Maize is also known as corn in some countries and it is now the third most important cereal crop in the world. Scientists are focusing to develop hybrid varieties with maximum output. Therefore, the understanding of the germplasm and the genetic control for maturation is crucial to optimize the selection of lineages and to boost up the process of development of competitive hybrids. The strength of a maize hybrid is evaluated by the number of days for flowering and the rate of grains water loss after physiological maturity2,3. Therefore, it is of extreme significance to map the genetic factors and to evaluate the gene effects and interactions to permit selection based on genomic information.4
Molecular markers play a key role to study the genetic traits, for detecting polymorphisms directly at the molecular level without impact of environment5. The development of single nucleotide polymorphism (SNP) markers, large-scale genotyping at an affordable cost can be performed. Moreover, novel genetic mapping techniques including association genetics, have been developed through improved computational analysis capabilities. By using association genetics, researchers are capable to map the germplasm without the requirement to generate crossings6.
A study was designed to identify genomic regions for number of days for flowering and loss of moisture after physiological maturity in common maize strains. For linkage disequilibrium mapping, 72 strains were previously genotyped for SNP markers on the 650K platform and their respective genotypic values were predicted for male and female flowering and area below the moisture curve. The analysis of association between the SNPs markers and the characters was performed using mixed linear model and stepwise multiple regression.
The considerable relations; detected for male and female flowering were found to be distributed in all chromosomes, with a higher concentration in genomic regions of chromosomes 1, 2, 3, 5, 9 and 10. For the area below the moisture curve, Scientists observed a smaller number of major links, being concentrated in the chromosomes 1, 2, 3, 6, 9 and 10 and absent in chromosomes 4 and 8. By means of stepwise analysis, complete models were obtained that account for 79, 93 and 56% of the variation for the genotypic values, respectively, with the identification of genomic regions pre-dominantly on chromosomes 1 and 3. Conclusively; this study discovered the importance of genomic regions of tropical maize on chromosomes 1 and 3 for male and female flowering and speed of moisture loss. Still, it is essential to perform the validation in temperate maize germplasm to make the use of these markers in a SAM program feasible.
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17 November, 2019