Changes in the starch-protein interface depending on common wheat grain hardness revealed using atomic force
Emna Chichti1, Matthieu George2, Jean-Yves Delenne1
1INRA, UMR 1208, Ingénierie des Agropolymères et Technologies Emergentes, 2 Place Viala, 34060 Montpellier Cedex 02, France.
Plant Science : an International Journal of Experimental Plant Biology
|September 24, 2015
Summary
Wheat hardness, determined by puroindoline b gene, affects starch and protein interactions. Soft wheat shows a lipid-lubricated interface, unlike hard wheat, revealing nano-mechanical differences in grain endosperm.
Area of Science:
- Plant Biology
- Materials Science
- Agricultural Science
Background:
- Wheat grain hardness is a crucial quality trait, primarily influenced by the puroindoline b gene.
- Understanding the nano-mechanical properties of the wheat endosperm, specifically the starch-protein interface, is key to explaining grain texture differences.
Purpose of the Study:
- To investigate the in situ nano-mechanical differences at the starch-protein interface in wheat endosperm.
- To correlate these differences with the allelic status of the puroindoline b gene and its impact on grain hardness.
Main Methods:
- Utilized atomic force microscope (AFM) tip to progressively abrade non-cut starch granules within the endosperm protein matrix of wheat grain sections.
- Analyzed abrasion profiles of starch granules from near-isogenic wheat lines differing in the puroindoline b gene (hard vs. soft).
Main Results:
- Hard wheat lines exhibited two distinct abrasion profiles: one on the protein layer and one on the starch granule.
- Soft wheat lines displayed an additional profile with a marked stop at the protein-starch transition, suggesting a lubricant role for lipids.
- This lubricating effect in soft wheat was linked to the presence of wild-type puroindolines, potentially interacting with polar lipids.
Conclusions:
- This study provides the first in situ evidence of nano-mechanical differences at the starch-protein interface in wheat endosperm based on puroindoline allelic status.
- The findings highlight the role of puroindolines and associated lipids in modulating the mechanical properties of the wheat grain, contributing to texture differences.
