Single kernel sampling method for maize starch analysis while maintaining kernel vitality

A nondestructive protocol for maize kernel starch sampling was developed, enabling starch preparation from a single kernel for analysis of starch structure while also maintaining the vitality of the seed. To develop the single kernel sampling (SKS) method, maize genotypes varying in starch structure including ae, wx, su2, du and normal in the W64A inbred line were used. Crude endosperm material was removed from the kernel crown, soaked, ground, washed, and dissolved in 90% DMSO. The sample represented ≈10% of the total kernel. Endosperm starch was also isolated from the same genotypes by a standard multikernel isolation (MKI) method. Starches isolated by the two methods were debranched and analyzed by high-performance size-exclusion chromatography (HPSEC) and fluorophore-assisted carbohydrate electrophoresis (FACE). HPSEC and FACE showed similar results for the two sampling methods for degree of polymerization (DP) ≤ 50. We concluded that the material obtained by SKS could be used for identifying amylopectin structural differences among genotypes. Kernel sampling for SKS had no effect on germination, thus plants could be grown for subsequent genetic crosses and analysis. The SKS method may be useful for the screening of populations of maize kernels from genotypes producing novel amylopectin structure, and allow the growth of novel genotypes for further analysis.