Toshinori abe, Yoshikage kawauchi and Takeo sasahara
Plant Breeding Laboratory, Faculty of Agriculture, Yamagata University, Tsuruoka, 997, Japan
The classification and evolutionary characterization of rice subspecies, indica and japonica, has been studied mainly based on morphological and biochemical traits including isozymes (Morishima and Oka 1981). Recently, RFLP analysis has been shown to be useful for classification of rice cultivars. Chloroplast and mitochondrial DNAs differed between indica and japonica subspeciese. (Dally and Second 1990; Ishii and Tsunewaki 1989; Second and Wang 1992). The present paper aims to identify critical mtDNA makers for characterization of rice subspecies.
RFLPs of mtDNA were investigated using 44 rice varieties including indica, japonica and javanica subspecies, and one strain of 0. glaberrima. Total DNA was digested Hind III or Xba 1. RFLPs were visualized by Southern hybridization with non-radioactive mtDNA probes labeled with digoxigenin-dUTP. After agarose gel electrophoresis and blotting the separated DNAs onto nylon membrane, they were hybridized with eight mtDNA probes. Mitochondrial DNA probes used were atpA, atp6, atp9, coxl, coxIl, cob, rrnl8 and rrn26 from a rice cultivar, Nipponbare (lwahashi et al. 1992).
When the probes of atp6 and rrnl8 were used, RFLPs
could be detected (Fig. 1 and 2). Atp6 patterns showed that rice
cultivars were classified into four types (I, II, III and IV), and rrnl8
patterns showed that they were classsified into two types (type I and II).
Table I shows the mtDNA patterns of 44 cultivars of 0. sativa and
one strain of 0. glaberrima detected with two mtDNA probes. Differences
of the mtDNA patterns between japonica and typical indica
were recognized. Almost all the japonica and javanica cultivars
and some indica cultivars showed type I in both the atp6
and rrnl8 patterns, whereas many indica cultivars were type
II in both probes. It is noteworthy that some cultivars (Ambar, BlueBelle,
British Honduras Creole and Zenith) which were classified as indica
type because of their grain shape and plant statues showed type I in the
both probes, the same as the type of japonica. In type I of atp6
patterns, one Hind III fragment (8.6 kb) was found, whereas two
fragments (8.6 and 6.9 kb) were observed in type II. Silewah included in
javanica
cultivar group showed a different pattern and was designated as type III
which has the two fragments (8,6 and 7.4 kb). However, two
indica
cultivars (Chinsura Boro II and Gaiya Dhan Tosar) showed another pattern
and
DNA with a probe of rrnl8 (Sma I I-digested total DNA in cultivated rice.
Rice Genetics Newsletter Vol. 13
Table 1. Classification of rice subspecies, indica, japonica and javanica based on the RFLP of
Cultivar | Probe | Cultivar | Probe | ||
atp6 | rrn18 | Atp6 | rrn18 | ||
japonica | indica | II | II | ||
Aikoku | I | I | Boushitou | II | II |
Kiyonishiki | I | I | Josaeng Tongil | II | II |
Koshihikari | I | I | Kinandang | II | II |
Kamenoo | I | I | Panbira | II | II |
Kinmaze | I | I | Te-tep | II | II |
Nipponbare | I | I | Tadukan | II | II |
Norin 1 | I | I | Chinsura Boro II | IV | I |
Reirnei | I | I | Ambar | I | I |
Sasanishiki | I | I | BlueBell | I | I |
Sakaikaneko | I | I | British Honduras Creole | I | I |
Somewake | I | I | Zenith | I | I |
Senshou | I | I | Gaiya Dhan Tosar | IV | I |
Taichung 65 | I | I | |||
Toyonishiki | I | I | javanica | ||
Yoneshiro | I | I | Arditane | I | I |
Calrose | I | I | Lady Wright | I | I |
Choukoutou | I | I | Lomelto | I | I |
Rinnatto | I | I | |||
indica | Rizzotto | I | I | ||
Akamai | II | II | Secia | I | I |
Dee-geo-woo-gen | II | II | Senatore | I | I |
Taichung Native 1 | II | II | Stripe 136 | I | I |
Dojinkyo | II | II | Stripe 136 anthocyane | I | I |
Konansou | II | II | Silewah | III | I |
Konansen | II | II | |||
0. glaberrima | |||||
W0440 | II | II |
Acknowledgments
The authors thank Prof. A. Hirai, and Dr. M. Nakazono, Laboratory of Radiation Genetics, Faculty of Agriculture, The University of Tokyo, for providing the mtDNA clones. The authors also thank Prof. H. Morishima, National Institute of Genetics, for providing seeds of 0. glaberrima strain. W0440 and for her valuable advice.
Dally A.M. and G. Second, 1988. Chloroplast DNA diversity in wild and cultivated species of rice (Genus Oryza. section Oryza). Cladistic-mutation and genetic-distance analysis. Theor Appl Genet 80: 209-222.
Ishii, T., T. Terachi, N. Mori and K. Tsunewaki, 1993. Comparative study on the chloroplast, mitochondrial and nuclear genome differentiation in two cultivated rice species, 0. sativa and 0. glaberrima, by RFLP analyases. Theor Appl Genet 86: 88-96.