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The gene for fragrance in rice

L.M.T Bradbury, T.L. Fitzgerald, R.J. Henry, Q. Jin, D.L.E. Waters

1Southern Cross University, Lismore, Australia, 2 Grainfoods CRC, Sydney, Australia

Abstract

Fragrance in Basmati and Jasmine style rice is due to accumulation of 2-acetyl-1-pyrroline, a chemical also found, to a much lesser extent, in non fragrant rices. Previous genetic studies have linked this trait to a recessive gene (fgr) on chromosome 8 of rice. Our studies show that a gene with homology to betaine aldehyde dehydrogenase (BAD) has significant polymorphisms in the coding region of fragrant genotypes relative to non fragrant genotypes. Accumulation of 2-acetyl-1-pyrroline in fragrant rice genotypes may be explained by the presence of mutations resulting in loss of function of the fgr gene product. The allele in fragrant genotypes has an 8bp deletion and 3 SNPs, introducing a stop codon upstream of important amino acid sequences conserved in other BADs. We also show that fragrance in a wide range of domesticated rices, including traditional Basmati and Jasmine rices, originated from a common fragrant ancestor and may have evolved in a genetically isolated population or be the outcome of a separate rice domestication event. This is an example of effective human selection for a recessive trait during domestication.

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