Mapeamento de QTL para resistência a Sporisorium scitamineum em população bi-parental de cana-de-açúcar
Resumen
The sugarcane is a major global economic importance culture, especially for Brazil.
The country is the largest producer of culture and its by-products, sugar and alcohol.
The sugarcane has received attention for the generation of electricity. Since the
importance of the sugar-energy sector, there is a need to increase agricultural
production. This culture is exposed to various diseases caused by pathogens that
impair the production of culture. Coal disease is one of them, caused by the fungus
S. Scitamineum, making it less susceptible productive varieties and can cause loss of
up to 100% of the plantation. More productive varieties with resistance to more
diseases, obtained in less time are focused on breeding programs. The study aims to
find microsatellite markers (SSR) associated with resistance of sugarcane to the
fungus S. scitamineum. It used an F1 population (SP81-3250 RB925345 x)
composed of 238 genotypes. Artificial inoculation of sugarcane stalks of the
population through telia injection was made. The billets were kept in a greenhouse,
and 25 were carried out between January and September 2014 for the first
experiment and August 2015 to February 2016 for the experiment II, to identify the
incidence of the disease. Molecular analysis and construction of linkage map were
made by genotyping with SSR markers, which enabled the construction of linkage
map with 128 brands linked, generating 49 linkage groups with a total length of
1297.68 cm. For data on the incidence of coal was used to calculate the area under
the disease progress curve (AACPD), normalized to BLUPS values. The analysis
allowed us to observe a population with more tolerant genotypes in experiment I and
little disease in experiment II. In addition, it was noted that for the first experiment,
the 10th to the 25th evaluation, the results were highly correlated, it was not repeated
for the second trial. Experiment II showed low incidence in all genotypes of the
population and patterns in the study. This incidence difference between the two
experiments probably occurred by the difference in temperature conditions to which
they were exposed, and the first experiment was set up in the summer with a starting
temperature higher and the second trial began with mild temperatures and were
increasing with time, the same occurs for the incidence of the disease. The
association between phenotype and genotype was performed by analysis of
variance, converted to LOD score. It was possible to verify an EST-SSR marker, SCB
370, which was significant (LOD> 3), explaining in 5% of the phenotypic variation for
the experiment I.