Caracterização fenotípica e molecular do painel brasileiro de genótipos de cana-de-açúcar
Resumo
Sugarcane is a renewable source of energy and has potential for expansion. The
economic importance of sugarcane is due to its use as raw material, mainly for the
sugar and ethanol production and, more recently for the electricity generation from
lignocellulosic residues. The genetic improvement of sugarcane is responsible for
releasing more productive and resistant cultivars but, however, is a long process with
high cost. Furthermore, the sugarcane is polyploid and often presents aneuploid,
which makes the work of breeding programs even more hampered. Thus, the
phenotypic and molecular knowledge of the access that are commonly used for the
crosses to obtain segregating populations or that are part of genebanks of breeding
programs is of extreme importance, because this knowledge may drive the
improvement process and increases the chances of selecting superior cultivars that
meet the demand of the sugarcane industry. In this work, a panel of 242 genotypes
of sugarcane, which compose the Brazilian Panel of Sugarcane Genotypes
(PBGCA), was planted in the Agricultural Sciences Center of the Federal University
of São Carlos, at Araras-SP, in a completely randomized block design with four
replications. We evakuated eight phenotypic traits of economic importance: stalk
height (m), stalk diameter (mm), stalk number, total weight (kg), soluble solids
content (ºBrix), juice sucrose content (POL%Caldo), cane sucrose content
(POL%Cana) and fiber content (FIB%); and also the incidence of brown rust
(Puccínia melanocephala) at field and the presence of the resistance gene of this
disease (Bru1). The estimate of variance, genotypic correlation analysis and principal
component analysis showed the genetic diversity of PBGCA, which has, for example,
contrasting genotypes for sucrose content and fiber content. In addition, from all
resistant accessions on the field to brown rust, 72.30% present the Bru1 gene, which
is strongly associated with resistance. Phenotypic and molecular characterization of
PBGCA showed to be an efficiently important guide for the breeding strategies and
enables future studies of association between traits of economic importance and
molecular markers in order to perform assisted selection in sugarcane.