胚乳
突变体
蛋白质亚单位
胞浆
生物
生物化学
普通大麦
基因
淀粉
酶
植物
禾本科
作者
Philip E. Johnson,Nicola J. Patron,Andrew R. Bottrill,Jason R. Dinges,Brendan Fahy,Mary L. Parker,Darren N. Waite,Kay Denyer
出处
期刊:Plant Physiology
[Oxford University Press]
日期:2003-02-01
卷期号:131 (2): 684-696
被引量:108
摘要
Abstract To provide information on the roles of the different forms of ADP-glucose pyrophosphorylase (AGPase) in barley (Hordeum vulgare) endosperm and the nature of the genes encoding their subunits, a mutant of barley, Risø 16, lacking cytosolic AGPase activity in the endosperm was identified. The mutation specifically abolishes the small subunit of the cytosolic AGPase and is attributable to a large deletion within the coding region of a previously characterized small subunit gene that we have called Hv.AGP.S.1. The plastidial AGPase activity in the mutant is unaffected. This shows that the cytosolic and plastidial small subunits of AGPase are encoded by separate genes. We purified the plastidial AGPase protein and, using amino acid sequence information, we identified the novel small subunit gene that encodes this protein. Studies of the Risø 16 mutant revealed the following. First, the reduced starch content of the mutant showed that a cytosolic AGPase is required to achieve the normal rate of starch synthesis. Second, the mutant makes both A- and B-type starch granules, showing that the cytosolic AGPase is not necessary for the synthesis of these two granule types. Third, analysis of the phylogenetic relationships between the various small subunit proteins both within and between species, suggest that the cytosolic AGPase single small subunit gene probably evolved from a leaf single small subunit gene.
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