|Vol. 18 >C. Research Notes>III. Genetics of physiological traits and others|
|23.||A new gene for F1 pollen sterility located on chromosome 12 in Japonica / Indica cross of rice|
|T. KUBO, M. EGUCHI and A. YOSHIMURA
Plant Breeding Laboratory, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, 812-8581 Japan
|F1 hybrids between Japonica and Indica rice varieties
show various degrees of pollen and spikelet sterility. Although a large
number of studies have been made on hybrid sterility, many sterility genes
have not been fully investigated. During the process of developing Indica
chromosome segment substitution lines with Japonica genetic background (Kubo
et al. 1999), we observed segregation of hybrid sterility. In this
study, we identified a gene responsible for F1 pollen sterility
and mapped it on RFLP linkage map.
We developed IR24 (Indica variety) chromosome segment substitution lines (CSSLs)
with Asominori (Japonica variety) genetic background by successive backcrossing
and marker-assisted selections (Kubo et al. 1999). Segregations
of pollen sterility were observed in some of the BC3F2
and BC3F3 populations. To identify and map the causal
gene, a segregating BC5F1 population (N=73) derived
from backcrossing a substitution line of chromosome 12 with Asominori
was used to evaluate pollen fertility and perform RFLP analysis. The BC5F1
population clearly segregated into two groups: pollen fertile (more than
95%) and semi-sterile (20- 65%), with a total of 41 and 32 plants, respectively
This segregation fitted to the theoretical 1:1 ratio (chi2
=1.11) based on a single nuclear gene. The gene for pollen sterility was
designated as S25(t). RFLP analysis in BC5F1
population showed that the fertile and semi-sterile plants were Asominori
homozygous and heterozygous alleles, respectively, at G193 on chromosome
12. Thus, S25(t) caused pollen semi-sterility in heterozygous condition
and co-segregated with G193. Linkage analysis using other RFLP
markers at the region showed that S25(t) was located between G24
and G189 with a map distance of 1.4cM and 5.5cM, respectively (Fig.
This study was supported by Bio-oriented Technology Research Advancement Institution (BRAIN), Japan.
Harushima, Y., M. Yano, A. Shomura, M. Sato, T. Shimano, Y. Kuboki, T. Yamamoto, S.Y. Lin, B.A. Antonio, A. Parco, H. Kajiya, N. Huang, K. Yamamoto, Y. Nagamura, N. Kurata, G.S. Khush and T. Sasaki, 1998. A high-density rice genetic linkage map with 2275 markers using a single F2 population. Genetics 148: 479-494.
Kubo, T., K. Nakamura and A. Yoshimura, 1999. Development of a series of Indica chromosome segment substitution lines in Japonica background of rice. RGN 16: 104-106.
|Vol. 18>C. Research Notes> III. Genetics of physiological traits and others|