EVIDENCE FOR INDEPENDENT GENETIC-CONTROL OF THE MULTIPLE FORMS OF MAIZE ENDOSPERM BRANCHING ENZYMES AND STARCH SYNTHASES
EVIDENCE FOR INDEPENDENT GENETIC-CONTROL OF THE MULTIPLE FORMS OF MAIZE ENDOSPERM BRANCHING ENZYMES AND STARCH SYNTHASES
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DOI：
10.1104/pp.67.6.1141
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发表时间：
1981-01-01
期刊：
影响因子：
7.4
通讯作者：
PREISS, J
中科院分区：
文献类型：
--
作者：
BOYER, CD;PREISS, J
对4个玉米品种籽粒提取液中的可溶性淀粉合成酶和淀粉分支酶进行了比较。正常(非突变)玉米提取物中含有2种淀粉合成酶和3种分支酶。在不同的测定条件下，通过层析性质和动力学性质可以区分不同的组分。隐性直链淀粉延伸器(Ae)等位基因纯合的籽粒缺少分支酶IIb。柠檬酸刺激的淀粉合成酶I活性降低。这种活性可以通过在该组分中添加分支酶来再生。其他淀粉合成酶组分均与正常酶组分不同。隐性迟钝(Du)等位基因纯合的籽粒提取物含有较低的分支酶IIa和淀粉合成酶II活性。其他组分与正常酶组分无差异。对双突变体ae Du的籽粒提取物的分析表明，这2个突变体是独立作用的。没有分支酶IIb，淀粉合成酶I的柠檬酸刺激反应减少，但可以通过添加分支酶再生(ae属性)，分支酶IIa和淀粉合成酶II都大大降低(Du属性)。玉米胚乳和杜氏胚乳的直链淀粉含量分别为66%和42%，高于正常胚乳的26%。此外，ae淀粉中的支链淀粉组分比普通或Du淀粉中的支链淀粉分枝程度要低。上述观察结果表明，淀粉的变化可能是由于可溶性合酶和分支酶的变化所致。
Soluble starch synthase and starch-branching enzymes in extracts from kernels of 4 maize genotypes were compared. Extracts from normal (nonmutant) maize contained 2 starch synthases and 3 branching enzyme fractions. The different fractions could be distinguished by chromatographic properties and kinetic properties under various assay conditions. Kernels homozygous for the recessive amylose-extender (ae) allele were missing branching enzyme IIb. The citrate-stimulated activity of starch synthase I was reduced. This activity could be regenerated by the addition of branching enzyme to this fraction. No other starch synthase fractions were different from normal enzymes. Extracts from kernels homozygous for the recessive dull (du) allele contained lower branching enzyme IIa and starch synthase II activities. Other fractions were not different from the normal enzymes. Analysis of extracts from kernels of the double mutant ae du indicated that the 2 mutants act independently. Branching enzyme IIb was absent and the citrate-stimulated reaction of starch synthase I was reduced but could be regenerated by the addition of branching enzyme (ae properties) and both branching enzyme IIa and starch synthase II were greatly reduced (du properties). Starch from ae and du endosperms contains higher amylose (66 and 42%, respectively) than normal endosperm (26%). In addition, the amylopectin fraction of ae starch is less highly branched than amylopectin from normal or du starch. The above observations suggest that the alterations of the starch may be accounted for by changes in the soluble synthase and branching enzyme fractions.