The challenges and opportunities associated with biofortification of pearl millet (Pennisetum glaucum) with elevated levels of grain iron and zinc Hanna R. Manwaring1, Frances Bligh2, Rattan Yadav1* 1
IBERS, Aberystwyth University, United Kingdom, 2R&D, Unilever, United Kingdom
Submitted to Journal: Frontiers in Plant Science
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Specialty Section: Plant Nutrition Article type: Review Article
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Manuscript ID: 237292 Received on: 17 Oct 2016 Revised on: 24 Nov 2016
Frontiers website link: www.frontiersin.org
Conflict of interest statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
Author contribution statement HM - Author of the manuscript, wrote and designed manuscript, implemented and revised during this process. RSY - participated in revising it critically for important intellectual content. FB - participated in revising it critically for important intellectual content.
Keywords nutrition, biofortification, plant breeding, genetic improvement, pearl millet
Abstract Word count:
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Deficiencies of essential micronutrients such as iron and zinc are the cause of extensive health problems in developing countries. They adversely affect performance, productivity and are a major hindrance to economic development. Since many people who suffer from micronutrient deficiencies are dependent on staple crops to meet their dietary requirements, the development of crop cultivars with increased levels of micronutrients in their edible parts is becoming increasingly recognised as a sustainable solution. This is largely facilitated by genetics and genomic platforms. The cereal crop pearl millet (Pennisetum glaucum), is an excellent candidate for genetic improvement due to its ability to thrive in dry, semi-arid regions, where farming conditions are often unfavourable. Not only does pearl millet grow in areas where other crops such as maize and wheat do not survive, it contains naturally high levels of micronutrients, proteins and a myriad of other health benefitting characteristics. This review discusses the current status of iron and zinc deficiencies and reasons why interventions such as fortification, supplementation and soil management are neither practicable nor affordable in poverty stricken areas. We argue that the most cost effective, sustainable intervention strategy is to biofortify pearl millet with enhanced levels of bioavailable iron and zinc. We discuss how naturally occurring genetic variations present in germplasm collections can be incorporated into elite, micronutrient rich varieties and what platforms are available to drive this research. We also consider the logistics of transgenic methods that could facilitate the improvement of the pearl millet gene pool.
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Funding statement Acknowledgement: Authors are grateful to BBSRC and Unilever for iCASE PhD studentship award via grant number BB/M502728/1.
Hanna Manwaring, Aberystwyth University, 100720668
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The challenges and opportunities associated with biofortification of pearl millet (Pennisetum glaucum) with elevated levels of grain iron and zinc Hanna Rose Manwaring 1*, H. Frances J. Bligh2 and Rattan Yadav 1
1. IBERS, Gogerddan, Aberystwyth University, SY23 3EB, UK 2. Unilever R and D, Colworth Science Park, Sharnbrook, MK44 1LQ, UK Correspondence: *Corresponding Author: Rattan Yadav
[email protected] Word count: 9200 words.
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No. of figures/tables: 4
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Abstract:
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Deficiencies of essential micronutrients such as iron and zinc are the cause of extensive
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health problems in developing countries. They adversely affect performance, productivity and
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are a major hindrance to economic development. Since many people who suffer from
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micronutrient deficiencies are dependent on staple crops to meet their dietary requirements,
16
the development of crop cultivars with increased levels of micronutrients in their edible parts
17
is becoming increasingly recognised as a sustainable solution. This is largely facilitated by
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genetics and genomic platforms. The cereal crop pearl millet (Pennisetum glaucum), is an
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excellent candidate for genetic improvement due to its ability to thrive in dry, semi-arid
20
regions, where farming conditions are often unfavourable. Not only does pearl millet grow in
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areas where other crops such as maize and wheat do not survive, it contains naturally high
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levels of micronutrients, proteins and a myriad of other health benefitting characteristics.
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This review discusses the current status of iron and zinc deficiencies and reasons why
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interventions such as fortification, supplementation and soil management are neither
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practicable nor affordable in poverty stricken areas. We argue that the most cost effective,
26
sustainable intervention strategy is to biofortify pearl millet with enhanced levels of
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bioavailable iron and zinc. We discuss how naturally occurring genetic variations present in
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germplasm collections can be incorporated into elite, micronutrient rich varieties and what
29
platforms are available to drive this research. We also consider the logistics of transgenic
30
methods that could facilitate the improvement of the pearl millet gene pool.
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Key words:
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Hanna Manwaring, Aberystwyth University, 100720668 32
Nutrition, Pearl Millet, Biofortification, Plant Breeding, Genetic Improvement
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The consequences of micronutrient deficiencies (iron and zinc)
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On a global scale, over three billion people suffer from micronutrient deficiencies (MNDs) of
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essential minerals and vitamins (Chasapis et al., 2012). Deficiencies in iron (Fe) and zinc
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(Zn) are two of the most common and widespread MNDs (Bailey et al., 2015). This is
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expensive to society as the consequences include: poor health, increased mortality, low work
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productivity, learning disabilities in children and poor national economic development at the
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country level (Welch & Graham, 2004). At an individual level, children require up to 10mg
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of Fe and Zn per day (8mg for adults). This amount is essential to sustain life and to ensure
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optimal physiological function (Bailey et al., 2015, Halliwell, 1996, Prasad, 2008). Target
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levels of Fe and Zn required for efficient function of the human body can be seen in Table 1.
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In developing countries within Africa and Asia, the intake of flesh foods, which are abundant
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in readily available haem Fe and Zn is at best limited due to economic, cultural, or religious
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constraints. Instead, staple diets are primarily plant based (Gibson et al., 2000). Non haem Fe
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and Zn are obtained from a large number of plant based food items such as dark leafy
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vegetables, brown rice, beans, nuts and seeds. These are more available generally and are the
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source of most Fe and Zn in the diet world-wide. People living in poverty stricken areas have
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limited access to even these foods. Instead, they largely depend on grain from staple crops,
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which they eat on a daily basis.
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Fe deficiency is the most common MND worldwide and can lead to microcytic anaemia,
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impaired immune function and poor endocrine function (Bailey et al., 2015). According to
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the World Health Organisation (WHO, 2016) over 30% of the global population suffer from
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anaemia due to Fe deficiency; this mostly affects women and children in resource poor areas
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(Halliwell, 1996). Young children, pregnant and postpartum women are considered to be
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most at risk due to the high Fe demands associated with infant growth and pregnancy
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(Stoltzfus et al., 2004). Severe Fe deficiency is associated with increased maternal mortality
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and can increase the rate of premature delivery and miscarriage (Carriaga et al., 1991). Fe
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deficiency also contributes substantially to maternal deaths from dystocia (obstructed labour)
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and is associated with low offspring birth weight (less than 2,500g). These deficits lead to
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poor health and low productivity in adulthood as the detrimental effects in childhood persist
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to adulthood.
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Hanna Manwaring, Aberystwyth University, 100720668 63
Adequate Zn is required for efficient immune function, and deficiency is associated with
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increased incidence of diarrhoeal diseases and acute respiratory infections, which are major
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causes of infant mortality (Bailey et al., 2015, Hambridge, 2000, Black, 2003). Zn deficiency
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is most prevalent in Africa and South-East Asia (Caulfield & Black, 2004) and many studies
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have demonstrated a relationship between low plasma Zn levels during pregnancy and low
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birth weight (
