Plant biotechnology for crop improvement

The typical crop improvement cycle takes 10–15 years to complete and includes germplasm manipulations, genotype selection and stabilization, variety testing, variety increase, proprietary protection and crop production stages. Plant tissue culture and genetic engineering procedures that form the basis of plant biotechnology can contribute to most of these crop improvement stages. This review provides an overview of the opportunities presented by the integration of plant biotechnology into plant improvement efforts and raises some of the societal issues that need to be considered in their application.     

Energy crop and biotechnology for biofuel production

Selection of energy crops is the first priority for large-scale biofuel production in China.As a major topic, it was extensively discussed in the Second International Symposium on Bioenergy and Biotechnology, held from October 16-19(th), 2010 in Huazhong Agricultural University(HZAU), Wuhan, China, with more than one hundred registered participants(Figure 1).     

Plastid biotechnology for crop production: present status and future perspectives

The world population is expected to reach an estimated 9.2 billion by 2050. Therefore, food production globally has to increase by 70% in order to feed the world, while total arable land, which has reached its maximal utilization, may even decrease. Moreover, climate change adds yet another challenge to global food security. In order to feed the world in 2050, biotechnological advances in modern agriculture are essential. Plant genetic engineering, which has created a new wave of global crop production after the first green revolution, will continue to play an important role in modern agriculture to meet these challenges. Plastid genetic engineering, with several unique advantages including transgene containment, has made significant progress in the last two decades in various biotechnology applications including development of crops with high levels of resistance to insects, bacterial, fungal and viral diseases, different types of herbicides, drought, salt and cold tolerance, cytoplasmic male sterility, metabolic engineering, phytoremediation of toxic metals and production of many vaccine antigens, biopharmaceuticals and biofuels. However, useful traits should be engineered via chloroplast genomes of several major crops. This review provides insight into the current state of the art of plastid engineering in relation to agricultural production, especially for engineering agronomic traits. Understanding the bottleneck of this technology and challenges for improvement of major crops in a changing climate are discussed.     

Root-targeted biotechnology to mediate hormonal signalling and improve crop stress tolerance

Since plant root systems capture both water and nutrients essential for the formation of crop yield, there has been renewed biotechnological focus on root system improvement. Although water and nutrient uptake can be facilitated by membrane proteins known as aquaporins and nutrient transporters, respectively, there is a little evidence that root-localised overexpression of these proteins improves plant growth or stress tolerance. Recent work suggests that the major classes of phytohormones are involved not only in regulating aquaporin and nutrient transporter expression and activity, but also in sculpting root system architecture. Root-specific expression of plant and bacterial phytohormone-related genes, using either root-specific or root-inducible promoters or grafting non-transformed plants onto constitutive hormone producing rootstocks, has examined the role of root hormone production in mediating crop stress tolerance. Root-specific traits such as root system architecture, sensing of edaphic stress and root-to-shoot communication can be exploited to improve resource (water and nutrients) capture and plant development under resource-limited conditions. Thus, root system engineering provides new opportunities to maintain sustainable crop production under changing environmental conditions.     

Gibberellin biosynthesis in fungi: genes, enzymes, evolution, and impact on biotechnology

Gibberellins (GAs) constitute a large family of tetracyclic diterpenoid carboxylic acids, some members of which function as growth hormones in higher plants. As well as being phytohormones, GAs are also present in some fungi and bacteria. In recent years, GA biosynthetic genes from Fusarium fujikuroi and Arabidopsis thaliana have been cloned and well characterised. Although higher plants and the fungus both produce structurally identical GAs, there are important differences indicating that GA biosynthetic pathways have evolved independently in higher plants and fungi. The fact that horizontal gene transfer of GA genes from the plant to the fungus can be excluded, and that GA genes are obviously missing in closely related Fusarium species, raises the question of the origin of fungal GA biosynthetic genes. Besides characterisation of F. fujikuroi GA pathway genes, much progress has been made in the molecular analysis of regulatory mechanisms, especially the nitrogen metabolite repression controlling fungal GA biosynthesis. Basic research in this field has been shown to have an impact on biotechnology. Cloning of genes, construction of knock-out mutants, gene amplification, and regulation studies at the molecular level are powerful tools for improvement of production strains. Besides increased yields of the final product, GA₃, it is now possible to produce intermediates of the GA biosynthetic pathway, such as ent-kaurene, ent-kaurenoic acid, and GA₁₄, in high amounts using different knock-out mutants. This review concentrates mainly on the fungal biosynthetic pathway, the genes and enzymes involved, the regulation network, the biotechnological relevance of recent studies, and on evolutionary aspects of GA biosynthetic genes.     

Global capture of crop biotechnology in developing world over a decade

There is an urgent need for the advancement of agricultural technology (e.g. crop biotechnology or genetic modification (GM) technology), particularly, to address food security problem, to fight against hunger and poverty crisis and to ensure sustainable agricultural production in developing countries. Over the past decade, the adoption of GM technology on a commercial basis has increased steadily around the world with a significant impact in terms of socio-economic, environment and human health benefits. However, GM technology is still surrounded by controversial debates with several factors hindering the adoption of GM crops. This paper reviews current literatures on commercial production of GM crops, and assesses the benefits and constraints associated with adoption of GM crops in developing countries in the last 15 years. This article provides policy implication towards advancing the development and adoption of GM technology in developing countries and concludes with summary of key points discussed.     

Pharmaceutical biotechnology, Chemical biotechnology: Web alert

A selection of World Wide Web sites relevant to papers published in this issue of Current Opinion in Biotechnology.     

Infertility,abortion, and biotechnology

Patterns of reproductive failure described in humans and other mammals suggest that reproductive failure may in many instances be the result of adaptations evolved to suppress reproduction under temporarily harsh conditions. By suppressing reproduction under such conditions, females are able to conserve their time and energy for reproductive opportunities in which reproduction is most likely to succeed. Such adaptations have been particularly important for female mammals, given (a) the amount of time and energy that reproduction requires, and (b) the degree to which reproductive conditions can vary. The existence of conscious and unconscious mechanisms to suppress reproduction under poor conditions has several implications for obstetric/gynecologic practices. Two implications are discussed with reference to biotechnological advancements in our ability to facilitate conceptions and manage problem pregnancies: (a) potential dangers of sophisticated technologies overriding natural fertility controls; and (b) the need for greater appreciation of the association between psychosocial stress and reproductive failure in the treatment of reproductive problems. Implications for elective abortion practices are discussed as well. The ideas for this paper were developed while the author was a recipient of a Career Development Award from the Harry Frank Guggenheim Foundation. Dr. Wasser received a B.S. degree of Zoology from Michigan State University in 1975, a Masters of Science in Zoology from the University of Wisconsin-Milwaukee in 1976, and a Ph.D. in Psychology from the University of Washington in 1981. He is co-director of the Animal Behavior Research Unit, a long-term study on the behavioral ecology and reproduction of free-ranging yellow baboons at Mikumi National Park, Tanzania. Dr. Wasser’s primary research focus is on the evolution of reproductive strategies in female mammals. His work includes research on human infertility and abortion. He is also working on the breeding of endangered species in captivity under a Research Development Award from the National Zoological Park of the Smithsonian Institution.     

Molecular mapping and tagging of genes in crop plants

In India, molecular mapping and tagging of agronomically important genes using RFLP and RAPD markers have been carried out in three different crops: rice, mustard and chickpea. In rice, tagging of genes for resistance to gall midge and blast has been accomplished. Molecular mapping of cooking quality traits in rice is in progress. For fingerpringting rice cultivars, suitable probe enzyme combinations have been identified. In mustard, a partial RFLP linkage map has been constructed and one of the yellow seed-coat colour loci has been mapped. Significant associations of RFLP markers with quantitative traits have also been established. Potential use of RAPD markers to identify heterotic groups among mustard accessions has been demonstrated. In chickpea, the occurrence of considerable interspecific DNA polymorphism as revealed by RAPD analysis has facilitated construction of a partial linkage map.     

The influence of genetics on future crop production strategies: from traits to genes, and genes to traits

This paper discusses how a genetical approach to plant physiology can contribute to research underpinning the production of new crop varieties. It highlights the interactions between genetics and plant breeding and how the current advances in genetics and the new science of genomics can contribute to our understanding of the genetical control of key agronomic traits ‐ the process of ‘translating’ traits to identified and mapped genes. Advances in genomics, such as the sequencing of whole genomes and expressed sequence tags, are producing information on genes and gene structures, but without knowing their function. A great deal more biology will be necessary to translate gene structure to function ‐ the process of translating genes to traits. Combining these ‘forward’ and ‘reverse’ genetic approaches will allow us to get comprehensive knowledge of the biology of agronomic traits at the physiological, biochemical and molecular levels, so that the ‘circuitry’ of our crop plants can be elucidated. This will enable plant breeders to manipulate crop phenotype using marker‐assisted breeding or genetic engineering approaches with a precision not previously possible.     

转基因植物标记基因的安全技术

转基因植物中抗性标记基因潜在的生态和食用安全性一直是颇有争论且悬而未决的问题。解决的途径有2条：一是选用安全性标记基因;二是开发、应用删除抗性标记基因新技术。综述了这两方面的研究进展。     

Phytase enzymology, applications, and biotechnology

Phytases are phosphohydrolases that initiate the step-wise removal of phosphate from phytate. These enzymes have been widely used in animal feeding to improve phosphorus nutrition and to reduce phosphorus pollution of animal waste. The potential of phytases in improving human nutrition of essential trace minerals in plant-derived foods is being explored. This review covers the basic biochemistry and application of phytases, and emphasizes the emerging biotechnology used for developing new effective phytases with improved properties.     

Prospects for applications ofrol genes for crop improvement

Prospects for the applications ofrol genes for crop improvement are discussed. As suggested in many reports, rol genes are suitable tools to modify plant developmental processes, such as formation of adventitious roots and release of axillary buds from apical dominance. Practical applications, however, might be hampered by the many pleiotropic side effects that are observed in plants transformed withrol genes. Alternative approaches need to be developed, therefore, to overcome these undesired effects. We offer a novel approach for application that is clearly different from earlier strategies, and that is based on the application ofrol genes incombination plants; i.e., plants consisting of an untransformed scion grafted on a rootstock transformed with arol gene. In rose it was demonstrated for the first time that expression ofrol genes in rootstocks led to an accelerated release of axillary buds of the untransformed scion, but without the transmission of many undesired pleiotropic effects. We expect that this stimulation will result in a changed plant architecture leading to a more efficient production of roses. Alternatively, the pleiotropic effects may be overcome by employingrol genes that are driven by organ- or tissue-specific promoters, leading to a more defined expression of these genes.