Viroids, subviral pathogens of plants, are composed of a single-stranded circular RNA of 246–399 nucleotides. Within the 27 viroids sequenced, avocado sunblotch, peach latent mosaic and chrysanthemum chlorotic mottle viroids (ASBVd, PLMVd and CChMVd, respectively) can form hammerhead structures in both of their polarity strands. These ribozymes mediate self-cleavage of the oligomeric RNAs generated in the replication through a rolling circle mechanism, whose two other steps are catalyzed by an RNA polymerase and an RNA ligase. ASBVd, and presumably PLMVd and CChMVd, replicate and accumulate in the chloroplast, whereas typical viroids replicate and accumulate in the nucleus. PLMVd and CChMVd do not adopt a rod-like or quasi rod-like secondary structure as typical viroids do but have a highly branched conformation. A pathogenicity determinant has been mapped in a defined region of the CChMVd molecule.
The design and construction of a system consisting of a dielectric barrier cell and the electronic instrumentation intended to generate pulsed discharges at atmospheric pressure in water is showed in this paper. Also, the experimental results from the developed advanced oxidation processes (AOPs) are presented. Demineralised water with a conductivity of 5 μS/cm was used in all tests and a non-thermal plasma is produced between two concentric electrodes in a coaxial configuration by applying high voltage pulses which amplitude can be adjusted from 0 to 30 kV. The propagation of the streamers was characterized by means of the obtained waveforms of voltage and current. The concentration of the ozone generated by the discharges was monitored allowing, in this way, to carry out an analysis of the AOPs, and optic spectroscopy was used to study the discharge parameters involved in such a process.