masterThesis
Associação genômica de marcadores SNPs com a resistência do trigo a germinação pré-colheita
Fecha
2017-02-09Registro en:
MILIOLI, Anderson Simionato. Associação genômica de marcadores SNPs com a resistência do trigo a germinação pré-colheita. 2017. 52 f. Dissertação (Mestrado em Agronomia) - Universidade Tecnológica Federal do Paraná, Pato Branco, 2017.
Autor
Milioli, Anderson Simionato
Resumen
Pre-harvest sprouting (PHS) in wheat, has been responsible for considerable losses in productivity and quality in several growing regions worldwide. Several breeding programs have sought to select genotypes with high levels of resistance, but due to the complexity of the trait, the advances achieved are inexpressive, and most efficient techniques to identify superior genotypes are demanded. Thus, the objective of this study was to perform a genome-wide association analysis, for identify SNPs markers and genomic regions associated with resistance to PHS in wheat, for later use in marker-assisted selection (MAS). For this, 344 wheat genotypes of different times and companies that represents the genetic basis of wheat grown in Brazil were used. The experiment consisted of three main steps: genotyping, phenotyping and genome-wide association analysis. In the genotyping step, the DNA extraction and quantification was conducted, and the samples were genotyped with a DNA chip for detection of SNPs containing 35,000 SNPs for the wheat genome. In the phenotyping step, an experiment was conducted in Cascavel-PR, in a randomized block design with three replicates. The genotypes were evaluated at physiological maturity, with the collection of 20 spikes per genotype, and these were subjected to a simulated rainfall for germination, being then allocated scores according to the germination rate observed. After the genotypic and phenotypic determinations, it was conducted a genome-wide association analysis to identify molecular markers associated with resistance to PHS. Ten significant markers were identified on chromosomes 3B, 4A, 5B, 5D, 6D, 7B and 7D, where QTLs (Quantitative Trait Loci) associated with pre-harvest sprouting resistance are present. The SNPs were localized in genes encoding enzymes involved in the gibberellin and abscisic acid signaling pathways, maltose hydrolysis and cell division and stretching. The explanation of the phenotypic variation by the significant markers ranged from 4.2 to 5.4%, which is expected for quantitative traits. Significant markers identified in the present study, after being validated, could be used in MAS programs for the early selection of genotypes more resistant to PHS in wheat, allowing the obtainment of desirable genotypes in the more agile and precise way.