The Sesame Genome Working Group (SGWG) has been formed to sequence and assemble the sesame (Sesamum indicum L.) genome. The status of this project and our planned analyses are described.

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Genome sequencing of the important oilseed crop Sesamum indicum L

Reactive oxygen species (ROS) originate as a natural byproduct in standard metabolism of oxygen activities. The principal sites of ROS generation in the cell are apoplast, mitochondria, chloroplasts, and peroxisomes. These ROS can induce cellular injuries by proteins oxidation, lipid peroxidation, and DNA damage, which finally may result in plant cellular death. Under regular circumstances, there is a steadiness between generation and elimination of ROS, but this balance is hampered by different biotic and abiotic stress factors such as exposure to heavy metals, high and low-light conditions, pathogens, insects and temperature extremes, resulting in a high generation of ROS which should be counteracted by the antioxidant machinery in cells. The antioxidant system of defense is composed by two groups: (i) Enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), general peroxidases (PRX) (e.g. guaiacol peroxidase GPX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR); (ii) Non-enzymatic antioxidants such as ascorbic acid (AA), reduced glutathione (GSH), α-tocopherol, carotenoids, plastoquinone/ubiquinone and flavonoids. These two groups of metabolites and enzymes work together with the main aim of ROS scavenging, but also in determining plant signaling, immune response, and plant growth and development. Finally, the molecular genetics of ROS genes and related metabolic pathways are briefly outlined, including gene isoforms, cellular localization, detection methods used and interactions amongst them. This information is crucial in better understanding and designing procedures for plants´stress tolerance; leading to a better management of agricultural plants under challenging and changing climatic conditions and food security.

Oxidative Stress and Antioxidant Metabolism under Adverse Environmental Conditions: a Review

Sesame (Sesamum indicum L.) is one of the oldest oilseed crops widely grown in Africa and Asia for its high-quality nutritional seeds. It is well adapted to harsh environments and constitutes an alternative cash crop for smallholders in developing countries. Despite its economic and nutritional importance, sesame is considered as an orphan crop because it has received very little attention from science. As a consequence, it lags behind the other major oil crops as far as genetic improvement is concerned. In recent years, the scenario has considerably changed with the decoding of the sesame nuclear genome leading to the development of various genomic resources including molecular markers, comprehensive genetic maps, high-quality transcriptome assemblies, web-based functional databases and diverse daft genome sequences. The availability of these tools in association with the discovery of candidate genes and QTLs for key agronomic traits including high oil content and quality, waterlogging and drought tolerance, disease resistance, cytoplasmic male sterility, high yield, pave the way to the development of some new strategies for sesame genetic improvement. As a result, sesame has graduated from an “orphan crop” to a “genomic resource-rich crop”. With the limited research teams working on sesame worldwide, more synergic efforts are needed to integrate these resources in sesame breeding for productivity upsurge, ensuring food security and improved livelihood in developing countries. This review retraces the evolution of sesame research by highlighting the recent advances in the “Omics” area and also critically discusses the future prospects for a further genetic improvement and a better expansion of this crop.

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The Emerging Oilseed Crop Sesamum indicum Enters the "Omics" Era.

Plastoquinone (PQ) and ubiquinone (UQ) are two important prenylquinones, functioning as electron transporters in the electron transport chain of oxygenic photosynthesis and the aerobic respiratory chain, respectively, and play indispensable roles in plant growth and development through participating in the biosynthesis and metabolism of important chemical compounds, acting as antioxidants, being involved in plant response to stress, and regulating gene expression and cell signal transduction. UQ, particularly UQ10, has also been widely used in people’s life. It is effective in treating cardiovascular diseases, chronic gingivitis and periodontitis, and shows favorable impact on cancer treatment and human reproductive health. PQ and UQ are made up of an active benzoquinone ring attached to a polyisoprenoid side chain. Biosynthesis of PQ and UQ is very complicated with more than thirty five enzymes involved. Their synthetic pathways can be generally divided into two stages. The first stage leads to the biosynthesis of precursors of benzene quinone ring and prenyl side chain. The benzene quinone ring for UQ is synthesized from tyrosine or phenylalanine, whereas the ring for PQ is derived from tyrosine. The prenyl side chains of PQ and UQ are derived from glyceraldehyde 3-phosphate and pyruvate through the 2-C-methyl-D-erythritol 4-phosphate pathway and/or acetyl-CoA and acetoacetyl-CoA through the mevalonate pathway. The second stage includes the condensation of ring and side chain and subsequent modification. Homogentisate solanesyltransferase, 4-hydroxybenzoate polyprenyl diphosphate transferase and a series of benzene quinone ring modification enzymes are involved in this stage. PQ exists in plants, while UQ widely presents in plants, animals and microbes. Many enzymes and their encoding genes involved in PQ and UQ biosynthesis have been intensively studied recently. Metabolic engineering of UQ10 in plants, such as rice and tobacco, has also been tested. In this review, we summarize and discuss recent research progresses in the biosynthetic pathways of PQ and UQ and enzymes and their encoding genes involved in side chain elongation and in the second stage of PQ and UQ biosynthesis. Physiological functions of PQ and UQ played in plants as well as the practical application and metabolic engineering of PQ and UQ are also included.

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Plastoquinone and Ubiquinone in Plants: Biosynthesis, Physiological Function and Metabolic Engineering.

Rice is a staple food for more than 3 billion people in more than 100 countries of the world but ironically it is deficient in many bioavailable vitamins, minerals, essential amino- and fatty-acids and phytochemicals that prevent chronic diseases like type 2 diabetes, heart disease, cancers, and obesity. To enhance the nutritional and other quality aspects of rice, a better understanding of the regulation of the processes involved in the synthesis, uptake, transport, and metabolism of macro-(starch, seed storage protein and lipid) and micronutrients (vitamins, minerals and phytochemicals) is required. With the publication of high quality genomic sequence of rice, significant progress has been made in identification, isolation, and characterization of novel genes and their regulation for the nutritional and quality enhancement of rice. During the last decade, numerous efforts have been made to refine the nutritional and other quality traits either by using the traditional breeding with high through...

Progress and challenges in improving the nutritional quality of rice (Oryza sativa L.)

Sesame (Sesamum indicum L.) is an important oilseed crop grown in India, China, Korea, Russia, Turkey, Mexico, South America, and several countries of Africa. Sesame seeds are rich in oil, proteins, unsaturated fatty acids, vitamins, minerals, and folic acid. Nearly 70% of the world's sesame is processed into oil and meal, while the remainder is channeled to food and confectionery industries. Production of sesame is limited by several fungal diseases, water logging, salinity, and shattering of seed capsules during harvest. Introgression of useful genes from wild species into cultigens by conventional breeding has not been successful due to postfertilization barriers. The only alternative for the improvement of S. indicum is to transfer genes from other sources through genetic transformation techniques. Here, we describe a simple, fast, and reproducible method for the Agrobacterium-mediated genetic transformation of S. indicum which may be employed for the transfer of desirable traits into this economically important oilseed crop.

Sesame (Sesamum indicum L.).

Coenzyme Q10 (CoQ10) or Ubiquinone10 (UQ10), an isoprenylated benzoquinone, is well-known for its role as an electron carrier in aerobic respiration It is a sole representative of lipid soluble antioxidant that is synthesized in our body In recent years, it has been found to be associated with a range of patho-physiological conditions and its oral administration has also reported to be of therapeutic value in a wide spectrum of chronic diseases Additionally, as an antioxidant, it has been widely used as an ingredient in dietary supplements, neutraceuticals, and functional foods as well as in anti-aging creams Since its limited dietary uptake and decrease in its endogenous synthesis in the body with age and under various diseases states warrants its adequate supply from an external source To meet its growing demand for pharmaceutical, cosmetic and food industries, there is a great interest in the commercial production of CoQ10 Various synthetic and fermentation of microbial natural producers and their mutated strains have been developed for its commercial production Although, microbial production is the major industrial source of CoQ10 but due to low yield and high production cost, other cost-effective and alternative sources need to be explored Plants, being photosynthetic, producing high biomass and the engineering of pathways for producing CoQ10 directly in food crops will eliminate the additional step for purification and thus could be used as an ideal and cost-effective alternative to chemical synthesis and microbial production of CoQ10 A better understanding of CoQ10 biosynthetic enzymes and their regulation in model systems like E coli and yeast has led to the use of metabolic engineering to enhance CoQ10 production not only in microbes but also in plants The plant-based CoQ10 production has emerged as a cost-effective and environment-friendly approach capable of supplying CoQ10 in ample amounts The current strategies, progress and constraints of CoQ10 production in plants are discussed in this review

Coenzyme Q10 production in plants: current status and future prospects

A simple, efficient, reproducible and comparatively genotype-independent in vitro plant regeneration protocol was developed for ten commercial Indian bread wheat cultivars using mature embryos as the explants. Three different auxins and five different combinations of growth regulators in a modified Murashige and Skoog’s basal medium were assessed for their effect on callus induction and plant regeneration, respectively, in a high yielding and widely grown cultivar, PBW-343. The optimized conditions were further evaluated with nine other commercial cultivars. A simple novel approach of physical isolation of regenerable calli from non regenerable structures during the early callus phase was used to improve plant regeneration. Callus induced on 2.0 mg-1 2,4-dichlorophenoxyacetic acid (2,4-D) showed a regeneration frequency of 86 % with 7.5 shoots per explants on hormone-free medium. A considerable improvement in the regeneration frequency (up to 97 %) and the average of shoots (19 shoots per explants) was obtained with a combination of thidiazuron (TDZ) and 2,4-D.

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Plant regeneration from mature embryo of commercial Indian bread wheat ( Triticum aestivum L.) cultivars

Coenzyme Q (CoQ), an electron carrier of the mitochondrial respiratory chain and a potent antioxidant, consists of a benzoquinone head and an isoprenoid side chain of varying numbers of isoprene units, 10 in humans, animals and some microbes including Agrobacterium tumefaciens (CoQ10), 9 in Arabidopsis and cereals (CoQ9) and 8 in Escherichia coli (CoQ8). The synthesis of CoQ10 side chain is catalyzed by a single side chain length determining enzyme, decaprenyl diphosphate synthase (DPS) which is encoded by a dps gene. We report here, the isolation and sequencing of a dps gene from A. tumefaciens strain LBA4404 and its cloning in pET28a expression vector of E. coli BL21 (DE3) strain to produce and purify recombinant DPS protein for the production of its antibodies in rabbit. The dps gene isolated from A. tumefaciens consists of 1077 bp efficient for encoding a polypeptide of 359 amino acids with a molecular mass of around 39 kDa. DPS protein expression was induced by adding isopropyl β-D-1-thiogalactopyranoside in bacterial culture to a final concentration of 1.0 mM. Recombinant protein tagged with histidine at N-terminal was purified by immobilized metal-affinity chromatography. The purified DPS protein was capable of producing polyclonal antibodies in rabbit whose specificity to DPS enzyme was confirmed by the western blot analysis. Expression of dps gene in E. coli extended the side chain length of CoQ8 to 10 isopenoid units and produced CoQ10 in addition to CoQ8. This is the first report on the production of polyclonal antibodies against recombinant DPS protein and demonstration of their utility.

Sanjay Singh Parmar

Papers

Sesame (Sesamum indicum L.).

Coenzyme Q10 production in plants: current status and future prospects

Plant regeneration from mature embryo of commercial Indian bread wheat ( Triticum aestivum L.) cultivars

Generation of polyclonal antibodies against recombinant Agrobacterium tumefaciens decaprenyl diphosphate synthase produced in Escherichia coli