a leucine-rich repeat containing receptor-like protein (LRR-RLP). The DNA sequences of the SgR1 genes are conserved among those GBI-resistance sorghum accessions but are variable within susceptible panels. Furthermore, an indel (-965 nt) at its promoter region and a single-nucleotide polymorphism (SNP, 592 nt) in the CDS of SgR1 are well conserved within resistant lines. When the SgR1 gene was transferred into Arabidopsis, the SgR1 was activated in the transgenic Arabidopsis plants in response to attack by green peach aphids (Myzus persicae Sülzer) according to the results of histochemical assay, and GUS-activity was detected in situ spots around the vasculature of the leaf where phloem located. Overall, this study confirms that SgR1 gene coding for an LRR-RLP protein is the major gene greenbug resistance gene in sorghum, which is the first greenbug resistance gene cloned so far and indicates that the simple-inherited GBI resistance gene can be used for genetic improvement of sorghum crops with genetic resistance to GBI via molecular breeding or cross-based conventional breeding technologies.