Abstract
Knobs are conspicuous heterochromatic regions found on the chromosomes of maize and its relatives. The number, locations, and sizes of knobs vary dramatically, with most lines containing between four and eight knobs in mid-arm positions. Prior data suggest that some knobs may reduce recombination. However, comprehensive tests have not been carried out, primarily because most knobs have not been placed on the genetic map. We used fluorescent in situ hybridization and two recombinant inbred populations to map seven knobs and to accurately place three knobs from the B73 inbred on the genomic sequence assembly. The data show that knobs lie in gene-dense regions of the maize genome. Comparisons to 23 other recombinant inbred populations segregating for knobs at the same sites confirm that large knobs can locally reduce crossing over by as much as twofold on a cM/Mb scale. These effects do not extend beyond regions ~10 cM to either side of knobs and do not appear to affect linkage disequilibrium among genes within and near knob repeat regions of the B73 RefGen_v2 assembly.
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Claims 4
Claim · model-written summary
Mapped maize knobs lie in gene-dense genomic regions.
- Outcome
- knobs lie in gene-dense regionse0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The data show that knobs lie in gene-dense regions of the maize genome”
Claim · model-written summary
Large knobs locally reduce crossing over by as much as twofold on a cM/Mb scale.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“large knobs can locally reduce crossing over by as much as twofold on a cM/Mb scale”
t0“Maize”
Claim · model-written summary
The recombination effect does not extend beyond about 10 cM on either side of knobs.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These effects do not extend beyond regions ~10 cM to either side of knobs”
t0“Maize”
Claim · model-written summary
Knobs do not appear to affect linkage disequilibrium among nearby genes.
- Material
- knob repeat regionse0
- Outcome
- linkage disequilibrium among genese0
- Direction
- do not appear to affecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“do not appear to affect linkage disequilibrium among genes within and near knob repeat regions of the B73 RefGen_v2 assembly”
t0“Maize”