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Title: Screening for Resistance to Brown Rust of Sugarcane: Use of Bru1 resistance gene prospects and challenges

item Glynn, Neil
item Comstock, Jack
item McCorkle, Katherine

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/10/2012
Publication Date: 6/21/2012
Citation: Glynn, N.C., Comstock, J.C., Mccorkle, K.M. 2012. Screening for Resistance to Brown Rust of Sugarcane: Use of Bru1 resistance gene prospects and challenges. American Society of Sugar Cane Technologists. 32:82.

Interpretive Summary:

Technical Abstract: Brown rust of sugarcane caused by, Puccinia melanocephala, is a serious problem in the US sugarcane industry. A major resistance gene, Bru1 was identified and methodology for detecting it was developed by French scientists at CIRAD. The majority of the research resulting in the discovery of Bru1 resistance gene was funded by the International Consortium for Sugarcane Biotechnology (ICSB). Our objective was to determine the frequency of Bru1 in parental clones, historical clones and all the clones in Stage II (CP 10 Series) at Canal Point, Florida and to determine its usefulness in the CP Cultivar Development Program. Of the 1072 parental clones used at Canal Point, Bru1 was detected in 27 % (287) of the clones. The frequency of Bru1 differed among the parental clones used for the Florida, Louisiana and Texas crossing programs with 42 % of the Florida clones and 6 % of the Louisiana clones containing the resistance gene. There was an increase in the Bru1 frequency in CP clones through time indicating a selection of the gene based on selection of resistance by lack of rust development in the field. Interestingly brown rust resistant commercial cultivars, CP 80-1743, CP 88-1762, and CP 89-2143 have Bru1 gene while susceptible cultivar CP 96-1252 does not. Thus, over 75 % of the commercial sugarcane acreage in Florida relies on Bru1 to control brown rust. Bru1 was detected in 44 % of the 1515 clones in Stage II. Detection of Bru1 in the CP development program will increase the frequency of brown rust resistance. However, a serious threat is the breakdown of Bru1 resistance as has happened in similar major genes in other crops. Fortunately, there appears to be other resistance genes present in the germplasm since some clones are resistant but Bru1 was not detected.