Effects of Rice Heading Date Genes under Natural Day Length in Taiwan
Date Issued
2015
Date
2015
Author(s)
Yen, Wei-Hsuan
Abstract
Rice (Oryza sativa) is considered a short day plant. World-wide adaptation of rice maybe attributed to complicate mechanism of photoperiodic response and variation of heading date genes. Taiwan is located at the southern border and the northern border of the region where temperate Japonica rice and Indica rice are grown, while the natural day length in Taiwan lies between the typical definition of “short day” and “long day” in previous studies. Since some flowering time genes perform differently under distinct area, heading date gene expression in Taiwan may not conform to these studies. In this study, heading date QTL mapping data in Taiwan was reanalyzed and the genotypes of Taiwan cultivars were investigated, including heading date genes Ehd1, Hd1, Ehd4/Dth3, Ghd7 and Dth2. Hd1 is a bi-functional gene that represses flowering under long day length but promotes flowering under short day length environment. The effect of Hd1 in Taiwan is limited because of the day length coincides with the threshold day length of bi-functional Hd1gene, and most alleles of Taiwan cultivars are non-functional. Ehd1 plays an important role in the flowering pathway and the allele ehd1-T65 is a unique allele of Japonica cultivars in Taiwan. Alleles of Ehd4/Dth3, Ghd7 are separated among rice subspecies, indicating difference of flowering pathways between Japonica and Indica. The understanding of effects and mechanisms of heading date genes has led to a successful development of variety, Tainan 16. The identification of specific alleles among production regions may be used to discriminate the rice imported abroad from local produced rice. In the future, the knowledge of rice heading date may be used to breed for cultivars with late heading dates in order to take the full advantage of the new concept of single crop season for rice in Taiwan, which may be an answer to the problem of rice over-production and water shortage in spring.
Subjects
Oryza sativa L
Heading date
Regression
Type
thesis
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