45. Development of Oryza glumaepatula introgression lines
in rice, 0. sativa L.
Sobrizal1, K. IKEDA1, P.L. SANCHEZ’, K. Doi’, E.R. ANGELES2,
G.S. Khush2 and A. Yoshimura1
1) Plant Breeding Laboratory, Faculty of Agriculture, Kyushu
University, Fukuoka, 812-8581 Japan.
2) International Rice Research Institute, Manila, Philippines
The wild species Oryza glumaepatula
Steud. is distributed in central and south America and Caribbean (Vaughan
1983). This species is distributed widely in the Amazon basin, Brazil and
is adapted to flooded conditions (Akimoto et a!. 1998). Like other common
wild rice 0. rufipogon, 0. glumaepatula differs from cultivated rice, 0.
sativa L. in morphology, environmental adaptability and growth habit. To
analyze the genetics of traits specific to 0. g!umaepatula and to exploit
the genetic potential of this species, we attempted to develop series of
0. glumaepatu!a introgression lines (glumlLs) with 0. sativa L. cv.Taichung
65 and 0. glumaepatu!a cytoplasms in the genetic background of 0. sativa
L. cv. Taichung 65.
For developing glumlLs, F, seeds
were obtained through the reciprocal crosses between 0. glumaepatula (Acc.
IRGC 105668) and Taichung 65. The resultant F, plants served as female
parents and were continuously backcrossed with Taichung 65 to generate
the BC4FI populations. To select the plants having desired genotypes, whole
genome survey was conducted in BC3F1 generation by using 106 RFLP markers
scattered in 12 chromosomes. Selections in BC4F, generation were made on
the basis of observation of genotypes of the target regions only.
Out of 103 BC3F, plants having 0.
glumaepatula cytoplasm, 27 were selected based on the introgressed segment
in the target regions. Out of 167 BC4FI plants derived from 27 selected
BC3F, progenies, 63 promising plants canying both cytoplasm and entire
chromosome segments of 0. glumaepatula were selected as candidates for
glumlLs with 0. glumaepatula cytoplasm. In the same manner, out of 83 BC3F1
plants having Taichung 65 cytoplasm, 36 plants were selected. Out of 184
BC4F1 plants derived from 36 selected BC3F1 progenies, 84 promising plants
carrying Taichung 65 cytoplasm and entire chromosome segments of 0. glumaepatu!a
were selected as candidates for glumlLs with Taichung 65 cytoplasm.
The representation of introgressed
chromosome segments in sub-sets (34 plants having Taichung 65 cytoplasm
and 25 plants having 0. glumaepatula cytoplasm) are shown in Fig. 1. Most
part of the 0. glumaepatula genome was covered, except the regions marked
with arrows. In the region around RFLP marker C1115, 0. glumaepatula genotypes
were observed in almost all promising plants having 0. glumaepatula cytoplasm.
This region involved hybrid weakness restoration locus (Rhw) reported by
Ikeda et a!. (1999).
These glumlLs are a good source
of genetic materials for detailed analysis of special traits of 0. glumaepatula
and for evaluating various morpho-agronomic characters of hybrid progenies.
Selfing of BC4F,s and further selections are underway to fix and obtain
a complete set of glumlLs.
This study was supported in part
by Bio-oriented Technology Research Advancement Institution (BRAIN), Japan.
Sobrizal and K. Ikeda were supported by postdoctoral fellowships from BRAIN,
Japan.
Akimoto, M., Y. Shimamoto and H. Morishima, 1998. Population
genetic structure of wild rice Oryza glumaepatula distributed in the Amazon
flood area influenced by its life-history traits. Molecular Ecology7: 1371-1381.
Ikeda, K., Sobrizal, P. L. Sanchez, H. Yasui and A. Yoshimura,
1999. Hybrid weakness restoration gene (Rhw) for Oryza glumaepatula cytoplasm.
Rice Genetic Newsletter 16 (in press).
Vaughan, D., 1989. The genus Oryza L. current status of
taxonomy. IRRI research paper series No. 138. The International Rice Research
Institute, Manila, Philippines
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