Introgression of Three Heading Date Genes, hd1, Hd6, and ehd1, to Oryza sativa L. japonica cv. Koshihikari by Marker-Assisted Selection
Date Issued
2009
Date
2009
Author(s)
Chen, Cheng-Sheng
Abstract
The heading date of rice is the responds to diverse adaptation to different geographical distributions and seasons. The heading date also influences the rice vegetative stage, in which short vegetative stages reduce grain yield and quality. The elite rice cultivar, Koshihikari, possesses good yield and quality while planted in Japan; however, Koshihikari heads too early while planted by in Taiwan because of its photoperiod-sensitivity. A Taiwan elite cultivar, TNG67 is a photoperiod- insensitve variety and has been widely used as a priority germplam in rice breeding programs in Taiwan. Sequence alignment analyses of six cloned heading date genes between Koshihikari and TNG67 reveal that three heading date genes, Hd1, Hd6, and Ehd1, differ in sequence and function, accounting the variation of days to head in Koshihikari and TNG67. Therefore, the main goal of this study is to introgress the three heading date genes of TNG67 to Koshihikari by MAS, and finally to establish several NILs of Koshihikari with different heading dates, suitably cultivated in Taiwan. According to the sequence variation of the three heading date genes, we designed three functional markers for foreground selection, which Hd1, Hd6, and Ehd1 were designed as indel, CAPs, and dCAPs markers, respectively. A total of 87 polymorphic markers of SSRs and indels, with an average distance of 17.3 cM, were employed as background selection. In the backcross recurrent selection, Koshihikar was served as the recurernt parent, and TNG67 was served as the donor parent. In each backcross generation, the three functional markers of heading date genes were used first to select individuals with Hd1hd1 / Hd6hd6 / Ehd1ehd1 for foreground selection, and then the selected individuals were subjected with various polymorphic markers for background selection. Three individuals selected from 283 BC1F1 by MAS were served as the male parents to backcross to Koshihikari; four individuals selected from64 BC2F1 by MAS were served as the male parents to backcross to Koshihikari; two individuals selected from 246 BC3F1 by MAS, which ＃286-14-A23 and ＃286-85-A27 possess Hd1hd1 / Hd6hd6 / Ehd1ehd1, and contain 92.6％ and 90.8％ of Koshihikari genome, respectively. Upto now, two BC3F1 individuals, ＃286-14-A23 and ＃286-85-A27, were selfed to establish BC3F2 and were served as the male parents to backcross to Koshihikari to establish BC4F1. In the future, sereval NILs of Koshihikari by furher MAS will be established and be evaluated for grain quality, yield and other agronomic traits. Finally, the optimized NILs will be promoted to cultivate in Taiwan.
Subjects
Koshihikar
Tainung 67
heading date
photoperiod
marker-assisted selection
Type
thesis
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