Analysis of genetic recombination in maize populations using molecular markers

Abstract

Variation in recombination rate is important to plant breeders since a major objective is to obtain favorable recombinants of linked genes. The ability to increase recombination (R) in circumstances in which favorable and unvavorable genes are linked (Corn Belt x exotic populations) and to decrease recombination when many favorable genes are linked (narrow-based, elite populations) would be of immense value. However, the concept of variation in recombination frequencies between linked genes has received limited attention despite its implications in breeding and genetic linkage studies. Molecular techniques have allowed better estimations of this variation. In this study, attempts were made to characterize: (1) the R values in the Pgm1-Adh1 and Adh1-Phi1 adjacent regions of chromosome 1 and the Idh2-Mdh2 region of chromosome 6 in F2 families of three maize (Zea mays L.) populations; (2) the environmental effect on R values of F2s from two populations. One population, NSO, was a Corn Belt synthetic, and the other two populations, CBMEX3 and CBCAR5, were composites from crosses between Corn Belt and exotic germ-plams.Wide ranges of estimated recombination ([Formula: see text]) values were observed among families in each population for all three chromsomal regions. The distribution of [Formula: see text] values for the Pgm1-Adh1 region showed that the F2 families of each population fell into two broad categories: 0.30-0.50 and 0.02-0.20. No intermediates (0.21-0.29) were found. The distributions were almost normal for the Adh1-Phi1 and the Idh2-Mdh2 regions. It would appear that the major dispersion in the Pgm1-Adh1 region was controlled by the effects of a single gene, while the Adh1-Phi1 and Idh2-Mdh2 regions were only affected by polygenes. No correlation was found between recombination values of the two adjacent regions, indicating that the genes affecting recombination for the Pgm1-Adh1 region may be specific for that region.For the Pgm1-Adh1 region, no differences in [Formula: see text] values were found among the three populations. For the Adh1-Phi1 region, [Formula: see text] frequencies of CBMEX3 and NSO were not significantly different, but both had significantly greater [Formula: see text] values than CBCAR5. For the Idh2-Mdh2 region, CBMEX3 was significantly different from NSO. There were significant differences between some paired F2 families within each population for each chromosome region.No significant differences in response to the two environments were detected in CBMEX3 and NSO for either region in chromosome 1.

High segregation distortion in maize B73 x teosinte crosses

“…The map length of an interspecific hybrid has been recognized as being shorter than that of an intraspecific hybrid Stec, 1991, 1993). Variability in recombination rates in maize was first reported in 1918 by Bregger and later confirmed using molecular markers (Tulsieram et al, 1992). Segregation distortion was first reported in maize by Mangelsdorf and Jones (1926) based on a linkage between the gametophyte factor Ga1 and the Su allele for starchy endosperm.…”

“…A study by Tulsieram et al (1992) suggested that cis-factors potentially influence recombination rates. The first explanation for recombination shrinkage was based on the assumption that base-sequence homology determines where crossing-over will occur (Borts and Haber, 1987).…”

Recombination rate differences for pollen parents and seed parents in Pinus pinaster

“…Recombination fraction can also vary depending on the environment (Ihrke & Kronstad, 1975;Zhuchenko & Korol, 1983). The influence of temperature has been particularly studied and reported (Allard, 1963;Towe & Stadler, 1964;Lu, 1974;Rose & Baillie, 1979;Tulsieram et a!., 1992). These examples of recombination differences raise several problems concerning the extent of heterogeneity and its potential impact on map merging, breeding applications, and positional cloning.…”

Effects of trans-acting Genetic Modifiers on Meiotic Recombination Across the a1–sh2 Interval of Maize

“…In Arabidopsis, recombination rates vary among accessions (Sanchez-Moran et al 2002). In maize, heterogeneity in recombination frequencies has been well documented within corn belt (Beavis and Grant 1991;Tulsieram et al 1992), corn belt 3 exotic germplasm (Tulsieram et al 1992), synthetic (Fatmi et al 1993), exotic, and teosinte-maize hybrid (Williams et al 1995) mapping populations and has often confounded the generation of composite genetic maps. Recombination rates in intervals with heterogenous frequencies varied two-to threefold among diverse mapping populations (Williams et al 1995).…”