Article

Plants need their vitamins too

Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
Current Opinion in Plant Biology (Impact Factor: 7.85). 07/2007; 10(3):266-75. DOI: 10.1016/j.pbi.2007.04.009
Source: PubMed

ABSTRACT

Over recent years, the pathways for the biosynthesis of many vitamins have been elucidated at the molecular level in plants, and several unique features are emerging. One is that the mitochondrion plays an important role in the synthesis of folate (vitamin B9), biotin (B7), pantothenate (B5), ascorbate (C), and possibly thiamin (B1). Second, the production of some of these cofactors is regulated by developmental cues, and perhaps more surprisingly, by environmental signals such as high light and salinity. Moreover, the biosynthesis of thiamin in Arabidopsis may be negatively regulated by a riboswitch, a novel method of gene regulation that is characteristic of cofactor biosynthesis in bacteria. Vitamin B12 is unique in that it is not found in vascular plants, but is abundant in algae; recent molecular work has revealed that algae do not synthesise the vitamin but instead obtain it from bacteria.

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Available from: Alison G Smith, Dec 16, 2015
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    • "Production mainly depends on the kind of carbon source in the culture media and on environmental factors, such as temperature and pH (Dahm et al. 1993; Rodelas et al. 1993). Functions and requirements for vitamins in plants and bacteria have been extensively studied (Smith et al. 2007 and references therein). Specifically, thiamine serves as a cofactor in diverse metabolic pathways in plants (Schyns et al. 2005). "
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    ABSTRACT: Thiamine release during synthetic mutualism between Chlorella sorokiniana co-immobilized in alginate beads with the microalgae growth-promoting bacterium Azospirillum brasilense was measured under stress conditions of pH, light intensity, and nitrogen starvation in short-term experiments. Thiamine release in the co-immobilized treatment was significantly higher at acidic pH compared to thiamine released by either microorganism alone. Under slightly alkaline pH, C. sorokiniana released the highest amount of thiamine. At stressful pH 6, the co-immobilized treatment released a higher quantity of thiamine than the sum of thiamine released by either microorganisms when immobilized separately. Release of thiamine by C. sorokiniana alone or co-immobilized was light intensity dependent; with higher the light intensity, more thiamine was released. Extreme light intensity negatively affected growth of the microalgae and release of thiamine. Nitrogen starvation during the first 24 h of culturing negatively affected release of thiamine by both microorganisms, where C. sorokiniana was more severely affected. Partial or continuous nitrogen starvation had similar negative effects on C. sorokiniana, but co-immobilization improved thiamine release. These results indicate that thiamine is released during synthetic mutualism between C. sorokiniana and A. brasilense, and this happens specifically during the alleviation of pH stress in the microalgae.
    Full-text · Article · Aug 2015 · Journal of Applied Phycology
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    • "Alternative solutions to obtain plant-specific vitamin derivatives at a larger scale are therefore desirable. Vitamin deficiency, overdose or imbalances are an issue for plants, too (Smith et al. 2007). Flexible adjustments of vitamin biosynthesis and metabolization partially account for the ability of plants to respond and adapt to environmentally challenging situations (Asensi-Fabado and Munne-Bosch 2010). "
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    ABSTRACT: Synthetic vitamin preparations have grown in popularity to combat health risks associated with an imbalanced diet, poor exercise and stress. In terms of bioavailability and diversity, they lack behind vitamins naturally occurring in plants. Solutions to obtain plant-derived vitamins at a larger scale are highly desirable. B vitamins act as precursors of enzymatic cofactors, thereby regulating important metabolic processes both in animals and plants. Because during plant germination, the vitamin content and micronutrient availability increase, sprouts are generally considered a healthier food as compared to dry grains. Germination only occurs if a plant′s antioxidant machinery is sufficiently activated to cope with oxidative stress. Seeds of quinoa, an edible gluten-free plant naturally rich in minerals, germinate readily in a solution containing the eight B vitamins. We studied biochemical changes during quinoa germination, with a focus on nutritionally relevant characteristics. The results are considered from a nutritional and plant physiological perspective. Germination of quinoa in vitamin-rich medium is a promising strategy to enhance the nutritional value of this matrix. Additional health-beneficial effects indirectly resulting from the vitamin treatment include elevated levels of the multi-functional amino acid proline and a higher antioxidant capacity. Plant biomolecules can be better protected from oxidative damage in vivo.
    Full-text · Article · Mar 2015 · Food Science & Nutrition
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    • "The goal here was to determine whether the sulfur group of Cys172 existed in both proteins and our ESR results showed that THI1 as well as THI1(A140V) are able to donate a sulfur to the synthesis of the thiazole. Additionally, we check the ability of mutated protein to produce the ADT molecule isolating the bound molecules from THI1 and THI1(A140V), as reported before by Smith et al. [15] for THI4. Our analysis reveals the existence of different bound compounds, for both proteins, but these molecules are present in different proportions in each protein. "
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    ABSTRACT: In eukaryotes, there are still steps of the vitamin B1 biosynthetic pathway not completely understood. In A. thaliana, THI1 protein has been associated with the synthesis of the thiazole ring, a finding supported by the identification of a thiamine pyrophosphate (TPP)-like compound in its structure. Here, we investigated THI1 and its mutant THI1(A140V), responsible for the thiamin auxotrophy in a A. thaliana mutant line, aiming to clarify the impact of this mutation in the stability and activity of THI1. Recently, the THI1 orthologue (THI4) was revealed to be the responsible for the donation of the sulfur atom from a cysteine residue to the thiazole ring in the thiamine intermediate. In this context, we carried out a cysteine quantification in THI1 and THI1(A140V) using electron spin resonance (ESR). These data showed that THI1(A140V) contains more sulfur-containing cysteines than THI1, indicating that the function as a sulfur donor is conserved, but the rate of donation reaction is somehow affected. Also, the bound compounds were isolated from both proteins and are present in different amounts in each protein. Unfolding studies presented differences in melting temperatures and also in the concentration of guanidine at which half of the protein unfolds, thus showing that THI1(A140V) has its conformational stability affected by the mutation. Hence, despite keeping its function in the early steps during the synthesis of TPP precursor, our studies have shown a decrease in the THI1(A140V) stability, which might be slowing down the biological activity of the mutant, and thus contributing to thiamin auxotrophy.
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