Elemental Imaging of Fertilized ZnO NP Wheat Endosperms Using Laser Ablation-Inductively Coupled Plasma Optical Emission Spectrometry

Zinc (Zn) is an essential trace element in the human body, and its deficiency can seriously affect health. Agronomic Zn biofortification with ZnO nanoparticles (ZnO NPs) in consumable wheat prospectively relieves Zn deficiency. We developed an elemental quantitative imaging laser ablation-inductively coupled plasma optical emission spectrometry method to examine the distributions of Zn and other micronutrient elements in wheat grain and the endosperm. After foliar application of ZnO NPs (four rounds), Zn content in the endosperm can be significantly increased (221 ± 61%), and the Zn, Ca, Mg, and P content gradient decreased from the outside seed coat and aleurone layer to the endosperm, whereas the Fe, Mn, K, Cu, Sr, and Ba content gradient decreased from the crease region to the deeper endosperm. This may indicate how different elements enter the endosperm. Foliar application of ZnO NPs did not change the micronutrient accumulation pattern but did change their contents in wheat grain.

Temperature and nitrogen supply interact to determine protein distribution gradients in the wheat grain endosperm

Gradients exist in the distribution of storage proteins in the wheat (Triticum aestivum) endosperm and determine the milling properties and protein recovery rate of the grain. A novel image analysis technique was developed to quantify both the gradients in protein concentration, and the size distribution of protein bodies within the endosperm of wheat plants grown under two different (20 or 28 °C) post-anthesis temperatures, and supplied with a nutrient solution with either high or low nitrogen content. Under all treatment combinations, protein concentration was greater in the endosperm cells closest to the aleurone layer and decreased towards the centre of the two lobes of the grain, i.e. a negative gradient. This was accompanied by a decrease in size of protein bodies from the outer to the inner endosperm layers in all but one of the treatments. Elevated post-anthesis temperature had the effect of increasing the magnitude of the negative gradients in both protein concentration and protein body size, whilst limiting nitrogen supply decreased the gradients.