Mutant genes at the r and rb loci affect the structure and physico-chemical properties of pea seed starches
Mutant genes at the r and rb loci affect the structure and physico-chemical properties of pea seed starches
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DOI：
10.1093/jxb/46.12.1905
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发表时间：
1995-12-01
影响因子：
6.9
通讯作者：
Hedley, CL
中科院分区：
文献类型：
--
作者：
Bogracheva, TY;Davydova, NI;Hedley, CL
在两个位点，r和rb，已知编码基因的淀粉生物合成途径的突变基因，研究其对豌豆种子淀粉的结构和糊化的影响。比较来自四个系（RRRbRb，rrRbRb，RRrbrb，和rrrbrb）的淀粉，近等基因除了这两个位点的基因。所有淀粉的X射线衍射图谱均为C型，但A型和B型含量不同。在任一位点的突变的存在下增加了淀粉中的“B”多晶型物含量，尽管r突变的影响远大于r B。发现的rrRbRb淀粉的结晶结构的差异，这与高含量的无定形相，以及与支链淀粉结构的变化。此外，该样品的晶体结构的变化与淀粉在过量水中糊化期间缺乏合作转变相关。与野生型淀粉相比，RRrbrb淀粉在过量水中的糊化焓大大增加。有人提出，这种效果与特定的电荷之间的相互作用的淀粉颗粒中的分子。rrrbrb淀粉的晶体结构参数和糊化参数反映了两个基因的不同影响。在糊化方面，该淀粉具有较宽的协同转变和较低的转变焓和很高的转变高峰温度。
Mutant genes at two loci, r and rb, known to encode genes affecting the starch biosynthetic pathway, were studied for their effect on the structure and gelatinization of pea seed starches, Comparisons were made using starches from four lines (RRRbRb, rrRbRb, RRrbrb, and rrrbrb), near-isogenic except for genes at these two loci. All the starches had C-type X-ray diffraction patterns, but different contents of 'A' and 'B' polymorphs. The presence of a mutation at either locus increased the 'B' polymorph content in the starches, although the influence of the r mutation was much greater than that of rb. Differences were discovered in the crystalline stucture of the rrRbRb starch which correlated with a high content of amorphous phase as well as with the changes in amylopectin structure. In addition, changes in the crystalline structure of this sample correlated with a lack of co-operative transition during starch gelatinization in excess water. The RRrbrb starch had a greatly increased enthalpy of gelatinization in excess water compared with the wild-type starch. It is proposed that this effect is connected with specific charge interactions between the molecules in the starch granule. The rrrbrb starch had parameters of crystalline structure and gelatinization which reflected the different influences of the two genes, With regard to gelatinization, this starch had relatively wide co-operative transition and low enthalpy and a very high peak temperature of transition.