Enhancement of genetic exchange in maize: Intragenic recombination

Intragenic recombination is enhanced by two metal complexing agents, EDTA (Ethylene diaminetetra acetic acid) and kryptofix 222 (E. Merck Laboratory). The assay system included heteroallelic combinations of three wx alleles, wx-B, wx-C, and wx-90 on normal and homozygous interchanged chromosomes.

Spray treatment with solutions of these two chemicals resulted in a higher frequency (significant at the .05 level) of recombination (as judged from the occurrence of Wx pollen grains from wx-a/wx-b heteroalleles). Sample data comparing the effects of treatments (water, control) EDTA and kryptofix on Wx frequencies per 105 in various wx heteroallelic combinations:
Genotype Control EDTA Kryp
N-B/C 42.34 55.62 48.52
N-C/90 106.88 115.17 114.11
T5C/90 66.11 72.45 74.44
Mean 71.78 81.08* 79.02*

*Significant at 0.05 level.

There were two chromosome arrangements for these heteroalleles: the normal and the chromosome interchange whereby the wx locus was moved a further distance away from the centromere. Greater distances away from the centromere resulted in higher frequencies of intragenic recombination but less than those of the standard chromosome even though in some of the interchange chromosomes, the centromere-wx distance was greater.

Kitsiri Sukhapinda and Peter A. Peterson

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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