40 research outputs found
Phenotypic and molecular characterization of the brazilian panel of sugarcane genotypes
No full textSugarcane 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
Marcadores moleculares funcionais associados com resistência a murcha de fusário em feijoeiro comum.
No full textEste trabalho objetivou selecionar marcadores microssatélites polimórficos em populações segregantes derivadas dos cruzamentos entre cultivares resistentes (Milionário 1732 ou FT Tarumã) e susceptível (Macanudo) à murcha do fusário
Mapeamento genético da resistência a murcha do fusario em feijoeiro comum.
No full textEste trabalho objetivou identificar marcadores microssatélites ligados a genes de resistência a Fusarium oxysporum f. sp. phaseoli em feijoeiro comum
A genome-wide association study identified loci for yield component traits in sugarcane (Saccharum spp.).
No full textSugarcane (Saccharum spp.) has a complex genome with variable ploidy and frequent aneuploidy, which hampers the understanding of phenotype and genotype relations. Despite this complexity, genome-wide association studies (GWAS) may be used to identify favorable alleles for target traits in core collections and then assist breeders in better managing crosses and selecting superior genotypes in breeding populations. Therefore, in the present study, we used a diversity panel of sugarcane, called the Brazilian Panel of Sugarcane Genotypes (BPSG), with the following objectives: (i) estimate, through a mixed model, the adjusted means and genetic parameters of the five yield traits evaluated over two harvest years; (ii) detect population structure, linkage disequilibrium (LD) and genetic diversity using simple sequence repeat (SSR) markers; (iii) perform GWAS analysis to identify marker-trait associations (MTAs); and iv) annotate the sequences giving rise to SSR markers that had fragments associated with target traits to search for putative candidate genes. The phenotypic data analysis showed that the broad-sense heritability values were above 0.48 and 0.49 for the first and second harvests, respectively. The set of 100 SSR markers produced 1,483 fragments, of which 99.5% were polymorphic. These SSR fragments were useful to estimate the most likely number of subpopulations, found to be four, and the LD in BPSG, which was stronger in the first 15 cM and present to a large extension (65 cM). Genetic diversity analysis showed that, in general, the clustering of accessions within the subpopulations was in accordance with the pedigree information. GWAS performed through a multilocus mixed model revealed 23 MTAs, six, three, seven, four and three for soluble solid content, stalk height, stalk number, stalk weight and cane yield traits, respectively. These MTAs may be validated in other populations to support sugarcane breeding programs with introgression of favorable alleles and marker-assisted selectio
Validação de marcadores moleculares associados à resistência à ferrugem marrom em cana-de-açúcar
No full textRESUMO A ferrugem marrom causada pelo fungo Puccinia melanocephala é uma importante doença em cana-de-açúcar (Saccharum spp.) e está presente em praticamente todas as áreas de cultivo. Um gene de efeito maior, Bru1, foi descrito como fonte de resistência durável da cana-de-açúcar contra isolados de P. melanocephala. O objetivo deste estudo foi avaliar a eficiência de dois marcadores moleculares fortemente associados ao gene Bru1, R12H16 e 9O20-F4-RsaI, para predição da resistência genética à ferrugem marrom em variedades de cana-de-açúcar. Para tanto, foram utilizadas neste estudo 14 variedades RB, desenvolvidas pela RIDESA (Rede Interuniversitária para o Desenvolvimento do Setor Sucroenergético), as quais estão entre as 10 mais cultivadas na região Centro-Sul do Brasil no período de 1974 a 2015. Para avaliação da doença a campo foi conduzido um experimento em blocos casualizados com quatro repetições. A severidade da ferrugem marrom foi quantificada de acordo com escala diagramática que varia de 1 (mais resistente) a 9 (mais suscetível) e os dados obtidos foram analisados através de modelo misto linear generalizado (GLMM). Concomitantemente, foi extraído o DNA total das 14 variedades e, em seguida, foi realizada amplificação dos marcadores moleculares, que foram classificados em haplótipos. Do total de variedades, 12 não mostraram sintomas da doença e, através da análise via GLMM, apresentaram probabilidade de 99,35% de serem resistentes; destas, 91,66% foram haplótipo 1, ou seja, tiveram a presença de ambos os marcadores associados ao gene Bru1. Portanto, pode-se concluir que os marcadores moleculares R12H16 e 9O20-F4-RsaI foram altamente eficientes em predizer fenótipos resistentes e que provavelmente o gene Bru1 seja a principal fonte de resistência de cana-de-açúcar à ferrugem marrom nos campos comerciais do Brasil.</jats:p
Molecular evaluation and phenotypic screening of brown and orange rust in Saccharum germplasm
No full textMolecular evaluation and phenotypic screening of brown and orange rust in Saccharum germplasm.
No full textBrazil is the largest global producer of sugarcane and plays a significant role-supplier of sugar and bioethanol. However, diseases such as brown and orange rust cause substantial yield reductions and economic losses, due decrease photosynthesis and biomass in susceptible cultivars. Molecular markers associated with resistance genes, such as Bru1 (brown rust) and G1 (orange rust), could aid in predicting resistant genotypes. In this study, we sought to associate the phenotypic response of 300 sugarcane accessions with the genotypic response of Bru1 and G1 markers. The field trials were conducted in a randomized block design, and five six-month-old plants per plot were evaluated under natural disease conditions. Genotypic information about the presence or absence of Bru1 (haplotype 1) and G1 gene was obtained after extraction of genomic DNA and conventional PCR. Of the total accessions evaluated, 60.3% (181) showed resistance to brown rust in the field, and of these, 70.7% (128) had the Bru1 gene present. Considering the field-resistant accessions obtained from Brazilian breeding programs (116), the Bru1 was present in 77,6% of these accessions. While alternative resistance sources may exist, Bru1 likely confers enduring genetic resistance in current Brazilian cultivars. Regarding the phenotypic reaction to orange rust, the majority of accessions, 96.3% (288), were field resistant, and of these, 52.7% (152) carried the G1 marker. Although less efficient for predicting resistance when compared to Bru1, the G1 marker could be part of a quantitative approach when new orange rust resistance genes are described. Therefore, these findings showed the importance of Bru1 molecular markers for the early selection of resistant genotypes to brown rust by genetic breeding programs
RB965902 and RB965917 – Early/medium maturing sugarcane varieties
No full textThe varieties RB965902 and RB965917 were developed for harvesting at the beginning to the middle of the sucrose extraction period (early/medium maturity) and released for the South-Central region of Brazil. In specific environments, the tons of Pol per area (sucrose yield) of these varieties is higher than of the commercial standard RB855453 and they are resistant to the main diseases of the crop
Differential expression in leaves of Saccharum genotypes contrasting in biomass production provides evidence of genes involved in carbon partitioning
No full textThe 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
RB965902 and RB965917 Early/medium maturing sugarcane varieties
No full textThe varieties RB965902 and RB965917 were developed for harvesting at the beginning to the middle of the sucrose extraction period (early/medium maturity) and released for the South-Central region of Brazil. In specific environments, the tons of Pol per area (sucrose yield) of these varieties is higher than of the commercial standard RB855453 and they are resistant to the main diseases of the crop.</jats:p
