Domestication of Rice Land Races Collected in Taiwan Aboriginals Based on Sequence Polymorphism and Expression Variation of Heading Date Genes

Rice (Oryza sativa L.) is one of the major foods in Asia, and it is a short-day plant. During domestication by human selection had made it produced different adaption to the temperate or tropical climate zone and different cultivar types. Researchers had identified several genes responsible for heading date in rice through mutants and chromosome walking. Among those genes, Heading date 3a (Hd3a), Heading date 1 (Hd1), Heading date 6 (Hd6), Photoperiodic sensitivity 5 (SE5), Early heading date 1 (Ehd1), and Early heading date 2 (Ehd2) are the target genes in this study.here are many natural variations in rice heading date gene sequences. In this study, six land races were selected from sixty rice land races collected from Taiwan aboriginals, with heading dates differed about sixty days.The study discovers many DNA sequence variations in these heading date genes among six land races, and some of them may result in amino acid variations. For instance, there are two types of insertions with 36 bp or 123 bp DNA fragments in the first exon of Hd1, and one type of insertions with the 1901bp (a retrotransposon) in the second exon of Hd1, in addition, many SNPs (single nucleotide polymorphism) were also observed.n present study, TILLING (Targeting Induced Local Lesions in Genomes) analysis illustrates many variations in the six heading date related genes of the land races collected from Taiwan aboriginals. Those variations occur at the promoters, UTRs, introns and exons. In the future, we may compare the information with those obtained from land races in the nearby countries through international collaborations. Together with the efforts from archeologists and philologists, we should be able to reveal the rice cultivation of Taiwan during the pre-history period, including rice domestication.