Growth duration or heading date is one of the important agronomic traits of rice. Identification and location of heading date genes in rice have significant application values. Dominant earliness trait was identified in a indiea-japoniea medium type of line H14. The heading date of F1 progenies from H14 crossed with various types of medium- or late-maturlng varieties shared the same heading date as H14 or was earlier. Meanwhile, the heading dates of individual plants distributed bimodally in the F2 populations from the crosses between H14 and two late-maturing varieties, i.e., Minghui 63 and Shuhui 881, and in the B1F1 populations from the crosses between the F plants and their late-maturing parents. The individuals in each segregating populations could be classified into two groups, early heading and late heading, according to the heading date distribution profile. The segregation ratio of early heading plants to late heading plants fitted the ratio of 3：1 in the F2 populations and 1：1 in the B1F2 populations. The results suggested that the earliness trait of H14 was mainly controlled by one dominant major gene. The local linkage map of the dominant earliness gene harbored in H14 was constructed with F2 population of H4 crossed with Minghui 63. Using microsatellite marker technique, the dominant earliness gene was located on one side of two microsatellite markers, RM314 and RM276, on the short arm of rice chromosome 6, with genetic distances of 8.2cM from RM314. This gene is considered to be a new dominant earliness gene in rice and designated tentatively as Ef-h（t）.
Chinese Journal of Applied and Environmental Biology
教育部长江学者和创新团队发展计划（IRT0453）资助项日和曲阜师范大学校科研启动基金（2003）资助项目 致谢 感谢云南农业大学曾千春博士提供水稻试验材料“H14”.
rice （Oryza sativa L.）
dominant earliness gene