Post-transcriptional regulation of the rice waxy gene
1996
Wang, Z.Y. | Zheng, F.Q. | Shen, G.Z. | Gao, J.P. | Snustad, D.P. | Li, M.G. | Zhang, J.L. | Hong, M.M.
Waxy (Wx) gene of rice encodes a granule-bound starch synthase required for synthesis of amylose in endosperm. As in other cereals, the amylose content of rice endosperm is thought to play important roles in grain yield, palatability, and processing quality. Therefore, we studied the genetic control of starch composition, a vital step in designing breeding and/or genetic engineering strategies aimed at enhancing both yield and eating quality. We used RNA gel blots to compare relative levels of steady-rate Wx transcripts in seeds of cultivars with different amylose content. We isolated and characterized a cDNA clone, designated cWx6, equivalent to the 3.3-kb Wx transcript, and the 5' and 3' termini of the cDNA insert on clone cWx6 were sequenced. Results confirm that the extra 1.1-kb segment present at the 5' terminus of the insert of clone cWx6 contains the 5' and 3' terminal sequences of intron 1 of rice Wx gene. Based on these, we hypothesize that the amylose content of rice endosperm is regulated at the level of Wx transcript processing, and, more specifically, at the stage of intron 1 excision from Wx pre-mRNA
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