Plant metallothioneins as potential players in food security

One of the most important challenges nowadays, in the face of a growing world population, is complex issue of food security that is defined as the availability of sufficient amount of nutritious food for everybody, produced in sustainable way. There are numerous factors threating food security including declines in water supplies and more often and more severe drought events. On the other hand 2 billion people worldwide suffer from “hidden hunger” caused by micronutrient deficiency that leads to serious health problems. Among multiple micronutrients that are essential for all life, the importance of zinc has recently come to the fore. Zinc is involved in almost every metabolic process and thus, the effects of zinc deficiency are serious and multifactorial. WHO estimates that deficiency of only this single micronutrient leads to the death of almost 0.5 million children every year. Cereals including wheat, barley, maize, rice, rye, oats and sorghum are important source of food worldwide but the bioavailability of zinc (and also iron) from gains is very limited. In developing countries where diversification of diet (more fish and meat) is rather unrealistic efforts are needed to improve the content/bioavailability of zinc in staple plants. Long-term and cost-effective biofortification strategies should base on improvement of plant cultivars rather than on application of trace elements into soil. In order to achieve this the mechanisms underlying micronutrients transport, accumulation and storage needs to be thoroughly understood.

The aim of my project is to evaluate o role of metallothioneins (MTs) in zinc accumulation in edible parts of plants and in drought stress tolerance. In my work I concentrate on Sorghum bicolor (great millet), a crop with remarkable drought resistance. Sorghum is widely grown in arid and semi-arid region of Africa where is a major dietary staple for more than 500 million people. It is also widely grown in Asia, America and the Indian subcontinent for its fibre, fuel and ethanol production. In addition, sorghum is an attractive candidate for biofortification purpose because it is widely cultivated in regions of the world where micronutrients malnutrition is the most severe. During my project I would like to answer the questions: (i) whether sorghum MTs are involved in drought tolerance and possibly other abiotic stress tolerance and (ii) whether sorghum MTs are involved in zinc accumulation and discrimination between essential zinc and highly toxic cadmium. To address these question a unique cross-disciplinary approach will be used. The knowledge generated in my project offers the promise to enable the development of crop plant cultivars which will combine high yield, obtained even in adverse environmental conditions, with high nutritional value.

1. The expression of sorghum MTs (SbMTs) will be analysed in sorghum organs (root, steam, leaf, flower) and during seed development and germination utilising quantitative real-time PCR.

2. To analyse metal specificities and structural features of sorghum MTs they will be recombinantly expressed in E. coli in the presence of zinc, cadmium, and copper and purified by fast performance liquid chromatography (FPLC). Analysis by inductively-coupled-plasma optical emission spectroscopy (ICP-OES) and native electrospray ionisation mass spectrometry (ESI-MS) will provide identity and quality of bound metal ions. The impact of metal binding on protein folding will be monitored by 2D and 3D (¹H, ¹⁵N, ¹³C, ¹¹¹Cd) NMR spectroscopy.

3. Sorghum plants will be grown in soil containing different amounts of cadmium and inductively-coupled-plasma mass spectrometry (ICP-MS) will be used to analyse the mental content in different plant organs but especially in seeds.

4. In order to evaluate the role of sorghum MTs in drought stress tolerance transgenic Arabidopsis with ectopic expression of SbMTs will be created. In addition oxidative stress tolerance of transgenic plants will be evaluated. MTs will be also evaluated in vitro with respect to their antioxidant and ROS-scavenging potency by analysing the potential of fully and partially metallated complexes for protecting DNA against oxidative damage in vitro.

Marie Sklodowska-Curie Individual Fellowship conducted within the Horizon 2020 programme

(Grant No. 701492-PMTFOS).

https://horizon-magazine.eu/article/boosting-nutrients-crops-beat-hidden-hunger-poor-diet.html

EDUCATION

October 2007- October 2013

Nicolaus Copernicus University in Toruń

Faculty of Biology and Environmental Protection

Department of Genetics

PhD in Molecular Biology

PhD thesis: Molecular and functional characteristics of Brassica napus metallothionein genes

October 2005 – July 2007

Nicolaus Copernicus University in Toruń

Faculty of Biology and Earth Science

Master of Science (M.Sc.) in Biotechnology

Master thesis: The analysis of expression of Ipomoea nil aquaporin gene PnPIP1 in response to abiotic stress conditions

October 2002 – 2005 July

Nicolaus Copernicus University in Toruń

Faculty of Biology and Earth Science

Bachelor of Science (B.Sc.) in Biotechnology

Bachelor thesis: The analysis of expression of genes involved in oxidative stress tolerance in plants

EMPLOYMENT

October 2012 – present

Research and Teaching Fellow

Department of Genetics, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Toruń, Poland

August 2017 – present

Marie Curie Research Fellow

Department of Chemistry, University of Warwick, Coventry, UK

PUBLICATIONS

Mierek-Adamska A, Dąbrowska G, Goc A (2009) Genetically modified plants and strategies of soil remediation from heavy metals. Advances in Cell Biology 36: 649 – 662 (article in Polish, abstract in English).

Dąbrowska G, Hrynkiewicz K, Kłosowska K, Trejgell A, Mierek-Adamska A (2010) The effect of rhizobacteria on germination of Brassica napus L. seeds in the presence of heavy metals (Cd, Cu, Pb, Zn). Oilseed Crops XXXI: 85 – 97 (article in Polish, abstract in English).

Dąbrowska G, Mierek-Adamska A, Goc A (2012) Plant metallothioneins: putative functions identified by promoter analysis in silico. ABC Series Botanica 54/2: 109-120.

Dąbrowska G, Hrynkiewicz K, Mierek-Adamska A, Goc A (2012) The sensitivity of spring and winter varieties of oilseed rape to heavy metals and rhizobacteria. Oilseed Crops XXXIII: 201 – 220 (article in Polish, abstract in English).

Dąbrowska G, Mierek-Adamska A, Goc A (2013) Characterisation of Brassica napus L. metallothionein genes (BnMTs) expression in organs and during seed germination. Australian Journal of Crop Science 7: 1324 – 1332.

Ostrowski M, Mierek-Adamska A, Porowińska D, Goc A, Jakubowska A (2016) Cloning and characterization of indole-3-acetic amino acid synthetase PsGH3 from pea. Plant Physiology and Biochemistry 107: 9-20.

Mierek-Adamska A, Tylman-Mojżeszek W, Znajewska Z, Dąbrowska G (2017) Bacterial metallothioneins. Advances in Microbiology 56: 171-179 (article in Polish, abstract in English).

M'kandawire E, Mierek-Adamska A, Stürzenbaum SR, Choongo K, Yabe J, Mwase M, Saasa N, Blindauer CA (2017) Metallothionein from wild populations of the African catfish Clarias gariepinus: from sequence, protein expression and metal binding properties to transcriptional biomarker of metal pollution. International Journal of Molecular Sciences 18: 1548.

Mierek-Adamska A, Znajewska Z, Goc A, Dąbrowska G (2018) Molecular cloning and characterisation of Ipomoea nil metallothioneins. Turkish Journal of Botany 42: 247-256.

Mierek-Adamska A, Dąbrowska G, Blindauer CA (2018) The type 4 metallothionein from Brassica napus seeds folds in a metal-dependent fashion and favours zinc over other metals. Metallomics 10: 1430-1443.

Dr Agnieszka Mierek-Adamska

Marie Curie Research Fellow

B600, Department of Chemistry

University of Warwick

A.Mierek-Adamska.1@warwick.ac.uk