National Institute of Aerobiological Resources, Tsukuba, 305 Japan
Esterase variations of Asian rice cultivars are determined by genes at 4
loci, Est-1, Est-2, Est-3 (Nakagahra 1977), and Est-4 (Unpublished). Alleles
so far found are 2 at Est-1 (Est-1 and Est-1nul), 3 at Est-2 (Est-2S,
Est-2F, and Est-2nul) , 2 at Est-3 (Est-3S and Est-3F), and 3 at Est-4
(Est-4S, Est-4F, and Est-4nul). Est-2 is located on Chromosome 7 (1st Linkage
group) with the following gene sequence and linkage intensities (Nakagahra
and Hayashi 1976).
There was no evidence for linkage between Est-1 and Est-2 or between Est-2
and Est-3 (Nakagahra 1977). The geographical distribution of genotypes for
these enzymes was reported earlier with 1,190 indigenous rice cultivars
(Nakagahra 1978). Since then, the present author and coworkers have explored
different regions of Asia to obtain more material, and have studied a total
of 2,752 native varieties.
With regard to the Est-1, Est-2, and Est-3 loci, 12 genotypes were found
as follows:
Est-1 Est-2 Est-3 Est-I Est-2 Est-3 1 1 2S 3F 7 nul 2S 3F 2 1 2S 3S 8 nul 2S 3S 3 1 2F 3F 9 nul 2F 3F 4 1 2F 3S 10 nul 2F 3S 5 1 nul 3F 11 nul nul 3F 6 1 nul 3S 12 nul nul 3S
Fig. 1. Geographic distribution of esterase genotypes in native reice varieties in Asia.
References
Nakagahra, M. and K. Hayashi 1976. Detection of esterase isozyme loci of Oryza sativa L. Jpn. J. Breed 26 Suppl. 1: 114-115 (in Japanese).
-----, 1977. Genic analysis for esterase isoenzymes in rice cultivars. Jpn. J. Breed. 27: 141-148.
-----, 1978. The differentiation, classification and center of genetic diversity of cultivated rice by isozyme analysis. Trop. Agric. Res. Ser. 11: 77-82.