Snap bean breeding for rust resistance: validation of molecular markers for the ur-11 gene introgression

Authors: KUMARI, H.M.P.S. - Department Of Agriculture Government Of Sri Lanka; WEEBADDE, C. K. - Michigan State University; BANDARANAYAKE3, P.C.G. - University Of Peradeniya; Pastor Corrales, Marcial; RAJAPAKSHE, R.G.A.S. - Department Of Agriculture Government Of Sri Lanka

Submitted to: Journal of Semi-Arid Tropical Agricultural Research (Journal of SAT Research)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2021
Publication Date: 1/1/2022
Citation: Kumari, H., Weebadde, C., Bandaranayake3, P., Pastor Corrales, M.A., Rajapakshe, R. 2022. Snap bean breeding for rust resistance: validation of molecular markers for the ur-11 gene introgression. Journal of Semi-Arid Tropical Agricultural Research (Journal of SAT Research). 33(1):57-66. http://doi.org/10.4038/tar.v33i1.8535.
DOI: https://doi.org/10.4038/tar.v33i1.8535

Interpretive Summary: Bean rust caused by the fungus Uromyces appendiculatus, is one of the most destructive bean diseases in temperate, tropical, and sub-tropical regions. In Sri Lanka, bean rust is a destructive pathogen affecting the quality and quantity of common bean yield. Host resistance is the most cost-effective strategy to control the bean rust disease; but developing rust-resistant varieties is complicated by the very large number of different virulent strains (races) that comprise the populations of the bean rust pathogen. The present study aimed to initiate a program to develop rust-resistant snap beans in Sri Lanka. To that end, a popular snap bean from Sri Lanka was crossed with a common bean accession, known as PI 18996, obtained from the USDA-ARS Bean research project in Beltsville, Maryland. PI 181996 has the Ur-11 rust resistance gene that confers the broadest rust resistance in the world. The progeny, populations of plants obtained from the crosses between the snap bean variety from Sri Lanka with PI 181996, were inoculated with four rust races present in Sri Lanka. These progeny were also scored for presence of genetic markers associated with the Ur-11 rust resistance gene. Our results indicated that Ur-11 conferred resistance to all of the Sri Lanka rust strains that we tested, thus facilitating breeding of local rust resistant varieties. The results benefit producers and consumers of snap bean in Sri Lanka.

Technical Abstract: Bean rust caused by Uromyces appendiculatus fungus is one of the most destructive diseases reported in temperate, tropical, and sub-tropical regions, affecting the quality and quantity of common bean (Phaseolus vulgaris L) yield. The present study aimed to improve the breeding process of snap beans for rust resistance by identification of inheritance patterns of resistant genes using phenotypic and molecular markers. Among the different genes identified, Ur-11 has wide-spectrum resistance to 89 out of 90 reported races of the rust pathogen. Therefore, the common bean cultivar PI 181996, having the Ur-11 gene, was used as the rust resistance donor parent while the local popular snap bean variety Kappetipola nil, susceptible to all locally reported races of the rust pathogen in Sri Lanka, was selected as the susceptible (Recurrent) parent. The introgression of the Ur-11 gene from the cultivar PI 181996 in F1, F2, and BC1F1 populations were phenotypically evaluated using standard screening method while validating random amplified polymorphic DNA (RAPD) marker, OPAC 20 and sequence characterized amplified region (SCAR) marker, SAE 19 and GT 2. Coupling markers (OPAC 20 and GT-2) and repulsion marker (SAE 19) showed 95% and 100% of expected results for henotypically resistant and susceptible lines respectively. The results showed that the Ur-11 gene in PI 181996 can be tagged with SCAR marker GT-2 and SAE 19 and can be used for marker assisted selection to identify the presence of the Ur-11 gene in the snap bean rust-resistance breeding program. Introgression of the Ur-11 gene helped to develop genetic resistance to local races of the rust pathogen, and the selected progenies could be developed as new resistant snap bean breeding lines.