Starch structure is often characterized by the chain-length distribution (CLD) of the linear molecules formed by breaking each branch-point. More information can be obtained by expanding into a second dimension: in the present case, the total undebranched-molecule size. This enables answers to questions unobtainable by considering only one variable. The questions considered here are: (i) are the events independent which control total size and CLD, and (ii) do ultra-long amylopectin (AP) chains exist (these chains cannot be distinguished from amylose chains using simple size separation). This was applied here to characterize the structures of one normal (RS01) wheat and two high-amylose (AM) mutant wheats (an SBEIIa knockout and an SBEIIa and SBEIIb knockout). Absolute ethanol was used to precipitate collected fractions, then size-exclusion chromatography for total molecular size and for the size of branches. The SBEIIa and SBEIIb mutations significantly increased AM and IC contents and chain length. The 2D plots indicated the presence of small but significant amounts of long-chain amylopectin, and the asymmetry of these plots shows that the corresponding mechanisms share some causal effects. These results could be used to develop plants producing improved starches, because different ranges of the chain-length distribution contribute independently to functional properties.

中文翻译：

---

从二维大分子​​结构洞察小麦淀粉生物合成

淀粉结构通常通过断裂每个支化点形成的线性分子的链长分布（CLD）来表征。通过扩展到第二个维度可以获得更多信息：在本例中，是未支链分子的总大小。这使得能够回答仅考虑一个变量无法获得的问题。这里考虑的问题是：(i) 控制总大小和 CLD 的事件是否独立，以及 (ii) 是否存在超长支链淀粉 (AP) 链（使用简单的大小分离无法将这些链与直链淀粉链区分开）。此处应用此来表征一种正常 (RS01) 小麦和两种高直链淀粉 (AM) 突变小麦（SBEIIa 敲除和 SBEIIa 和 SBEIIb 敲除）的结构。使用无水乙醇沉淀收集的级分，然后使用尺寸排阻色谱法测定总分子尺寸和支链尺寸。 SBEIIa和SBEIIb突变显着增加了AM和IC含量以及链长度。二维图表明存在少量但大量的长链支链淀粉，并且这些图的不对称性表明相应的机制具有一些因果效应。这些结果可用于开发生产改良淀粉的植物，因为不同范围的链长分布独立地影响功能特性。