Associação de marcadores-QTL com características de tolerância ao déficit hídrico em plântulas de milho

Abstract

Maize is one of the most important crops in Brazil, but its yield potential is severely influenced by the water deficit, due to constant climate changes, mainly in the second harvest, but also not uncommon in the first harvest, with losses to farmers. Selective breeding can offer an opportunity for farmers through identifying maize types that are tolerant to drought in the initial seedling stage. For this purpose, it was necessary to identify regions of the genome that can be used as markers for drought tolerance. Thus, experiments were conducted to identify regions associated with drought tolerance in maize genotypes classified at the seedling stage for this characteristic. To map regions related to tolerance to water deficit (quantitative trait locos, QTL), 205 individuals belonging to two F2 segregating populations obtained from the crossing of two parental lines P1 (tolerant) and P2 (intolerant) were used. Seeds from these individuals were subjected to water deficit induced by PEG 6000 (-0.6MPa), and germination was evaluated 5 days after sowing and subsequently classified by level of tolerance to water deficit (tolerant, intermediate and intolerant) depending on development of the seedlings. For genotyping, SSR microsatellite markers located close to QTLs for this trait were selected according to literature data. Genomic DNA was extracted by the CTAB method and PCR products were separated by capillary electrophoresis. The analyzed populations segregated as 1 (tolerant): 2 (intermediate): 1 (intolerant), indicating a Mendelian segregation model. Data analyzes of each SSR marker in the progenies were carried out using the Cervus and InfoGen software, while the association analysis was carried out using the InfoGen program. Significant associations of phenotypic and genotypic data were detected for markers bnlg1208 and phi027. Using bioinformatics tools and in silico analyzes at the two locos associated with tolerance to drought six genes were identified that could be the target of future studies, being potential markers for early selection assisted markers (MAS) in corn breeding programs and that have functions related to drought tolerance.