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Analysis of genetic recombination in maize populations using molecular markers
Abstract
An understanding of the inheritance of recombination frequency between linked genes would enhance its use as a tool in plant breeding. The objectives of this study were to: (i) Characterize recombination frequencies in two adjacent segments on chromosome 1 marked by Pgml, Adhl, and Phil isozyme loci, and in one segment on chromosome 6 marked by Idh2 and Mdh2, in three maize populations: CBMEX3 and CBCAR5, derived from corn belt x Mexican and Caribbean germplasm, respectively, and NSO, an unselected corn belt synthetic; (ii) Compare variation in recombination frequencies between populations and between families within populations for each region; (iii) Compare the effect of two environments on recombination rates for the Pgm1-Adh1 and Adh1-Phi1 regions in CBMEX3 and NSO. Recombination values (r) were computed from segregating F$\sb2$ progenies derived from crosses between plants of contrasting genotypes for linked loci in the respective populations. Wide ranges in recombination were observed among families in each population for all regions. For the Pgm1-Adh1 region, F$\sb2$ families of each population fell into two broad categories of r frequencies; $>$0.30-0.49 and 0.02-0.20. No intermediate values (0.21-0.29) were found. For the Adh1-Phi1 and the Idh2-Mdh2 regions, the distribution curves of r frequencies were almost normal. Crossing-over frequencies were apparently controlled by a single gene in the Pgm1-Phi1 region, but by multi genes in the Adh1-Phi1 and Idh2-Mdh2 regions. No correlation was found between r-values of the two adjacent regions in chromosome 1, indicating that the single gene affecting recombination in the Pgm1-Adh1 region may be specific for that region. For the Pgm1-Adh1 region, no difference in mean r value was found among populations while for the Adh1-Phi1, region both CBMEX3 and NSO were significantly different from CBCAR5. For the Idh2-Mdh2 region, CBMEX3 was significantly different from NSO. The other differences between population pairs were not significant. F$\sb2$ families within each population were significantly different for each chromosome region. No significant differences in response to two environments (field, Florida and greenhouse, Nebraska) were detected in CBMEX3 and NSO for the two regions in chromosome 1.
Subject Area
Agronomy
Recommended Citation
Tulsieram, Lomas Kumar, "Analysis of genetic recombination in maize populations using molecular markers" (1989). ETD collection for University of Nebraska-Lincoln. AAI9013630.
https://digitalcommons.unl.edu/dissertations/AAI9013630