F. Research Notes

I. Wild species, evolution and chromosome studies

1. Phylogenetic study of A-genome species of genus Oryza using nuclear RFLP
        Kazuyuki Doi1, Atsushi Yoshimura1, Mutsuko Nakano1, Nobuo Iwata1
        and Duncan A. Vaughan2

1) Plant Breeding Laboratory, Faculty of Agriculture. Kyushu University. Fukuoka 812-81, Japan

2) National Institute of Agrobiological Resources. Tsukuba 305, Japan

     RFLP of 67 accessions in the genus Orya, which contains annual 0. rufipogon, perennial 0. rufipogon, 0. nivara, 0. glaberrima, 0. barthii, 0. longistaminata. 0. glumaepatula and 0. meridionalis (Fig. 1) were analyzed, in addition to the materials previously analyzed by Nakano et al. (1992). As a result, 192 accessions from A-genome species were subjected to data analysis.
    RFLPs were detected for combinations of Dra I-digested total DNA and single copy genomic clone (Saito et al. 1991). Each fragment was treated as a unit character, and genetic distances between accessions were quantified as follows: D= - In [2Mxy/( mx + My )], where mx and My were the numbers of total fragments in accessions X and Y. respectively, and Mxy was the number of common fragments observed between accessions X and Y. This formula is based upon Nei's standard genetic distance (Nei 1987, pp. 190-191 foumula 9.24) and ignoring within-accession variation. A dendrogram was then constructed using the UPGMA method (Sokal and Michener 1958).

A dendrogram constructed by using 76 accessions including 12 accessions previously analyzed is shown in Fig. 1. A-genome species were classified into major groups. Asian group (0. sativa. 0. rufipogon and (O. nivara). 0. glumaepatula group, 0. glaberrima + 0. barthii group, 0. longistaminata group and 0. meridionalis group. 0. glumaepatula had closer affinity with 0. glaberrima + 0. barthii group than with Asian 0. rufipogon. although they had been considered to be a subtype of 0. rufipogon. Except for this. relationship among species matched well with previous studies.

Asian group which contains 0. sativa, 0. rufipogon and 0. nivara consisted of loosely knitted four or five groups, each corresponding to Indica (including some (9. rufipogon), Japonica (including some 0. rufipogon), 0. rufipogon (consisting of several groups) and 0. nivara (Fig. 1). There is a need for further analysis to determine the relationships of these sub-groups.

Three accessions of perennial 0. rufipogon from Papua New Guinea (excluded from Fig. 1 ) carried both fragments of (O. rufipogon and 0. meridionalis, suggesting the occurrence of natural hybridization between the species.

 
Fig. 1. RFLP-derived dendrogram of 76 accessions. RFLPs were detected with 21 genomic clones. 12 accessions of 0. sativa, 0. rufipogon and 0. glalberrimai previously analyzed (Nakano et al. 1992) are included. 67 accessions analyzed in this study were kindly provided by the International Rice Germplasm Center (IRGC). IRRI. Out of 67. 3 from Papua New Guinea are excluded in this figure.1 ) True perennial type of O. rufipogon.
 

References

Nakano, M.. A. Yoshimura and N. lwata. 1992. Phylogenetic study of cultivated rice and its wild relatives by
        RFLP. Rice Genet. Newslett. 9: 132-134.
Nei. M.. 1990. Molecular Evolutionary Genetics. BAIFUKAN. Tokyo. (Japanese)
Saito, A.. M. Yano, N. Kishimoto, M. Nakagahra, A. Yoshimura, K. Saito, S. Kuhara, Y. Ukai, M. Kawase, T. Nagamine, S.
        Yoshimura, O. Ideta, R. Ohsawa, Y. Hayano, N. Iwata and M. Sugiuru. 1991. Linkage map of restriction fragment length
         polymorphism loci in rice. Japan. J. Breed. 41: 665-670.
Sokal, R. R. and C. D. Michener. 1958. A statistical method for evaluating systematic relationships. Sci. Bull..
        University of Kansas 38: 1409-1438.