Distribution and frequency of Bru1, a major brown rust resistance gene, in the sugarcane world collection

Authors: PARCO, ARNOLD - LSU Agcenter; Hale, Anna; AVELLANEDA, MAVIR - LSU Agcenter; HOY, JEFFREY - LSU Agcenter; KIMBENG, COLLINS - LSU Agcenter; PONTIFF, MICHAEL - LSU Agcenter; McCord, Per; Ayala-Silva, Tomas; Todd, James; BAISAKH, NIRANJAN - LSU Agcenter

Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2017
Publication Date: 7/16/2017
Citation: Parco, A.S., Hale, A.L., Avellaneda, M.C., Hoy, J.W., Kimbeng, C.S., Pontiff, M.J., Mccord, P.H., Ayala Silva, T., Todd, J.R., Baisakh, N. 2017. Distribution and frequency of Bru1, a major brown rust resistance gene, in the sugarcane world collection. Plant Breeding. 136:637-651. https://doi.org/10.1111/pbr.12508.
DOI: https://doi.org/10.1111/pbr.12508

Interpretive Summary: Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane worldwide. Many sugarcane plants contain a gene, Bru1, that confers resistance to brown rust. Plants containing this gene are generally resistant to the disease. Sugarcane is a genetically complex crop that is derived from multiple species (Saccharum barberi, S. sinese, S. spontaneum, S. robustum, and S. officinarum) as well as some other related genera. Two DNA markers associated with the Bru1 gene, were used to screen a total of 1,282 clones in the World Collection of Sugarcane and Related Grasses (WCSRG) to determine the distribution and frequency of the gene in sugarcane, and its relatives. Bru1 was found across all species within the Saccharum complex, but the frequency varied among individual species in the group. Among the wild relatives of sugarcane, Bru1 was more prevalent in S. robustum clones (59.1%), whereas it occurred in low frequency and exhibited the highest level of genetic variability (18.8%) in clones of S. spontaneum. Among the domesticated and cultivated relatives of sugarcane, Bru1 frequency was highest in the two secondary cultivated species, S. barberi (79.3%) and S. sinense (71.8%). The frequency of Bru1 was 26.4% and 21.0% in S. officinarum and interspecific hybrid clones, respectively. Knowledge of the distribution and frequency of Bru1 in the WCSRG will help breeders to determine where diversity exists in the Saccharum complex and will help with the development of future DNA markers that could be used to hasten variety development.

Technical Abstract: Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane worldwide. Molecular markers for a major brown rust resistance gene, Bru1, were used to screen a total of 1,282 clones in the World Collection of Sugarcane and Related Grasses (WCSRG) to determine the distribution and frequency of the gene in Saccharum species and related genera. Bru1 was found across all species within the Saccharum complex, but the frequency varied among species. Bru1 was more prevalent in S. robustum clones (59.1%), whereas it occurred in low frequency and exhibited the highest level of variability as determined by the presence of one or both markers (18.8%) in clones of S. spontaneum. Bru1 frequency was highest in the two secondary cultivated species, S. barberi (79.3%) and S. sinense (71.8%). The frequency of Bru1 was 26.4% and 21.0% in S. officinarum and interspecific hybrid clones, respectively. Knowledge of the distribution and frequency of Bru1 in the WCSRG will complement efforts to characterize diversity in the Saccharum complex for the expected expanded use of marker-assisted selection in the future.