Theoretical and Applied Genetics

, Volume 101, Issue 3, pp 379–387 | Cite as

Geographic distribution and multilocus organization of isozyme variation of rice (Oryza sativa L.)

  • Z. Li
  • J. N. Rutger
Original Article

Abstract 

Genetic organization of isozyme variation in rice (Oryza sativa L.) was investigated based on 17 polymorphic isozyme loci using a sample of 511 accessions of worldwide origin. The genetic diversity within the species was very high (H=0.36 with 4.82 alleles per locus), as compared with most selfing plant species. Three diversity centers were detected for isozyme variation including South Asia, China and Southeast Asia. The accessions were classified into three well-differentiated cultivar groups corresponding to the indica and japonica subspecies, and a new unnamed group. Variation within the cultivar groups accounted for 80% of the total isozyme variation. Within-country variation accounted for 58% of the total variation while among-region and among-country variation within the cultivar groups accounted for only 14% and 8% of the total variation. Analyses using log-linear models revealed that pronounced non-random associations between and among alleles at many unlinked isozyme loci were organized in a non-hierarchical pattern, and subspecific and macro-geographic differentiation was much more pronounced in multilocus phenotype frequencies than in allelic frequencies at individual loci. These results suggest that selection on multilocus gene complexes was largely responsible for the maintenance of the extensive isozyme variation within the species and the indica-japonica differentiation. Our results further suggest the independent domestication of indica and japonica, the dual origins of the indica rice from China and South Asia (India), and the differentiation of the ecotypes ’javanica’ and the ’temperate japonica’ within the japonica subspecies.

Key words Rice Isozyme variation Multilocus organization Evolution 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Z. Li
    • 1
  • J. N. Rutger
    • 2
  1. 1.Department of Agronomy and Range Sciences, University of California and USDA-ARS, Davis, CA 95616, USA e-mail: zli@cgiar.org Present address: Z. Li, The International Rice Research Institute, P.O. Box 3127, 1271 Makati City, PhilippinesUS
  2. 2.National Rice Germplasm Evaluation and Enhancement Center, USDA-ARS, P.O. Box 287, Stuttgart, AR 72160, USAUS

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