The alk locus controls amylopectin structure and starch synthase activity in rice
2003
Umemoto, T. | Yano, M. | Satoh, H. | Shomura, A. | Okamoto, K. | Kobayashi, K. | Nakamura, Y.
The acl(t) gene, which controls the chain-length distribution of amylopectin in endosperm starch of rice, was mapped on chromosome 6 by analyzing backcross inbred lines derived from a cross between a japonica variety (Nipponbare) and an indica variety (Kasalath). The mapped position was at the same locus as the alk gene, which is known to be responsible for varietal differences in the disintegration property of endosperm starch of rice in an alkali (KOH) solution. Zymogram analyses for starch-metabolizing enzymes apparently revealed that one of the starch synthase activities was also regulated by the alk locus. The chain-length distribution of amylopectin was similar to that of Kasalath when the starch synthase activity was present, and similar to that of Nipponbare, which is rich in short chains, when the activity was lacking. In addition, a rice EST clone that shows high sequence similarity with the maize starch synthase lla gene was also mapped at the alk locus. These results suggested that the alk gene, acl(t) gene, and the gene that controls the starch synthase activity mapped at the alk locus may be identical. It is possible that the alkali disintegration property of rice endosperm is regulated by starch synthase activity via the structural alteration of amylopectin.
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