Teosinte Cytoplasmic Genomes: II. Performance of Maize Hybrids with Teosinte Cytoplasms
- Jode W. Edwards and
- James G. Coors
Alien cytoplasm substitution effects on quantitative agronomic characters in maize breeding germplasm have been studied many times, but few cytoplasmic effects have been found. This research was conducted to evaluate the importance of nuclear sources of variation often confounded with cytoplasmic effects, and to study effects of substituting teosinte cytoplasms into Zea mays ssp. mays hybrids. Cytolines were developed by transferring 11 cytoplasms to maize inbreds A619 and W23 by at least six generations of backcrossing. Reciprocal testcrosses were made between cytolines and three testers as well as between A619 and W23 and the same testers. Nuclear effects on reciprocal cross differences and effects of incomplete recovery of cytoline nuclear genotypes were large enough to cause bias in estimates of cytoplasmic effects, had appropriate comparisons not been available to account for these sources of variation. The 11 teosinte cytoplasms reduced grain yield by an average of 0.20 Mg ha−1 or 2.2%. Cytoplasmic effects averaged across all cytoplasms and hybrids were not significantly different from zero for any other trait. One of 11 cytoplasms studied had stable effects on hybrid performance. Four additional cytoplasms had appreciable effects that varied widely with the nuclear genotype. Direct substitution of any of these cytoplasms into maize hybrids would not likely be of great benefit because desirable effects were generally small and difficult to predict in different nuclear-cytoplasmic combinations.
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