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Nutritional enhancement of fruits and vegetables


   School of Biological Sciences


About the Project

Background. A wealth of scientific evidence now exists to show that diets rich in fruits and vegetables are beneficial to human well-being and health [1]. The ageing European population and increased incidence of dietary-related pathologies in children also provide a pertinent economic incentive for improved diets [2]. As a consequence of these social and economic factors, most western governments now recommend a daily intake of at least five portions of fruit and vegetables [3] and recently the EAT Lancet Commission advocates a diet rich in plant-based foods confers both improved health and environmental benefits [4]. The beneficial effects of fruits and vegetables have been attributed to the presence of various phytochemicals, such as carotenoids, tocopherols, and polyphenols (e.g. flavonaoids), [5].  

During the 1990’s metabolic engineering approaches were used extensively to enhance specific steps within biochemical pathways to increase the content of health-related compounds. For example, lycopene and β-carotene content has been elevated in ripe tomato fruit by overexpressing carotenoid biosynthetic enzymes [6 & 7]. The formation of flavonoids in tomato fruit has also been enhanced through the over-expression of transcription factors to facilitate co-ordinated expression throughout the pathway [8]. Similar regulators have also facilitated the simultaneous elevation of multiple classes of health-related compounds [9]. Although GM approaches have been shown to deliver potentially beneficial traits for human well-being and health, the consumers are reluctant to accept the technology in the marketplace.

Quantitative trait loci (QTL) analyse of recombinant inbred lines offers the potential to exploit allelic variation for the generation of improved traits without the use of GM [10]. In tomato this approach has been used successfully to isolate candidate genes regulating fruit yield and Brix content. Another non-GM approach to the generation of improved traits is TILLING [11]. In order to implement QTL and TILLING technologies, genetic crossing is required to introgress traits of interest into relevant backgrounds. This process is not precise and associated genetic regions are transposed simultaneously. Often these regions contain detrimental characteristics.

New Plant Breeding Technologies such as intragenesis and gene editing offer paradigm-changing opportunities to address future food and nutritional security concerns [12], through precision engineering that can be achieved without the presence of foreign DNA. However, to implement these technologies a comprehensive understanding of the key pathway components responsible for controlling the levels of these health conferring compounds is required. The present programme will identify, characterise and manipulate these key enzymes controlling biosynthesis of nutritional compounds, such as carotenoids and tocopherols.

Scientific approach. The present studentship opportunity is part of a larger programme directed towards generating a genetic and biochemical toolkit that will facilitate the nutritional enhancement of foods in a rapid background independent manner. In the present case tomato fruit will be used as it is both a crop and model system harbouring a wealth of exploitable genomic resources. Our focus will be nutritional isoprenoids such as carotenoids (provitamin A) and tocopherols (vitamin E). Existing genetic resources generated by the host laboratory with altered isoprenoids (carotenoids and tocopherols) levels in ripe tomato fruit will be characterised using modern “omic” technologies including transcriptomics, proteomics and metabolomics [13]. These approaches will be complemented by cellular biology to attribute ultrastructure components to metabolite sequestration. Collectively, these data (have) and will enable us to select precise gene candidate and their products (e.g., Phytoene synthase and deoxy-D-xylulose 5-phosphate), responsible for enhancing nutritional isoprenoids without the unintended effects often associated with transcription factors and regulators. Diverse alleles among populations of natural variation will also be analysed. To validate the effects of the candidate genes modulation using transient systems e.g. Virus-induced gene silencing (VIGS) and gene editing will be employed. These outputs will be characterised and routes to market application assessed.

Environment. The host laboratory is well funded and equipped, with dedicated GC-MS (x3), GC-FID, HPLC-PDA (x3), a HPLC-PDA-radiodetector, UPLC-PDA, and numerous real-time PCR machines. The laboratory has dedicated plant growth facilities. Customised MS libraries have been developed. High throughput modular cloning and Synthetic Biology resources. Recent investments include a suite of state-of-the-art hyphenated MS platforms. The group's involvement in European networks means that students are provided with the opportunity to carry out work in laboratories abroad as part of their interdisciplinary training. Collectively the studentship will provide excellent first-hand training in cell biology, biochemistry, molecular biology all in an applied format.


Funding Notes

Partial funding can be provided

References

[1]. Fraser, PD., and Bramley, PM., (2004). Prog.Lipid. Res. 43: 228. [2]. Anon (1988), In: The World Health Report. Life in the 21st Century. A Vision for All.
[3]. Department of Health. (1998) Report on Health and Social Subjects, 48, HMSO, London.
[4]. https://eatforum.org/content/uploads/2019/07/EAT-Lancet_Commission_Summary_Report.pdf.
[5]. Martin et al., (2011). Plant Cell, 23, 1685.
[6]. Roemer, S., et al., (2000). Nat.
Biotechnol. 18 : 666.
[7]. Fraser, PD. et al., (2002). PNAS. 99:1092.
[8]. Butelli et al., (2008). Nat. Biotechnol. 26, 1301.
[9]. Davuluri, et al., (2005). Nat. Biotechnol. 23: 890.
[10]. Paran, I. and Zamir, D. (2003) Tends in Genetics 19: 303.
[11]. Minoia et al., (2010) BMC research notes, 3, 69.
[12]. Enfissi et al., (2021). J.Plant Physiol. 258-259, 153378.
[13]. Enfissi et al., (2010). Plant Cell, 22, 1190.

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