Mutant genes at therandrbloci affect the structure and physico-chemical properties of pea seed starches

Structural studies of starches with different water contents

“…It has been shown also that for starch from WT pea the shift for the first peak was similar to the peak shift observed for B-type potato starch and was related to the disruption of B-polymorphs. 17,23 The shift for the second peak was more similar to the peak shift observed for A-type maize starch and was related to the disruption of A-polymorphs. 17,23 A deconvolution procedure was applied to the bimodel patterns of the starches from WT and mutant peas in excess 0.6M KCl (Figure 5d).…”

“…The peak profiles of the crystalline parts from potato, maize, and wheat starches were determined as described in Bogracheva et al 22 As expected, the position of the peaks showed that the starches were of B-, A-, and A-type, respectively. It has been shown previously 17,22,23 that the crystalline parts of starches from WT pea, rug4-b, rb, rug3-a, and lam-a are composed from both A-and B-polymorphs, i.e., they are of C-type. In the current study similar analyses were carried out on starch from the lam-c mutant.…”

“…It was reported previously that gelatinization endotherms for starches from the WT and rb mutant are represented as bimodal curves. 17,23,24 Starches from the other three pea mutants (rug3-a, rug4-b, and lam-c) also have double peak endotherms in the salt solution conditions (Figure 5d). It has been shown also that for starch from WT pea the shift for the first peak was similar to the peak shift observed for B-type potato starch and was related to the disruption of B-polymorphs.…”

“…2,12,17,[22][23][24] This second type of transition is often attributed to mutants containing mutations affecting branching enzymes associated with amylopectin synthesis-for example, mutations at the r locus in pea (Pisum sativum) and the ae locus in maize (Zea mays). 2,19,22,23,25 It is also known that this type of gelatinization is characteristic for starches from peas containing a mutation at the rug5 locus, which is known to affect a starch synthase involved in amylopectin synthesis. 19,22 It can be suggested that the thermodynamic parameters of gelatinization transition are related to the structural characteristics of starch granules equilibrated in excess water.…”

“…14,17,[22][23][24]26 Data presented in these reports have shown that starch from WT peas is composed of complex granules in which B-polymorphs are at the centre and A-polymorphs at the periphery of all the granules. Also, x-ray diffraction was used to demonstrate variation for the proportion of A-and B-polymorphs in relatively dry starches from WT and some pea mutants.…”