[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

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Summary
The diets of over two-thirds of the world's population lack one or more essential mineral elements. This can be remedied through dietary diversification, mineral supplementation, food fortification, or increasing the concentrations and/or bioavailability of mineral elements in produce (biofortification). This article reviews aspects of soil science, plant physiology and genetics underpinning crop biofortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se). Two complementary approaches have been successfully adopted to increase the concentrations of bioavailable mineral elements in food crops. First, agronomic approaches optimizing the application of mineral fertilizers and/or improving the solubilization and mobilization of mineral elements in the soil have been implemented. Secondly, crops have been developed with: increased abilities to acquire mineral elements and accumulate them in edible tissues; increased concentrations of ‘promoter’ substances, such as ascorbate, β-carotene and cysteine-rich polypeptides which stimulate the absorption of essential mineral elements by the gut; and reduced concentrations of ‘antinutrients’, such as oxalate, polyphenolics or phytate, which interfere with their absorption. These approaches are addressing mineral malnutrition in humans globally.

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Biofortification of crops with seven mineral elements often lacking in human diets--iron, zinc, copper, calcium, magnesium, selenium and iodine.

Plant compounds that are perceived by humans to have color are generally referred to as 'pigments'. Their varied structures and colors have long fascinated chemists and biologists, who have examined their chemical and physical properties, their mode of synthesis, and their physiological and ecological roles. Plant pigments also have a long history of use by humans. The major classes of plant pigments, with the exception of the chlorophylls, are reviewed here. Anthocyanins, a class of flavonoids derived ultimately from phenylalanine, are water-soluble, synthesized in the cytosol, and localized in vacuoles. They provide a wide range of colors ranging from orange/red to violet/blue. In addition to various modifications to their structures, their specific color also depends on co-pigments, metal ions and pH. They are widely distributed in the plant kingdom. The lipid-soluble, yellow-to-red carotenoids, a subclass of terpenoids, are also distributed ubiquitously in plants. They are synthesized in chloroplasts and are essential to the integrity of the photosynthetic apparatus. Betalains, also conferring yellow-to-red colors, are nitrogen-containing water-soluble compounds derived from tyrosine that are found only in a limited number of plant lineages. In contrast to anthocyanins and carotenoids, the biosynthetic pathway of betalains is only partially understood. All three classes of pigments act as visible signals to attract insects, birds and animals for pollination and seed dispersal. They also protect plants from damage caused by UV and visible light.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-313X.2008.03447.x

Biosynthesis of plant pigments: anthocyanins, betalains and carotenoids

Recognizing the enormous potential of DNA markers in plant breeding, many agricultural research centers and plant breeding institutes have adopted the capacity for marker development and marker-assisted selection (MAS). However, due to rapid developments in marker technology, statistical methodology for identifying quantitative trait loci (QTLs) and the jargon used by molecular biologists, the utility of DNA markers in plant breeding may not be clearly understood by non-molecular biologists. This review provides an introduction to DNA markers and the concept of polymorphism, linkage analysis and map construction, the principles of QTL analysis and how markers may be applied in breeding programs using MAS. This review has been specifically written for readers who have only a basic knowledge of molecular biology and/or plant genetics. Its format is therefore ideal for conventional plant breeders, physiologists, pathologists, other plant scientists and students.

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An introduction to markers, quantitative trait loci (QTL) mapping and marker-assisted selection for crop improvement: The basic concepts

Carotenoid Metabolism in Plants

Polyphenol oxidases (PPOs; EC 1.10.3.2 or EC 1.14.18.1) catalyzing the oxygen-dependent oxidation of phenols to quinones are ubiquitous among angiosperms and assumed to be involved in plant defense against pests and pathogens. In order to investigate the role of PPO in plant disease resistance, we made transgenic tomato (Lycopersiconesculentum Mill. cv. Money Maker) plants that overexpressed a potato (Solanumtuberosum L.) PPO cDNA under control of the cauliflower mosaic virus 35S promoter. The transgenic plants expressed up to 30-fold increases in PPO transcripts and 5- to 10-fold increases in PPO activity and immunodetectable PPO. As expected, these PPO-overexpressing transgenic plants oxidized the endogenous phenolic substrate pool at a higher rate than control plants. Three independent transgenic lines were selected to assess their interaction with the bacterial pathogen Pseudomonassyringae pv. tomato. The PPO-overexpressing tomato plants exhibited a great increase in resistance to P.syringae. Compared with control plants, these transgenic lines showed less severity of disease symptoms, with over 15-fold fewer lesions, and strong inhibition of bacterial growth, with over 100-fold reduction of bacterial population in the infected leaves. These results demonstrate the importance of PPO-mediated phenolic oxidation in restricting plant disease development.

Overexpression of polyphenol oxidase in transgenic tomato plants results in enhanced bacterial disease resistance.

Despite recent progress in our understanding of carotenogenesis in plants, the mechanisms that govern overall carotenoid accumulation remain largely unknown. The Orange (Or) gene mutation in cauliflower (Brassica oleracea var botrytis) confers the accumulation of high levels of β-carotene in various tissues normally devoid of carotenoids. Using positional cloning, we isolated the gene representing Or and verified it by functional complementation in wild-type cauliflower. Or encodes a plastid-associated protein containing a DnaJ Cys-rich domain. The Or gene mutation is due to the insertion of a long terminal repeat retrotransposon in the Or allele. Or appears to be plant specific and is highly conserved among divergent plant species. Analyses of the gene, the gene product, and the cytological effects of the Or transgene suggest that the functional role of Or is associated with a cellular process that triggers the differentiation of proplastids or other noncolored plastids into chromoplasts for carotenoid accumulation. Moreover, we demonstrate that Or can be used as a novel genetic tool to induce carotenoid accumulation in a major staple food crop. We show here that controlling the formation of chromoplasts is an important mechanism by which carotenoid accumulation is regulated in plants.

The Cauliflower Or Gene Encodes a DnaJ Cysteine-Rich Domain-Containing Protein That Mediates High Levels of β-Carotene Accumulation

Carotenoid Metabolism in Plants: The Role of Plastids.

Carotenoids are a diverse group of pigments widely distributed in nature. The vivid yellow, orange, and red colors of many horticultural crops are attributed to the overaccumulation of carotenoids, which contribute to a critical agronomic trait for flowers and an important quality trait for fruits and vegetables. Not only do carotenoids give horticultural crops their visual appeal, they also enhance nutritional value and health benefits for humans. As a result, carotenoid research in horticultural crops has grown exponentially over the last decade. These investigations have advanced our fundamental understanding of carotenoid metabolism and regulation in plants. In this review, we provide an overview of carotenoid biosynthesis, degradation, and accumulation in horticultural crops and highlight recent achievements in our understanding of carotenoid metabolic regulation in vegetables, fruits, and flowers.

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Li Li

Papers

Carotenoid Metabolism in Plants

Overexpression of polyphenol oxidase in transgenic tomato plants results in enhanced bacterial disease resistance.

The Cauliflower Or Gene Encodes a DnaJ Cysteine-Rich Domain-Containing Protein That Mediates High Levels of β-Carotene Accumulation

Carotenoid Metabolism in Plants: The Role of Plastids.

Carotenoid metabolism and regulation in horticultural crops.