Towards the mineral biofortification of rice for food security
- Autores: Sonia Gomez Galera
- Directores de la Tesis: Ana Maria Pelacho Aja (codir. tes.), Paul Christou (codir. tes.)
- Lectura: En la Universitat de Lleida ( España ) en 2011
- Idioma: español
- Tribunal Calificador de la Tesis: Vicente Medina Piles (presid.), María Ángeles Achón Samá (secret.), Rosa María Cusidó Vidal (voc.), Antonio Pedro Martin Muñoz (voc.), Albert Boronat (voc.)
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- Resumen
Staple crops, especially cereal grains, are poor sources of essential minerals such as iodine (I), iron (Fe), zinc (Zn), calcium (Ca) and selenium (Se). The world¿s poorest people, who subsist on a monotonous cereal diet, are therefore the most vulnerable to mineral deficiency diseases. Malnutrition is a significant challenge, particularly in the developing world where measures that are commonplace in industrialized countries (varied diet, fortification schemes and dietary supplements) are largely absent. The biofortification of staple crops by genetic engineering is a promising strategy to increase the mineral content of cereal-based foods.
We established a combinatorial transgenic rice population by transformation with eight genes involved in the uptake, transport, accumulation and bioavailability of Fe, Zn and Se, aiming to produce grains containing substantially higher levels of these three key minerals. We selected two representative lines based on their potential enhanced mineral content and carried out experiments to gain insight into underlying mechanisms controlling transgene expression, the activity of the heterologous proteins, and their impact on mineral accumulation in planta. One line expressing an Fe transporter protein was able to take up the mineral more efficiently from alkaline soils and grew normally, whereas non-transgenic plants could not. This confirmed the ability of this Fe transporter to increase the mobility of Fe in the soil, but all the additional Fe accumulated in vegetative tissues suggesting the presence of an active partitioning mechanism that diverts Fe to vegetative tissues under limiting conditions. A second transgenic line simultaneously expressed four different transgenes but this was indistinguishable from non-transgenic plants in terms of alkaline soil tolerance and the accumulation of Fe, Zn, and Se. Mineral bioavailability is a key element in any biofortification-based intervention strategy to address mineral deficiencies, so bioavailability must be assessed carefully and strategies to enhance mineral bioavailability are required in order to establish dietary recommendations and ensure that mineral requirements are met in target populations. Genetically engineered crops accumulating high levels of bioavailable minerals are ideal for malnourished populations lacking access to diverse diets. Such crops would reduce hunger and improve the health and socioeconomic status of entire communities. However, many barriers prevent the deployment of such second-generation biotech crops, mainly reflecting the disharmonious regulations applied in different countries that depress international trade, and negatively influence public perception of biotechnology despite its clear benefits.
URL: http://hdl.handle.net/10803/63290
