Growth characteristics of mung beans and water convolvuluses exposed to 425-MHz electromagnetic fields.

Effects of high-frequency, continuous wave (CW) electromagnetic fields on mung beans (Vigna radiata L.) and water convolvuluses (Ipomoea aquatica Forssk.) were studied at different growth stages (pre-sown seed and early seedling). Specifically, the effects of the electromagnetic source's power and duration (defined as power-duration level) on the growth of the two species were studied. Mung beans and water convolvuluses were exposed to electromagnetic fields inside a specially designed chamber for optimum field absorption, and the responses of the seeds to a constant frequency at various power levels and durations of exposure were monitored. The frequency used in the experiments was 425 MHz, the field strengths were 1 mW, 100 mW, and 10 W, and the exposure durations were 1, 2, and 4 h. Results show that germination enhancement is optimum for the mung beans at 100 mW/1 h power-duration level, while for water convolvuluses the optimum germination power-duration level was 1 mW/2 h. When both seed types were exposed at the early sprouting phase with their respective optimum power-duration levels for optimum seed growth, water convolvuluses showed growth enhancement while mung bean sprouts showed no effects. Water content analysis of the seeds suggests thermal effects only at higher field strength.

Evaluation of photo-induced cellular damage using photoautotrophic cultures of puk-bung hairy roots as a sensing tool.

In photoautotrophic cultures of pak-bung hairy roots, strong light irradiation (22 W/m(2)) increased the content of reactive oxygen species (ROS) in the cells, resulting in chlorophyll (Chl) degradation and DNA injury. The Chl degradation rate, R(D), can be used as a parameter to measure the cellular damage caused by photo-induced stress. The presence of the antioxidants ascorbic acid, chlorogenic acid or catechin reduced the R(D), while lowering the content of ROS and moderating the DNA injury.

Environmental regulation of floral anthocyanin synthesis in Ipomoea purpurea.

Responses of metabolites to environmental fluctuations may play large roles in biological adaptation, yet how these responses initiate in the natural environment and the molecular mechanisms remain unclear. Synthesis of floral anthocyanins, as typical examples of secondary metabolites, is known to respond to the physical environment and therefore an ideal system for understanding the process of the environmental regulation. Here, by simultaneous monitoring of six natural environmental variables and anthocyanin content of daily opening flowers throughout a natural flowering season ( approximately 50 days) of Ipomoea purpurea, we have identified significant and positive correlations of temperature (3-days ago) and ultraviolet (UV) light intensity (5-days ago) with the floral anthocyanin content. We sequenced all known (seven structural and three regulatory) anthocyanin genes in I. purpurea flowers and examined their transcript quantities in the natural environment across eight floral developmental stages (covering 0-96 h before anthesis). The anthocyanin gene expression patterns corroborated with the inferred effects from the time-series data, and further showed that the positive UV effect became negative on transcript levels about 36 h before anthesis. With falling natural temperature, content of the principal anthocyanin declined, whereas that of an alternative anthocyanin with fewer glucose and caffeic acid moieties increased. Our data suggest that environmental regulation of the anthocyanin pathway may account for more than half of the flux variation in the floral limb, and is influenced mainly by daily average temperature and UV light intensity that modulate anthocyanin transcript levels (most likely via myb1) at floral developmental stages.