Chen.Ji@jic.ac.uk

Wheat (Triticum aestivum) grain filling is coordinated with cell expansion that significantly enlarges the grain size. This stage represents the peak period for nutrient and micronutrient transportation within the grains. Wheat grain has low levels of iron and zinc which contributes to micronutrient deficiencies in the billions of people who rely on wheat as a staple food. Due to technical limitations, many genes involved in micronutrient processes and their related mechanisms are yet to be discovered. Through understanding the transport processes, we aim to increase the levels of iron and zinc in wheat grains, to benefit human health.

In this study, we combined phenomics and transcriptomics to observe cell expansion, endosperm filling and micronutrient content in wheat cultivar Cadenza 12 days and 18 days after flowering. By leveraging XRF (X-ray Fluorescence Spectroscopy), ICP-OES (Inductively coupled plasma - optical emission spectrometry), Stereo-seq spatial transcriptomics and single-nucleus analysis, we delineated the regulatory networks and key transcription factors involved in the development of grains and the transport of Zn/Fe, with confirmation currently in progress through targeted in-situ analyses techniques.

We identified clusters specific to various tissue components and transporters that are specifically expressed in the embryo-adjacent endosperm and starchy endosperm, which we hypothesise are involved in the transport of micronutrients.

These findings offer a strategy for exploring gene regulatory networks at the single-cell level in wheat grains and provide insights into improving wheat grain micronutrient content.