Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1991 Apr;95(4):1181-8. doi: 10.1104/pp.95.4.1181.
Mutants of Arabidopsis thaliana (L.) Heynh. with altered regulation of starch degradation were identified by screening for plants that retained high levels of leaf starch after a period of extended darkness. The mutant phenotype was also expressed in seeds, flowers, and roots, indicating that the same pathway of starch degradation is used in these tissues. In many respects, the physiological consequences of the mutations were equivalent to the effects observed in previously characterized mutants of Arabidopsis that are unable to synthesize starch. One mutant line, which was characterized in detail, had normal levels of activity of the starch degradative enzymes alpha-amylase, beta-amylase, phosphorylase, D-enzyme, and debranching enzyme. Thus, it was not possible to establish a biochemical basis for the phenotype, which was due to a recessive mutation at a locus designated sex1 at position 12.2 on chromosome 1. This raises the possibility that hitherto unidentified factors, altered by the mutation, play a key role in regulating or catalyzing starch degradation.
通过筛选在延长的黑暗期后仍能保持高水平叶淀粉的植物，鉴定出拟南芥（L.）Heynh.中淀粉降解调控改变的突变体。该突变体表型也在种子、花和根中表达，表明这些组织中使用了相同的淀粉降解途径。在许多方面，突变的生理后果与先前表征的无法合成淀粉的拟南芥突变体观察到的效果相当。一个被详细表征的突变体系具有正常水平的淀粉降解酶α-淀粉酶、β-淀粉酶、磷酸化酶、D-酶和分支酶活性。因此，不可能为该表型建立生化基础，该表型是由于位于染色体 1 上位置 12.2 的 sex1 位点的隐性突变引起的。这提出了一种可能性，即突变改变的 hitherto 未被识别的因素在调节或催化淀粉降解中发挥关键作用。
