Molecular Diagnostic of Both Brown and Orange Sugarcane Rust and Evaluation of Sugarcane Brown Rust Resistance in Tucuman, Argentina, Using Molecular Markers Associated with Bru1 a Broad-Range Resistance Allele

RACEDO J; PERERA M.F; BERTANI R; FUNES C; GONZÁLEZ V; CUENYA M. I; D´HONT A; WELIN B; CASTAGNARO, A. P.

Sugar Tech

Springer

Año: 2016

Brown rust (Puccinia melanocephala) and orange rust (P. kuehnii) cause important yield loss in globalsugarcane production. Due to the difficulties of distinguishing between the two diseases to the naked eye, itis essential to use molecular techniques for an accurate rust diagnosis. A major gene, Bru1, which confersresistance to a broad spectrum of P. melanocephala strains in different parts of the world, has beendescribed, and molecular markers closely associated with this allele have been developed. The aims of thepresent study were: (1) to optimise a PCR-based method to diagnose and characterise the causal agent ofboth rusts in Tucumán; (2) to determine the usefulness of the Bru1 gene in the Sugarcane BreedingProgram of ?Estación Experimental Agroindustrial Obispo Colombres? (EEAOC) by studying itsassociation with resistant and susceptible phenotypes; and (3) to assess the frequency of the Bru1 allele inthe sugarcane germplasm of the EEAOC. Conditions for both rust diagnoses were optimised. Out of 129genotypes evaluated to study the usefulness of the Bru1 allele, 49 were found to be resistant to brown rust,but only eight of these resistant genotypes were positive for the Bru1 allele. Also frequency of appearanceof the Bru1 allele was analysed in 191 sugarcane accessions of the EEAOC germplasm, and its presencewas detected in only 7 % of the genotypes evaluated. In conclusion, although results show that Bru1markers enable positive selection of this character, additional source(s) of resistance are available in theEEAOC Sugarcane Breeding Program.