dull: rice mutants with tissue-specific effects on the splicing of the waxy pre-mRNA
In the endosperm of japonica rice, du-1 and du-2 mutations cause the reduction of amylose contents. It was previously shown that the Wxb allele of rice, which is predominantly distributed in japonica rice, has a mutation in the 5′ splice site of intron 1 resulting in the creation of two weak 5′ splice sites within exon 1. In du-1 and du-2 mutants, spliced Wxb transcripts were highly reduced, whereas the processing of transcripts derived from three other genes highly expressed in endosperm was not apparently influenced. Results of competitive RT–PCR analysis indicate that transcripts spliced at the two newly created 5′ splice sites were equally affected in these two mutants. Genetic and molecular analyses of the effects of du-1 and du-2 on Wxa pre-mRNA with normal splice sites indicate that these two mutations do not affect the processing of Wxa pre-mRNA after splicing, suggesting that du-1 and du-2 are mutations of genes required for the efficient splicing of mutated Wxb pre-mRNA. Furthermore, du-1 and du-2 showed differential effects in endosperm and pollen. Although both mutations caused similar effects on the splicing of Wxb transcripts in endosperm, du-1 caused higher reduction of Wxb mRNA in pollen than in endosperm, while du-2 had a lesser effect in pollen than in endosperm. Based on these results, we propose that the du-1 and du-2 loci of rice encode tissue-specifically regulated splicing factors that are involved in alternative splicing of pre-mRNA in rice.
Document Type: Research Article
Affiliations: 1: Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan, 2: Yokohama Research Center, Mitsubishi Chemical Co., 1000 Kamoshida, Aoba-ku, Yokohama 227, Japan, and 3: Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka 812, Japan
Publication date: August 1, 2000