Alternative sources of resistance to sugarcane brown rust disease

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

EUPHYTICA

SPRINGER

Lugar: Berlin; Año: 2013 p. 429 - 436

0014-2336

Brown rust, caused by the fungus Pucciniamelanocephala, is responsible for important yieldlosses in sugarcane production globally and it istherefore an important objective to introduce resistanceto this disease in breeding programs. A majorgene, Bru1, has been shown to confer resistance toP. melanocephala strains from different parts of theworld and two molecular markers, R12H16 and 9O20-F4, closely associated to this gene have been previouslyreported. The usefulness of these moleculardiagnostic markers in order to predict a rust resistantphenotype under natural high pressure inoculumsconditions was analyzed. A total of 129 sugarcaneaccessions were evaluated under field infection forresistance or susceptibility to brown rust and subsequentlyscreened for presence or absence of the two Bru1 diagnostic markers. A total of 49 genotypes(38 %) were phenotyped as resistant to brown rust butonly eight (16.3 %) of them were harboring the Bru1gene. To determine overall frequency of the Bru1 inthe local sugarcane germplasm collection, 190 additionalgenotypes were examined. Presence of Bru1, asdetermined by the diagnostic markers, was detected inonly 7 % of the genotypes evaluated. In conclusion,Bru1 diagnostic markers enable positive selection forbrown rust resistance in sugarcane and moreoverallowed detecting at least one additional source(s) ofresistance. Interestingly, whilst only little geneticvariability of rust resistance independent of Bru1 hasbeen reported previously, this alternative geneticresource(s) found in our local germplasm constitutesthe predominant one and should be helpful in order toamplify the narrow genetic basis for brown rustresistance in sugarcane.