Biofortificação de plantas de alface (Lactuca sativa L.) geneticamente modificadas para aumento do teor de folato

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Folate is a complex B vitamin, water-soluble, formed by pterine, para-aminonzoic acid (pABA) and one to eight parts of glutamate. Some studies suggest that its deficiency in pregnant women is related to miscarriage, and that in the foetus it is related to defects of the neural tube, anencephalia, anacephalia, spine bifide, leporine lip and Down syndrome, and establish a relation between diets with inadequate folate levels and the appearance of congenital defects, problems in the cognitive development, increase in the risk of cardiovascular diseases, schizophrenia, Alzheimers disease, megaloblastic anemia and depression. The lettuce plant was chosen to have its folate level increased because it is a vegetable cultivated and consumed throughout the world, in natura, and because it has its transformation protocol established. We have transformed two metabolic ways of folate: the way of pterines and the way of pABA. For such purpose two systems have been used in parallel: a system mediated by Agrobacterium tumefaciens in which we have transfered the codifying region of the gene GTP ciclohidrolase I (gchI), which catalizes the first step in the metabolic way of the pterines. The gene of the gchI was synthetized based on a sequence of Gallus gallus with the optimization of codons for the expression in lettuce, under control of the promoter 35S dCaMV. In the way of pABA we used the bombardment system, in which we inserted the codifying region of the gene corismato sintase (lecs) of tomato (Solanum lycopersicum =Lycopercicon esculentum) in the lettuce chloroplastic genome, which catalyses the first step of this pathway. We obtained 29 lineages of lettuce containing the transgene gchI and 4 lineages containing the transgene lecs. Plants of the generation T1 were analysed for the quantification of total folates by means of the microbiological method with Lactobacillus rhamnosus (ATCC7469). The results show there has been a increase in up to 8.5 times in the folate level in transgenic lineages expressing gchI and 1.8 times in transgenic lineages transformed with lecs, when compared to non transformed plants. These lineages will be used in experiments for the determination of the bioavailability of folate in animals.

ASSUNTO(S)

biologia molecular transformação nuclear agrobacterium tumefaciens folato corismato sintase transformação cloroplasmática gtp ciclohidrolase alface transformação genética

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