Behavior of sugarcane Germplasm of the Sugarcane Breeding Program (EEAOC) against Puccinia kuehnii, the causal agent of orange rust, in Misiones, Argentina.

FUNES C; HENRIQUEZ DD; COSTILLA DD; CHAVES S; BERTANI RP; JOYA CM; AYBAR GUCHEA M; GUTIERREZ H; GONZÁLEZ V; CUENYA MI

San Miguel de Tucumán

Congreso; XXX ISSCT Congress; 2019

In April 2015 orange rust was detected for the first time in a commercial sugarcane field in aprovince of northeast of Argentina (Misiones) 1200 km from the main sugarcane area of thiscountry. The objective of this study was to evaluate the behavior of sugarcane germplasm of theSugarcane Breeding Program (SCBP) of the Estación Experimental Agroindustrial ObispoColombres (EEAOC) against Puccinia kuehnii under field conditions. In September 2015, 192sugarcane clones were planted in a field trial in Fachinal, Misiones. This material included theparents, among which are the commercial varieties grown in Tucumán, and other clones of thegermplasm collection of the SCBP. An unknown variety at Misiones, affected with orange rust,was planted around the trial. Orange rust severity was evaluated between 2016 and 2018.Sugarcane leaf samples with rust symptoms were collected and examined in the EEAOClaboratory, and the identity of the causal agent was verified by PCR using specific primers. Whenmicroscopic observations were done, uredinia and urediniospores previously described for P.kuehnii were detected in 23 (11.98%) and 15 (7.81%) genotypes in 2016 and 2017, respectively.P. kuehnii was not detected in 2018. Furthermore, a high percentage of P. kuehnii and P.melanocephala co-infection was observed during 2016 and 2017, resulting in 78.26% and93.33% of the total positive samples for P. kuehnii, respectively. Results revealed the existenceof potential resistant sources against orange rust in the germplasm collection of the SCBP(EEAOC) since 88% of the genotypes were disease-free during the three-year evaluation