The biotechnological approach to improve performance or yield of crops or for engineering metabolic pathways requires the expression of a number of transgenes, each with a specific promoter to avoid induction of silencing mechanisms. In maize (Zea mays), used as a model for cereals, an efficient Agrobacterium tumefaciens-mediated transformation system has been established that is applied for translational research. In the current transformation vectors, the promoters of the 35S gene of the cauliflower mosaic virus and of the ubiquitin gene of maize are often used to drive the bialaphos-selectable marker and the transgene, respectively. To expand the number of promoters, genes with either constitutive or seed-specific expression were selected in Brachypodium distachyon, a model grass distantly related to maize. After the corresponding Brachypodium promoters had been fused to the β-glucuronidase reporter gene, their activity was followed throughout maize development and quantified in a fluorimetric assay with the 4-methylumbelliferyl β-D-glucuronide substrate. The promoters pBdEF1α and pBdUBI10 were constitutively and highly active in maize, whereas pBdGLU1 was clearly endosperm-specific, hence, expanding the toolbox for transgene analysis in maize. The data indicate that Brachypodium is an excellent resource for promoters for transgenic research in heterologous cereal species.

In higher plants, genetic transformation, which is part of the toolbox for the study of living organisms, had been reported only 30 years ago, boosting basic plant biology research, generating superior crops, and leading to the new discipline of plant biotechnology. Here, we review its principles and the corresponding molecular tools. In vitro regeneration, through somatic embryogenesis or organogenesis, is discussed because they are prerequisites for the subsequent Agrobacterium tumefaciens-mediated transferred (T)-DNA or direct DNA transfer methods to produce transgenic plants. Important molecular components of the T-DNA are examined, such as selectable marker genes that allow the selection of transformed cells in tissue cultures and are used to follow the gene of interest in the next generations, and reporter genes that have been developed to visualize promoter activities, protein localizations, and protein-protein interactions. Genes of interest are assembled with promoters and termination signals in Escherichia coli by means of GATEWAY-derived binary vectors that represent the current versatile cloning tools. Finally, future promising developments in transgene technology are considered. KEY WORDS: Agrobacterium tumefaciens, T-DNA, transgene, plant transformation, somatic embryogenesis, organogenesis Shoot regeneration in tissue cultureGenetic transformation usually involves DNA delivery to explants and subsequent tissue culture in which transformed cells are selected and induced either to form transgenic callus, shoots, roots, or somatic embryos. Hence, the tissue culture-induced regeneration capacity of a plant genotype is crucial for a successful genetic transformation. Indeed, recalcitrance to in vitro regeneration prevents genetic transformation in a large number of plant species or varieties. In vitro shoot regeneration competence has a genetic basis because it can be introgressed from a highly regenerative into a recalcitrant genotype (Koornneef et al., 1993;Anami et al., 2010). Therefore, identification of genes promoting or inhibiting the tissue culture-induced regeneration capacity will help to broaden the range of plant species for genetic transformation. Tissue culture regeneration occurs through organogenesis or somatic embryogenesis, which are discussed below and are schematically presented in Fig. 1. Int. J. Dev. Biol. 57: 483-494 (2013) doi: 10.1387/ijdb.130232mv www.intjdevbiol.com *Address correspondence to: Mieke Van Lijsebettens, VIB-Ghent University, Technologiepark 927, B-9052 Gent, Belgium. Tel.: +32 9 3313970. Fax: +32 9 3313809. E-mail: milij@psb.ugent.be #Note: These authors contributed equally to this work. Abbreviations used in this paper: GFP, green fluorescent protein; GUS, b-glucuronidase; T-DNA, transferred DNA; 2,4-D, 2,4-dichloro-phenoxyacetic acid; TALEN, transcription activator-like effector nuclease; vir, virulence; ZFN, zinc finger nuclease. Somatic embryogenesisSomatic embryos develop from undifferentiated somatic cells in cultures and are morphologically a...

Even though pesticides have greatly contributed to boosting agricultural productivity and farmer income over the years, there have been concerns about the safety of some of these pest control products. Besides, there has been a growing demand for good quality and safe food in the recent past – as reflected in the stringent regulations on pesticide residue levels in produce. Biopesticides in comparison with conventional synthetic chemical pesticides are usually less toxic, generally affect only the target pest and closely related organisms, are often effective in relatively small quantities and decompose faster, resulting in lower exposure. Consequently, over the last few years, biopesticides have attracted global attention as a safer pest control strategy for incorporation into Integrated Pest Management (IPM) programmes. Besides, in the last decade, adoption of IPM programmes has significantly enhanced pest management practices and, in some cases, reduced pesticide use, consequently reducing the rise in demand for synthetic chemical pesticides. Also, the development of new synthetic chemical pesticides has declined considerably in the recent past, as regulations have become tighter, with products being withdrawn from the market, resulting in a more limited choice of chemical solutions such that biopesticides have become a more feasible option. Many countries have also increasingly lowered chemical Maximum Residue Levels for agricultural imports which have made it increasingly necessary to explore pest control options which would ensure reduced reliance on the use of synthetic chemical pesticides. In this paper, avenues of addressing challenges to biopesticide research and development are evaluated by seeking the inputs of a wide range of stakeholders, building on a recent international workshop with biopesticides practitioners from across the globe. Prospects for biopesticide application are detailed using a case study on the fall armyworm (Spodoptera frugiperda) in Africa.

It has been over five years since the first report of an outbreak of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Africa. The highly invasive pest, native to the Americas, has since spread across the African continent attacking many crops and causing significant yield loss to Africa’s staple crop, maize. From the onset of the outbreak, there have been massive and varied responses from farmers, governments and nongovernmental organizations. This mini-review provides various perspectives on S. frugiperda control in sub-Saharan Africa, building on previously published evidence, and experiences of the authors. It also highlights new technologies and lessons learned so far from the S. frugiperda outbreaks in sub-Saharan Africa, based on which suggestions on possible integrated management approaches are proffered.