Distribution and frequency of <i>Bru</i>1, a major brown rust resistance gene, in the sugarcane world collection

Abstract

Abstract Brown rust, caused by Puccinia melanocephala , is an important disease of sugarcane worldwide. Molecular markers for a major brown rust resistance gene, Bru 1, 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. Bru 1 was found across all species within the Saccharum complex, but the frequency varied among species. Bru 1 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 . Bru 1 frequency was highest in the two secondary cultivated species, S. barberi (79.3%) and S. sinense (71.8%). The frequency of Bru 1 was 26.4% and 21.0% in S. officinarum and interspecific hybrid clones, respectively. Knowledge of the distribution and frequency of Bru 1 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.