To develop a new easy and quick gene delivery system for any types of plants, we prepared ionic complexes of plasmid DNA with designed peptide carriers, each of which combined a cell-penetrating peptide (Bp100 or Tat(2)) with a polycation (nona-arginine or a copolymer of histidine and lysine). The present system via the designed peptides demonstrated rapid and efficient transient transfections into intact leaf cells of Nicotiana benthamiana and Arabidopsis thaliana without protoplast preparations. The designed peptides demonstrated significantly higher transfection efficiency in comparison to the nonfusion peptides (Bp100, Tat2, nona-arginine, and copolymer of histidine and lysine), indicating that the combination of functional peptides was a key to develop an efficient peptide-based gene delivery system. On the basis of the results, we exhibited the versatility of the designed peptide-based gene delivery system, which will explore the application of plant biotechnology.

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Polyhydroxyalkanoates (PHAs) are a potential replacement for some petrochemical-based plastics. PHAs are polyesters synthesized and stored by various bacteria and archaea in their cytoplasm as water-insoluble inclusions. PHAs are usually produced when the microbes are cultured with nutrient-limiting concentrations of nitrogen, phosphorus, sulfur, or oxygen and excess carbon sources. Such fermentation conditions have been optimized by industry to reduce the cost of PHAs produced commercially. Industrially, these biodegradable polyesters are derived from microbial fermentation processes utilizing various carbon sources. One of the major constraints in scaling-up PHA production is the cost of the carbon source metabolized by the microorganisms. Hence, cheap and renewable carbon substrates are currently being investigated around the globe. Plant and animal oils have been demonstrated to be excellent carbon sources for high yield production of PHAs. Waste streams from oil mills or the used oils, which are even cheaper, are also used. This approach not only reduces the production cost for PHAs, but also makes a significant contribution toward the reduction of environmental pollution caused by the used oil. Advancements in the genetic and metabolic engineering of bacterial strains have enabled a more efficient utilization of various carbon sources, in achieving high PHA yields with specified monomer compositions. This review discusses recent developments in the biosynthesis and classification of various forms of PHAs produced using crude and waste oils from the oil palm and fish industries. The biodegradability of the PHAs produced from these oils will also be discussed.

Introducing exogenous genes into plant cells is an essential technique in many fields in plant science and biotechnology. Despite their huge advantages, disadvantages of current transfection methods include the requirement of expensive equipment, risk of gene damage, low transformation efficiency, transgene size limitations, and limitations of applicable plant types. Recently developed peptide-based gene carriers can deliver plasmid and double-stranded RNA. However, the delivery of double-stranded DNA (dsDNA), specifically PCR products, has not been studied. As dsDNA is handled in several plant science labs, peptide-based gene carriers are expected to be applicable to dsDNA in addition to plasmid DNA and double-stranded RNA. Here, we demonstrate dsDNA introduction into intact Nicotiana benthamiana leaves by using an ionic complex of a fusion peptide comprising (KH) 9 and Bp100 with dsDNA encoding Renilla luciferase as a reporter gene. The buffer condition for the complex preparation and infiltration significantly affected the transfection efficiency; this is because the structure of the complex in various protonated conditions contributed to the transfection efficiency. Structures of the complex and peptide are key factors for improving the peptide-based gene delivery system for plants.

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