EVOLUTION IN THE GENE REGULATION OF THE RICE Wx GENE

The rice wx locus has two functional alleles, Wx^a and Wx^b . Wx^a allele produces about 10-fold higher levels of mRNA and protein than Wx^b does. Evolutionary studies indicate Wx^b is derived from Wx^a during domestication of Japonica type of rice. What kinds of mutations caused such a large change...

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Bibliographic Details
Published inGenes & Genetic Systems Vol. 71; no. 6; p. 429
Main Authors HIRANO Hiro-Yuki, EIGUCHI Mitsugu, SANO Yoshio
Format Journal Article
LanguageJapanese
Published The Genetics Society of Japan 1996
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Summary:The rice wx locus has two functional alleles, Wx^a and Wx^b . Wx^a allele produces about 10-fold higher levels of mRNA and protein than Wx^b does. Evolutionary studies indicate Wx^b is derived from Wx^a during domestication of Japonica type of rice. What kinds of mutations caused such a large change in the expression level of the Wx gene during the relatively short period of the evolution? The rice Wx gene has a long intron at the upstream of ATG codon. Northern blot analysis showed Wx^b produced a larger band including the first intron in addition to the mature transcript, although no such band was detected in the transcript from Wx^a allele. The function of the DNA sequence that includes the promoter region and the first intron was analyzed by transient assay system. Together with the comparison of DNA sequence of various cultivated and wild rice, we revealed that the sequence difference responsible for the expression level between Wx^a and Wx^b is 1-bp change in the splice donor site of the first intron. It seems likely in rice with Wx^b that the low efficiency of splicing and accumulation of abnormal transcript causes the lower rate of transcription and/or that quick degradation of abnormal transcript results in a reduced level of the mature transcript.
ISSN:1341-7568