| Gene duplication and loss promote the formation of species barrier - Important role of DPL genes for rice evolution. | ||
| Proc. Natl. Acad. Sci. November 23, 2010 | ||
| Kurata Laboratory, Plant Genetics | ||
| Rice pollen hybrid incompatibility caused by reciprocal gene loss of duplicated genes. Mizuta Y, Harushima Y, Kurata N. Proc. Natl. Acad. Sci. Vol.47, page 20417-20422. (2010). published ahead of print November 23, 2010, doi:10.1073/pnas.1003124107 Identification of genes responsible for genetic incompatibility between two species provides insight into molecular mechanisms of reproductive isolation and species diversification. Asian cultivated rice, Oryza sativa has diverged subspecies, indica and japonica . Inter-subspecific crosses between them exhibit various genetic incompatibilities, however, these mechanisms are still largely unknown. A whole genome survey of two-way interacting loci was performed in an F2 population from an inter-subspecific cross between indica cv. Kasalath and japonica cv. Nipponbare. Only one reproducible interaction was detected between loci on chromosomes 1 and 6, and combination of the Kasalath allele on chromosome 1 and the Nipponbare allele on chromosome 6 was not transmitted by pollen. Map-based cloning identified the causal genes as duplicated genes, DOPPELGANGER1 ( DPL1 ) and DOPPELGANGER2 ( DPL2 ). DPLs encode highly conserved plant specific proteins (～10 kDa) of unknown function. Disruptions of DPL1 by a transposable element insertion and DPL2 by a splicing defect occurred independently in indica and japonica , respectively. Pollen carrying two defective DPL alleles became non-functional and did not germinate (Figure). Phylogenetic analyses of DPLs suggested that this gene duplication occurred after Oryza-Brachypodium differentiation; loss-of-function mutations of DPL1 genes emerged in indica and its wild ancestor, O. rufipogon ; and the DPL2 gene defect is specific to japonica cultivars. This research has been selected as the cover of PNAS Issue 47. Financial support was provided by a Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology, Japan, and a Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists.
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