Further selection during crop improvement in genes such as GS3, Bh4, qSW5, wx and Rc also reduced the polymorphisms in the regions associated with these genes. Artificial selection during rice domestication in genes such as sh4, PROG1 resulted in reduced diversity in the adjoining genomic regions due to selection sweeps associated with the genes. Additional selection pressure during domestication and crop improvement resulted in further depauperating the polymorphisms resulting in the ‘polymorphism deserts’ as in the case of chromosome 5 of rice. A predomestication bottleneck possibly induced by environmental stress resulted in loss of polymorphisms in the adaptive genes in case of wild rice. The allelic forms of genes are represented in different colors. ) indicates domestication genes, star shape (*) indicates genes for crop improvement.Despite having closely related sequences in these genome regions, the Australian wild populations represent an invaluable source of diversity supporting rice food security.ĭifferent classes of genes are represented by different shapes dice shape (♦) indicates genes for adaptive traits, circles ( Both the perennial and annual wild rice from Australia show a high degree of conservation of sequence with that found in cultivated rice in the same 4.58 Mbp region on chromosome 5, which suggests that some of the 'polymorphism deserts' in this and other parts of the rice genome may have originated prior to domestication due to natural selection.Īnalysis of genes in the 'polymorphism deserts' indicates that this selection may have been due to biotic or abiotic stress in the environment of early rice relatives. Analysis of the genome of domesticated rice reveals regions of low diversity that show very little variation (polymorphism deserts). Nipponbare shows that Australian wild rices possess 2.5 times more single nucleotide polymorphisms than in the Asian wild rice and cultivated O. Assembly of the resequencing data to the O. We have examined the sequence of the genomes of AA genome wild rices from Australia that are close relatives of cultivated rice through whole genome re-sequencing. Oryza meridionalis is a related annual species in Australia. Oryza rufipogon is a perennial wild progenitor of cultivated rice. Australian wild rices have been isolated from the impacts of domestication in Asia and represents a source of novel diversity for global rice improvement. Wild relatives of crop plants are a source of useful variation which is of immense value for crop improvement. Domestication involved selection of traits that are desirable for agriculture and to human consumers. Rice is a major source of human food with a predominantly Asian production base.
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