Metabolic Biology, John Innes Centre, Colney, Norwich, United Kingdom.
Plant Physiol. 2010 Oct;154(2):643-55. doi: 10.1104/pp.110.161844. Epub 2010 Aug 10.
The metabolism of starch is of central importance for many aspects of plant growth and development. Information on leaf starch metabolism other than in Arabidopsis (Arabidopsis thaliana) is scarce. Furthermore, its importance in several agronomically important traits exemplified by legumes remains to be investigated. To address this issue, we have provided detailed information on the genes involved in starch metabolism in Lotus japonicus and have characterized a comprehensive collection of forward and TILLING (for Targeting Induced Local Lesions IN Genomes) reverse genetics mutants affecting five enzymes of starch synthesis and two enzymes of starch degradation. The mutants provide new insights into the structure-function relationships of ADP-glucose pyrophosphorylase and glucan, water dikinase1 in particular. Analyses of the mutant phenotypes indicate that the pathways of leaf starch metabolism in L. japonicus and Arabidopsis are largely conserved. However, the importance of these pathways for plant growth and development differs substantially between the two species. Whereas essentially starchless Arabidopsis plants lacking plastidial phosphoglucomutase grow slowly relative to wild-type plants, the equivalent mutant of L. japonicus grows normally even in a 12-h photoperiod. In contrast, the loss of GLUCAN, WATER DIKINASE1, required for starch degradation, has a far greater effect on plant growth and fertility in L. japonicus than in Arabidopsis. Moreover, we have also identified several mutants likely to be affected in new components or regulators of the pathways of starch metabolism. This suite of mutants provides a substantial new resource for further investigations of the partitioning of carbon and its importance for symbiotic nitrogen fixation, legume seed development, and perenniality and vegetative regrowth.
淀粉的代谢对植物生长和发育的许多方面都至关重要。除拟南芥（Arabidopsis thaliana）外，关于叶片淀粉代谢的信息很少。此外，其在几个农艺重要性状中的重要性，如豆科植物，仍有待研究。为了解决这个问题，我们提供了关于豌豆（Lotus japonicus）淀粉代谢相关基因的详细信息，并对影响淀粉合成的五个酶和两个淀粉降解酶的正向和 TILLING（靶向诱导基因组局部缺失）反向遗传突变体进行了全面的鉴定。这些突变体为 ADP-葡萄糖焦磷酸化酶和葡聚糖，特别是水二激酶 1 的结构-功能关系提供了新的见解。突变体表型分析表明，豌豆和拟南芥叶片淀粉代谢途径在很大程度上是保守的。然而，这些途径对植物生长和发育的重要性在两个物种之间有很大的不同。由于缺乏质体磷酸葡萄糖变位酶的基本上不含淀粉的拟南芥植物相对于野生型植物生长缓慢，而豌豆的等效突变体即使在 12 小时的光周期下也能正常生长。相比之下，淀粉降解所需的 GLUCAN，WATER DIKINASE1 的缺失对豌豆的生长和繁殖力的影响比拟南芥大得多。此外，我们还鉴定了几个可能在淀粉代谢途径的新组分或调节剂中受到影响的突变体。这套突变体为进一步研究碳的分配及其对共生固氮、豆科种子发育、多年生和营养再生的重要性提供了一个重要的新资源。
