Structural variability between starch granules in wild type and in ae high-amylose mutant maize kernels

Abstract

Starch granule structure within wild-type and ae high-amylose mutant maize kernels has been mapped in situ using light, electron and atomic force microscopy, and both Raman and infra-red spectroscopy. The population of wild-type starch granules is found to be homogenous. The ae mutant granule population is heterogeneous. Heterogeneity in chemical and physical structure is observed within individual granules, between granules within cells, and spatially within the kernel. The highest level of heterogeneity is observed in the region where starch is first deposited during kernel development. Light microscopy demonstrates structural diversity through use of potassium iodide/iodine staining and polarised microscopy. Electron and atomic force microscopy, and infra-red and Raman spectroscopy defined the nature of the structural changes within granules. The methodology provides novel information on the changes in starch structure resulting from kernel development.

Keywords: Atomic force microscopy; Electron microscopy; High-amylose maize; Infra-red spectroscopy; Kernel structure; Light microscopy; Raman spectroscopy; ae maize.