Validation of the effectiveness of an emaculation treatment in sugarcane by using molecular markers

PERERA, M. F.; GARCÍA, M. B.; DÍAZ ROMERO, C.; CUENYA, M. I.; FILIPPONE, M. P. Y CASTAGNARO, A. P.

XXVIII ISSCT Proceedings

ISSCT

Año: 2012;

Parents used in sugarcane crosses are classified as male or female based on the relative amounts of viable pollen produced. High pollen production determined by both genotype and environmental conditions reduces ¡°female inflorescence¡± availability and restricts the possibility of cross combinations. However, male parents could be employed as female parents when an efficient emasculation treatment, which implies pollen sterilization, is used. On the other hand, an ideal approach for hybridity testing is the use of molecular markers. To determine the effectiveness of an emasculation treatment (immersion of the panicle in water at 50¨¬C for 5 minutes), six cross combinations between two varieties commonly used as males, LCP85-384 and RA87-3, were evaluated by using simple sequence repeats markers (SSRs). After emasculation treatment, pollen absence was confirmed, whereas pollen was detected in both varieties without treatment. Sexual crosses were performed successfully and no viable seeds were obtained when LCP85-384 and RA87-3 were emasculated and selfed, respectively. Fifteen SSR primer pairs were evaluated in order to choose one combination that produced an appropriate molecular profile. DNA of progeny from each cross-combination was screened using primers showing marker polymorphism between parents and presence or absence of polymorphic markers was scored. Selected primers produced seven polymorphic and three monomorphic bands between the progenitors. Segregation analysis showed that each marker segregated in a Mendelian fashion (¥ö2 tests, P¡Â0.05) for each cross combination. Our results indicate that emasculation treatment was successful for both varieties and did not cause serious reduction in stigma and ovary viability. This method is simpler, faster and cheaper than other emasculation techniques and it will allow the expansion of bi-parental crosses. In addition, using the SSR technique allowed us to assess the fidelity of sugarcane crosses. Thus, both implemented tools will improve crossing efficiency of sugarcane breeding programs.