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W. B. CHEN1, I. NAKAMURA2, Y.I. SATO2 and H. NAKAI3
1) United Graduate School of Agric. Sciences, Gifu University, Gifts, 501-11 Japan
2) National Institute of Genetics, Mishima, 411 Japan
3) Faculty of Agric., Shizuoka University, Shizuoka, 422 Japan
Chloroplast DNA of indica and japonica rice could be distinguished by some RFLP markers (Second 1990; Ishii et al. 1988). For instance, the fragment of chloroplast DNA (cpDNA) of indica rice Pst-12, a deletion of ca. 100 bp was found to exist (Nakamura and Sato 1991). Since this deletion sequence can be easily detected by PCR amplification of the DNA fragment, it can be used as a valid marker to distinguish the indica (deletion) from japonica (non-deletion). In this paper, we report the relationship between plastotype (cpDNA type) and Z value given by a discriminant function for the indica and japonica types of Chinese cultivated rice, and the geographical distribution of the plastotypes with and without deletion in the common wild rice.
Fig. 1. Amplification patterns of deletion (D) and non- deletion type-specific chloroplast-DNA fragment. 1. T65 (japonica); 2. Ac4l4 (indica); 3. Ch28; 4. Ch26: (O. sativa). 5. W 1965; 6. W 168: (O. rufipogon). 7. CP25 (O. officinalis). 8. W1169; 9. W1167: (O. rufipogon, American form, so-called O. glumaepatura). 10. W1626 (O. meridionalis, or Australian form of O. rufipogon). 11: W 1004 (O. longistaminata).
Plant materials used were 90 Chinese cultivars and 70 strains of wild rice preserved in National Institute of Genetics. DNA extraction and polymerase chain reaction (PCR) were performed as described by Nakamura and Sato (1991). Reaction products were analyzed by 1.5% agarose gel electrophoresis (Fig. 1). In Chinese cultivars, indica and japonica types were classified by the function values (Z) based on morphological and physiological characters as reported by Sato (1991). Varieties with positive Z values or zero were classified as indica, and those with negative Z values as japonica (Table 1).
Forty cultivars with the delection of cpDNAs and 50 cultivars without the deletion were found. These deletion and non-deletion types mostly corresponded to indica and japonica types respectively (Table 1). This serves as an example of nonrandom association as detected by Sato et al. (1990).
Both types of cpDNA fragments, with or without the deletion, were found in the wild species, Oryza rufipogon, O. officinalis, O. longistminata and O. meridionalis, but all distantly related to O. sativa were non-deletion types. The deletion and non-deletion types were differentiated in O. rufipogon. A strain from South America was a deletion plastotype, but two other American wild strains were non-deletion types.
In Asian O. rufipogon, 37 strains of deletion plastotype and 23 strains of non-deletion type were found. Many of non-deletion types were distributed in South China, Burma and West India. In Thailand, Laos and other southeast Asian countries, deletion types were larger in number than non-deletion types. Three deletion types and three non-deletion types were found in Malaysia. A weak relationship in geographical distribution of deletion plastotype was found between the wild rices and indica cultivars.
References
Second, G. 1990. Cytoplasmic DNA markers, phylogeny, and systematics in Oryzeae. Rice Genetics II (ed. IRRI): 475-486.
Ishii, T., T. Terachi and K. Tsunewaki, 1988. Restriction endonuclease analysis of chloroplast DNA from A-genome diploid species of rice. Jpn. J. Genet. 63: 523-536.
Nakamura, I. and Y.I. Sato, 1991. Analysis of chloroplast DNA from ancient rice seeds. Jpn. J. Breed. 41 (Sup. 1): 474-475.
Sato, Y.I., R. Ishikawa and H. Morishima 1990. Nonrandom association of genes and characters found in indica x japonica hybrids of rice. Heredity 65: 75-79.
Sato, Y.I. 1991. Variation in spikelet shape of the indica and japonica rice cultivars of Asian origin (Japanese/English). Jpn. J. Breed. 41: 121-134.
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