10. Esterase isozymes in the wild rices of Guangxi, China

Genetic Resources Lab., Guangxi Academy of Agricultural Sciences Nanning, Guangxi. China.

A total of 848 accessions collected from various counties of Guangxi Zhoang Autonomous Region, including 355 of the common wild rice (O. sativa L.f. spontanea Roschev.), 406 native rice cultivars (O. sativa L., 265 Hsien and 146 Keng types) and 87 accessions of O. officinalis were examined with regard to esterase isozymes in dormant seed embryos by polyacrylamide-gel electrophoresis. The results were summarized as follows:

1. Altogether 41 different zymogram types were recognize. The genotypes commonly had bands 1A and 7A, of which the common wild rices and cultivars generally had bands 1A, 4A and 7A, and most of the former had 2A in addition. Most accessions of O. officinalis (79%) showed zymogram 1A, 5A and 7A, the rest showing zymogram 1A and 7A.

2. Cultivars showed 18 different zymograms. Of them, frequently found were 1A- 3A-4A-6A-7A-8A (26%), 1A-3A-4A-6A-7A (21%), and 1A-4A-7A (18%). Bands 3A and 6A were much more frequent in Hsien than in Keng types.

3.The common wild rices showed 29 different zymograms, but 54% of them had zymogram 1A-2A-4A-7A, which may be regarded as their fundamental zymogram.

4. The common wild rices were classified into three groups, typically wild, intermediate, and semi-wild (near domesticated) types by grain shedding, prostrate tillering, ratooning ability, non-synchronous flowering, fewer spikelets per panicle, long awns, and seed dormancy. Most of typically wild types (87%) had the fundamental zymogram 1A-2A-4A-7A. Its frequency was reduced to 39% in the intermediate and 12.5% in the semi-wild type. The frequency of band 2A was also reduced in the same order, while those of bands 3A and 6A increased with the change from truly wild to near-domesticated types.

5. The wild-rice populations growing in nearby rice fields showed more complex zymogram types than those in habitats distant from rice fields.