Cereal grains inherently contain fewer proteins and minerals than some legumes. In spite of this, up to 75% of the daily caloric intake of people living in rural areas of the developing world comes from cereal-based foods with very low zinc (Zn) bioavailability and concentrations. In the biological system, Zn is commonly found bound to low molecular weight chelators (nicotianamine and phytochelatins) and their binding to proteins has been postulated but not exploited so far. Some reserve proteins known as ‘storage protein’ are highly abundant and could have a significant role not only for nutrition but as mineral deposition as well. However, most of the previous research work on Zn biofortification focused on proteins that are less abundant in the grain (i.e. transporters, chelators, etc. ), whereas very little research was done regarding the potential of the highly abundant ‘storage proteins’ (such as hordein in barley endosperm) to also serve as Zn binding proteins.

During his PhD studies, Nasir Uddin conducted a series of experiments using molecular and biochemical techniques within the transcriptomics and proteomics platform to increase the grain Zn content, and he suggested a way to improve protein quality/quantity of barley grain. He developed and applied Zn blotting assay to identify Zn binding proteins from barley grain. He also performed Zn-IMAC chromatography followed by protein identification with mass spectrometry to characterise the most abundant Zn binding proteins. In addition, he carried out Zn fertilisation experiments followed by quantitative real-time PCR for gene expression studies in developing barley grain to understand the influence of Zn on barley hordeins, nicotianamine synthase, yellow stripe-like transporters, catalase, glutathione-S-transferase, serpins and ?-amylase inhibitors, etc.

Nasir Uddin’s results suggest that some abundant barley storage proteins such as B-hordeins are capable of binding Zn or have a role in Zn storage. He also identified a set of genes/proteins among cupin and prolamin superfamilies, which might function as a Zn storage sink in the grain. In his PhD project, he also suggested a link between Zn concentration and redox stages of S-rich major storage protein of barley grain. Moreover, some of the methods developed in this project are novel and have never previously been applied in barley research. His key findings can therefore be useful for future Zn biofortification strategies as well as increasing the protein quality/quantity of cereal grains.

The PhD degree was completed at the Department of Molecular Biology and Genetics, Science and Technology, Aarhus University.

Time: Monday 24 March 2014 at 13.00
Place: Lecture Theatre, AU Flakkebjerg, Forsøgsvej 1, 4200 Slagelse
Title of dissertation: A new perspective of zinc storage and biofortification: Unraveling the role of zinc binding properties of barley
Contact information: Mohammad Nasir Uddin, MohammadNasir.Uddin@agrsci.dk, +45 3171 9261
Members of the assessment committee:
Professor Roger Reeves, Department of Chemistry, Massey University, New Zealand
Professor Jan K. Schjoerring, Department of Plant and Environmental Sciences, University of Copenhagen
Associate Professor Søren Borg (chair), Department of Molecular Biology and Genetics, Aarhus University
Main supervisor:
Associate Professor Eva Vincze, Department of Molecular Biology and Genetics, Aarhus University
Co-supervisor:
Dr Giuseppe Dionisio, Department of Molecular Biology and Genetics, Aarhus University
Language: The dissertation will be defended in English

The defence is public.
The dissertation is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1521, room 112, 8000 Aarhus C.