Enhanced electroporation in plant tissues via low frequency pulsed electric fields: Influence of cytoplasmic streaming

Abstract

Pulsed electric fields (PEF) are known to be effective at permeabilizing plant tissues. Prior research has demonstrated that lower pulse frequencies induce higher rates of permeabilization, but the underlying reason for this response is unclear. Intriguingly, recent microscopic observations with onion tissues have also revealed a correlation between PEF frequency and the subsequent speed of intracellular convective motion, i.e., cytoplasmic streaming. In this paper, we investigate the effect of cytoplasmic streaming on the efficacy of plant tissue permeabilization via PEF. Onion tissue samples were treated with Cytochalasin B, a known inhibitor of cytoplasmic streaming, and changes in cellular integrity and viability were measured over a wide range of frequencies and field strengths. We find that at low frequencies (f < 1 Hz), the absence of cytoplasmic streaming results in a 19% decrease in the conductivity disintegration index compared with control samples. Qualitatively, similar results were observed using a microscopic cell viability assay. The results suggest that at low frequencies convection plays a statistically significant role in distributing more conductive fluid throughout the tissue, making subsequent pulses more efficacious. The key practical implication is that PEF pretreatment at low frequency can increase the rate of tissue permeabilization in dehydration or extraction processes, and that the treatment will be most effective when cytoplasmic streaming is most active, i.e., with freshly prepared plant tissues.

Effect of pulsed electric field processing on carotenoid extractability of carrot purée

“…() reported a strong correlation between the persistence of cytoplasmic streaming and overall damage to the tissue as a function of frequency in onion tissue. The high net yield of extracted carotenoids after PEF treatment at 5 Hz in the current study might be due to the persistence of cytoplasmic streaming during low PEF frequency, which plays an important role in accelerating the physical damage of cell membranes (Asavasanti et al ., ).…”

“…Therefore, the effect of PEF treatment on carotenoid extractability was compared with the untreated samples from the same batch. There is a critical frequency of ~1 Hz below which permeabilisation of onion tissue was reported to be significantly increased (Asavasanti et al ., ). These authors reported a correlation between PEF frequency and the subsequent speed of intracellular convective motion, that is, cytoplasmic streaming.…”

The natural history of consciousness, and the question of whether plants are conscious, in relation to the Hameroff-Penrose quantum-physical ‘Orch OR’ theory of universal consciousness

“…In a recent study where a 50Hz oscillating electrical field was imposed on plant tissue, permeabilisation of the tissue was brought about in a manner dependent upon the presence of actin, suggesting that actin fila ment oscillation and/or cytoplasmic streaming may be allow the opening of the plasma membrane, 203 which possibly may allow the initiation of APs.…”

Use of Pulsed Electric Fields to Induce Breakage of Glandular Trichome Cells in Leaves of Fresh Patchouli (Pogostemon cablin Benth.): Specific Energy Input Consumption

“…PEF treatment at a low frequency can increase the rate of tissue permeabilization. 20 At low frequencies, the GT cell membrane acts as a capacitor to prevent the flow of electrical current into the intracellular medium. After increasing the frequency, the cell membrane becomes less and less resistant to current flow.…”