PLANT BREEDING

Hybrid decay mystery

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Science  27 Sep 2019:
Vol. 365, Issue 6460, pp. 1415
DOI: 10.1126/science.365.6460.1415-a

A red variety of maize, derived from the wild teosinte corn plant first cultivated in Central America 7000 years ago

PHOTO: PHILIPPE PSAILA/SCIENCE SOURCE

Plant breeders seek new combinations of alleles to improve crop performance. While investigating the effects of teosinte genes in a predominantly maize background, Xue et al. obtained a lineage of plants that appeared normal in the first hybrid generation, but subsequent offspring backcrossed into maize exhibited deleterious effects. Genetic analysis of individuals in this lineage showed that this was caused by the propagation of multiple teosinte regions in the maize genetic background, which the authors called hybrid decay. Hybrid decay appeared to be associated with unstable genomic regions and increased copy numbers of repetitive DNA-like transposable elements. Further, expression differences in known genes, short RNAs, and novel transcripts, as well as differences in methylation, were all noticed in the hybrids. It remains to be seen how common hybrid decay is among eukaryotes, and if it is solely the result of effects related to the silence of transposable elements within the genome.

Genetics 213, 143 (2019).

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