Comprehensive comparison and applications of different sections in investigating the microstructure and histochemistry of cereal kernels

This review summarizes the main applications of different sections and some improved sectioning methods in investigating the microstructure and histochemistry of cereal kernels. Thick sections of developing kernels prepared by free-hand and sliding microtome-aided sectioning method can be employed to elucidate tissue anatomy and histochemistry. The thin sections of mature kernels prepared by ultramicrotome-aided sectioning method can exhibit the micromorphology of starch granules when stained with iodine solution. The paraffin sections of developing kernels can exhibit the tissue anatomy of kernel, the accumulation of storage substances, and the location of protein and gene transcripts with immunohistochemistry and in situ hybridization techniques. The semithin resin sections can clearly exhibit the morphology of cells, starch granules, and protein bodies in kernel, but the sections prepared with different resins have various advantages and disadvantages for research investigating the morphology and histochemistry of cereal kernels. The improved methods of free-hand sectioning and ultramicrotome-aided sectioning of mature kernels are suitable for investigating the morphology of starch granules in a large number of samples in a short time. The modified method for preparing resin sections of whole kernels can be employed to determine the morphology and distribution of cells, starch granules, and storage protein in mature, developing, germinated, and cooked kernels in situ. This review could help researchers choose appropriate sections for investigating the microstructure and histochemistry of cereal kernels according to their study objectives.