Agrobacterium - and microprojectile - mediated viral DNA delivery into barley microspore-derived cultures

Geminivirus-Derived Vectors as Tools for Functional Genomics

A persistent issue in the agricultural sector worldwide is the intensive damage caused to crops by the geminivirus family of viruses. The diverse types of viruses, rapid virus evolution rate, and broad host range make this group of viruses one of the most devastating in nature, leading to millions of dollars' worth of crop damage. Geminiviruses have a small genome and can be either monopartite or bipartite, with or without satellites. Their ability to independently replicate within the plant without integration into the host genome and the relatively easy handling make them excellent candidates for plant bioengineering. This aspect is of great importance as geminiviruses can act as natural nanoparticles in plants which can be utilized for a plethora of functions ranging from vaccine development systems to geminivirus-induced gene silencing (GIGS), through deconstructed viral vectors. Thus, the investigation of these plant viruses is pertinent to understanding their crucial roles in nature and subsequently utilizing them as beneficial tools in functional genomics. This review, therefore, highlights some of the characteristics of these viruses that can be deemed significant and the subsequent successful case studies for exploitation of these potentially significant pathogens for role mining in functional biology.

Geminiviruses: plant viral vectors

Geminiviruses are being used as convenient autonomously replicating vectors for foreign gene amplification in plants. Using tissue culture techniques, they have been adapted for the analysis of the regulation of gene expression in a wide range of hosts, including both mono- and dicotyledonous species. In monocotyledonous plants that are particularly recalcitrant to transformation, geminivirus symptom-induction has been used as a sensitive marker for DNA uptake.

Transformation of microbes, plants and animals by particle bombardment

Over the past several years, particle bombardment has evolved into a useful tool for molecular biologists, allowing direct gene transfer to a broad range of cell and tissue types. Some of the important applications of the process include the production of transgenic crop species including maize and soybean and the introduction of DNA into plastids and mitochondria. Recent results have extended the range of gene transfer by particle bombardment to animal and bacterial cells. One noteworthy newer application is the direct insertion of genes into the organs of living animals. Here we discuss these advances and the instrument developments that contributed to them.

Stable transformation of barley via PEG-induced direct DNA uptake into protoplasts

Protoplasts isolated from a barley cell suspension (cv Dissa) were transformed with plasmid DNA containing the neomycinphosphotransferase II (NPT) and β-glucuronidase (GUS) genes, using polyethyleneglycol (PEG) to induce DNA uptake. Transformed microcalli were selected in media containing G418 sulphate. NPT activity was detected in all antibiotic-resistant cell lines, but not all NPT-positive cell lines had GUS activity. Southern analysis confirmed the presence of sequences homologous to the APT and GUS genes in DNA of G418-resistant callus.