Phenotypic and molecular characterization of the brazilian panel of sugarcane genotypes

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.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A cana-de-açúcar é uma fonte renovável de energia que possui potencial para expansão. A importância econômica da cana-de-açúcar é devido a sua utilização como matéria-prima, principalmente, para produção de açúcar e etanol e, mais recentemente, geração de energia elétrica a partir dos resíduos lignocelulósicos. O melhoramento genético da cana-de-açúcar é responsável por liberar variedades mais produtivas e resistentes as doenças, mas, no entanto, é um processo longo e de elevado custo. Além disso, a Cana-de-açúcar é poliplóide e com frequente aneuploidia, o que torna o trabalho dos programas de melhoramento ainda mais oneroso. Desta forma, o conhecimento fenotípico e molecular dos acessos que são utilizados em cruzamentos para obtenção de populações segregantes ou que fazem parte de bancos de germoplasma dos programas de melhoramento é de extrema importância, visto que este conhecimento pode direcionar o processo de melhoramento e aumentar as chances de seleção de variedades superiores que atendam a demanda do setor sucroenergético. Assim, neste trabalho, um conjunto de 242 genótipos de cana-de-açúcar, os quais compõem o Painel Brasileiro de Genótipos de Cana-de-açúcar (PBGCA), foi plantado no Centro de Ciências Agrárias da Universidade Federal de São Carlos, em Araras-SP, em delineamento experimental em blocos casualizados com quatro repetições. Foram avaliadas oito caracteristicas fenotipicas de importância econômica: altura de colmos (m), diâmetro de colmos (mm), número de colmos, peso total de parcela (kg), sólidos solúveis (°Brix), teor de sacarose do caldo (Pol%Caldo), teor de sacarose da cana (Pol%Cana) e teor de fibra (%); além disso avaliou-se a incidência de ferrugem marrom (Puccinia melanocephala) a campo e a presença do gene de resistência a esta doença (Bru1). A estimativa de variâncias, a análise de correlação genotípica e a análise de componentes principais evidenciaram a diversidade genética do PBGCA, o qual possui, por exemplo, genótipos contrastantes para teor de açúcar e teor de fibra. Em adição, do total de acessos fenotipicamente resistentes à ferrugem marrom, 72,30% apresentaram o gene Bru1, o qual é fortemente associado com a resistência a esta doença. A caracterização fenotípica e molecular do PBGCA mostrou ser importante para guiar eficientemente as estratégias de melhoramento genético, possibilitando, ainda, estudos futuros de associação entre as características de importância econômica e marcadores moleculares com a finalidade de realizar seleção assistida em cana-de-açúcar

RB975952 – Early maturing sugarcane cultivar

RB975952 is an early maturing sugarcane cultivar released for the South-Central region of Brazil. It should be harvested between April and May, and it is recommended for planting in environments with medium to high production potential. RB975952 has high resistance levels to the main diseases of the crop, it also has a good shoot development after mechanical harvesting, and high sucrose yields

RB975242 and RB975201 - Late maturation sugarcane varieties

The sugarcane varieties RB975201 and RB975242 were developed and released for harvest at the end of the season (late maturation) in the CentralSouth region of Brazil. In specific environments, these varieties were compared with commercial standards in sugar yield per area. They are resistant to major sugarcane diseases and present the Bru1 gene of resistance to brown rust

Differential expression in leaves of Saccharum genotypes contrasting in biomass production provides evidence of genes involved in carbon partitioning

The development of biomass crops aims to meet industrial yield demands, in order to optimize profitability and sustainability. Achieving these goals in an energy crop like sugarcane relies on breeding for sucrose accumulation, fiber content and stalk number. To expand the understanding of the biological pathways related to these traits, we evaluated gene expression of two groups of genotypes contrasting in biomass composition.First visible dewlap leaves were collected from 12 genotypes, six per group, to perform RNA-Seq. We found a high number of differentially expressed genes, showing how hybridization in a complex polyploid system caused extensive modifications in genome functioning. We found evidence that differences in transposition and defense related genes may arise due to the complex nature of the polyploid Saccharum genomes. Genotypes within both biomass groups showed substantial variability in genes involved in photosynthesis. However, most genes coding for photosystem components or those coding for phosphoenolpyruvate carboxylases (PEPCs) were upregulated in the high biomass group. Sucrose synthase (SuSy) coding genes were upregulated in the low biomass group, showing that this enzyme class can be involved with sucrose synthesis in leaves, similarly to sucrose phosphate synthase (SPS) and sucrose phosphate phosphatase (SPP). Genes in pathways related to biosynthesis of cell wall components and expansins coding genes showed low average expression levels and were mostly upregulated in the high biomass group.Together, these results show differences in carbohydrate synthesis and carbon partitioning in the source tissue of distinct phenotypic groups. Our data from sugarcane leaves revealed how hybridization in a complex polyploid system resulted in noticeably different transcriptomic profiles between contrasting genotypes

CULTIVAR RELEASE - RB965902 and RB965917 – Early/medium maturing sugarcane varieties

The varieties RB965902 and RB965917 were developed for harvesting at the beginning to the middle of the sucroseextraction period (early/medium maturity) and released for the South-Central region of Brazil. In specific environments, the tons ofPol per area (sucrose yield) of these varieties is higher than of the commercial standard RB855453 and they are resistant to the maindiseases of the crop