Vol. 20 >B. Research Notes>IV. Genetics of physiological traits and others |
32. | QTL analysis for floating ability in rice |
R. KAWANO1,2, T. MOCHIZUKI2, H. YASUI1, K. DOI1 and A. YOSHIMURA1 1) Plant Breeding Laboratory, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, 812-8581 Japan 2) Agricultural Ecology Laboratory, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, 812-8581 Japan |
Floating ability was characterized mainly by two factors, starting time
of internodal elongation and the ability to elongate internode along with
increasing water depth (Inouye 1987). In most of previous reports on genetics
of deepwater rice, however, floating ability was evaluated without separating
these two factors. Therefore, QTL analysis for floating ability of rice
was performed using two parameters; position of the lowest elongated internode
(LEI) (Inouye et al. 1978) and rate of internodal elongation (RIE)
(Takahashi and Mochizuki 2000) in this study.
plant in a tank with 2 m depth of water. The treatment was
continued for 3 weeks. When the plants reached the bottom of the tank
in less than 3 weeks, the treatment was ended. For adjustment of water
level, one-half of the uppermost fully-expanded leaf blade on main culm
in each plant was maintained to be emerged from water. Internode lengths
were measured at the start and end of the treatment, and RIE was calculated
as follows; RIE (cm d-1) = (B-A) / C, where A; initial
internode length, B; final internode length, C; days for treatment. Genotyping
of the F2 population was done using 93 RFLP and 21 SSR markers.
The linkage map was constructed using MAPMAKER/EXP v. 3.0 (Lander et
al. 1987), and QTL analysis was performed with QTL Cartographer v.
1.16c (Basten et al. 2002). Both simple interval mapping (SIM)
and composite interval mapping (CIM) techniques were used. QTLs for LEI
position and RIE were declared significant at the threshold of 1% level
with the LOD score higher than 3.4, given by 5000 permutations.
that of T65. Frequency distributions for LEI position and
RIE of the F2 population were shown in Fig. 1. The linkage
map covering the whole genome was constructed with an average marker interval
of 15.3 cM (Fig. 2). Two QTLs for LEI position were detected on chromosomes
3 and 12, and explained 79.3% of phenotypic variance. For RIE, two QTLs
were detected on chromosomes 1 and 12, and explained 49.7% of phenotypic
variance. These QTLs were identified by using SIM. CIM technique did not
give further QTL. In all QTLs, Bhadua alleles increased floating ability
(Table 1). |
Vol. 20 >B. Research Notes>IV. Genetics of physiological traits and others |