Cassava haplotype map highlights fixation of deleterious mutations during clonal propagation
Fei Lu, Punna Ramu and colleagues construct a cassava haplotype map (HapMapII) by using deep-sequencing data from 241 accessions and identify over 28 million segregating variants. They find that clonal propagation has led to fixation of deleterious mutations, which have been ineffectively purged, ow...
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Veröffentlicht in: | Nature genetics 2017-06, Vol.49 (6), p.959-963 |
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Zusammenfassung: | Fei Lu, Punna Ramu and colleagues construct a cassava haplotype map (HapMapII) by using deep-sequencing data from 241 accessions and identify over 28 million segregating variants. They find that clonal propagation has led to fixation of deleterious mutations, which have been ineffectively purged, owing to limited recombination
Cassava (
Manihot esculenta
Crantz) is an important staple food crop in Africa and South America; however, ubiquitous deleterious mutations may severely decrease its fitness. To evaluate these deleterious mutations, we constructed a cassava haplotype map through deep sequencing 241 diverse accessions and identified >28 million segregating variants. We found that (i) although domestication has modified starch and ketone metabolism pathways to allow for human consumption, the concomitant bottleneck and clonal propagation have resulted in a large proportion of fixed deleterious amino acid changes, increased the number of deleterious alleles by 26%, and shifted the mutational burden toward common variants; (ii) deleterious mutations have been ineffectively purged, owing to limited recombination in the cassava genome; (iii) recent breeding efforts have maintained yield by masking the most damaging recessive mutations in the heterozygous state but have been unable to purge the mutation burden; such purging should be a key target in future cassava breeding. |
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ISSN: | 1061-4036 1546-1718 |
DOI: | 10.1038/ng.3845 |