Whole-Genome Sequencing Revealed a Late-Maturing Isogenic Rice Koshihikari Integrated with Hd16 Gene Derived from an Ise Shrine Mutant

Figure 1

Genetic analysis for late maturity derived from Isehikari. (a) Distribution of mean value of heading date and culm length in 70 F₃ lines derived from the cross Koshihikari×Isehikari. Progeny tests were conducted on 70 randomly selected F₂ plants by using self-propagated 70 F₃ lines from each F₂ plant. The genotype of the heading date was determined according to the ratio of 23 late-maturing homozygous lines (tentatively Hd homo; blue) : 26 heterozygous lines (Hdhd; red) : 21 early maturing homozygous lines (hd homo; yellow), which fit to a theoretical single gene ratio of 1 : 2 : 1 (, ). The latest homozygous F₃ line, which was 7 days later than Isehikari, was backcrossed as a nonrecurrent parent with Koshihikari as a recurrent parent. (b) Frequency distribution of heading date in the BC₃F₂ (Koshihikari×3//(Koshihikari/Isehikari F₂). In the BC₃F₂, early maturing plants heading like Koshihikari during 8/12–8/17, midmaturing plants heading during 8/19–8/23, and late-maturing plants heading during 8/26–8/28 segregated in a ratio of 12 early maturations : 28 midmaturations : 10 late maturations, which was well consistent with a theoretical single gene ratio of 1 : 2 : 1 (, ). The semidwarfness derived from Isehikari was segregated independently from late maturity in F₂ and F₃ (a). As the latest homozygote without semidwarfness was used as a nonrecurrent parent, the late maturity was solely segregated in the backcross F₂ (b), and finally, a late-maturing isogenic Koshihikari was developed.

(a)

(b)