Microwave radiation alters burn injury-evoked electric potential in Nicotiana benthamiana.

The dielectric effect enforced on charged ions and dipolar molecules by the oscillating electric field of microwaves may influence electric signaling in plants. In the present study, the exposure of Nicotiana benthamiana plants to continuous wave 2.45 GHz microwave radiation with 1.9 - 2.1 W m-2 power density significantly reduced the amplitude of leaf burning-induced variation potential along the plant stem. The change in amplitude of the variation potential occurred mainly because of a significant reduction of the depolarization rate. This effect was not observed during the post-microwave exposure period. The unique characteristics observed in the variation potentials were also observed under microwave exposure, suggesting unaffected information delivery to distant locations or unaffected transport of specific chemicals generated by the injury.

Effects of water turbulence on variations in cell ultrastructure and metabolism of amino acids in the submersed macrophyte, Elodea nuttallii (Planch.) H. St. John.

The interactions between macrophytes and water movement are not yet fully understood, and the causes responsible for the metabolic and ultrastructural variations in plant cells as a consequence of turbulence are largely unknown. In the present study, growth, metabolism and ultrastructural changes were evaluated in the aquatic macrophyte Elodea nuttallii, after exposure to turbulence for 30 days. The turbulence was generated with a vertically oscillating horizontal grid. The turbulence reduced plant growth, plasmolysed leaf cells and strengthened cell walls, and plants exposed to turbulence accumulated starch granules in stem chloroplasts. The size of the starch granules increased with the magnitude of the turbulence. Using capillary electrophoresis-mass spectrometry (CE-MS), analysis of the metabolome found metabolite accumulation in response to the turbulence. Asparagine was the dominant amino acid that was concentrated in stressed plants, and organic acids such as citrate, ascorbate, oxalate and γ-amino butyric acid (GABA) also accumulated in response to turbulence. These results indicate that turbulence caused severe stress that affected plant growth, cell ultrastructure and some metabolic functions of E. nuttallii. Our findings offer insights to explain the effects of water movement on the functions of aquatic plants.

A novel cryoprotective protein (CRP) with high activity from the ice-nucleating bacterium, Pantoea agglomerans IFO12686.

The ice-nucleating bacterium, Pantoea agglomerans IFO12686, induces the cryoprotective protein (CRP) by cold acclimation at 12 degrees C. The CRP was purified to apparent homogeneity by various chromatographies. We found that the purified CRP was a monomer of approximately 29,000 according to gel filtration chromatography and SDS-PAGE, and was a heat-stable protein. The CRP could protect freeze-labile enzymes, lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH) and isocitrate dehydrogenase (iCDH), against freezing-thawing denaturation. The activity of the CRP was about 3.5 x 10(4) times more effective than bovine serum albumin (BSA) and 2 x 10(6) times than COR26 from the ice-nucleating bacterium Pseudomonas fluorescens KUIN-1. We confirmed that the CRP was a novel protein, as judged by the a different molecule mass from the already-known cryoprotectants, and has an extremely high cryoprotective activity.