Response of non-structural carbohydrate content of belowground parts in Equisetum arvense according to the irradiance change during a growing season.

Effects of shading on the growth of Equisetum arvense during the growing season were studied in terms of the dynamics of non-structural carbohydrates (starch, sucrose, glucose). Tubers of 0.04 g dry mass were planted in pots. Plants were cultivated under different radiation conditions (100%, 3%, 100%-->3%, and 100%-->3%-->100%). The carbohydrate concentration in belowground parts responded sharply to the irradiance conditions. Under 3% relative photon flux density (PFD), they could not grow beyond the initial mass and decayed. Dry mass per length of rhizomes was highly correlated with the starch concentration, which was correlated with the mass of current tubers. The rhizomes of low starch concentration did not form current tubers. The carbohydrate concentration of rhizomes increased when the plants were transferred from 3% relative PFD to 100% irradiance conditions. After ca. 2 months of improved PFD, they had the same content of non-structural carbohydrates as the 100% PFD plants.

[Reactive oxygen forms and luminescence of intact microspore cells]. / Aktivnye formy kisloroda i liuminestsentsiia intaktnykh kletok mikrospor.

The participation of reactive oxygen species (ROS) in luminescence (chemiluminescence and autofluorescence induced by ultraviolet light of 360-380 nm) was analyzed. Microspores, the pollen (male gametophyte) of Hippeastrum hybridum, Philadelphus grandiflorus, and Betula verrucosa and vegetative microspores of the spore-breeding plant Equisetum arvense served as models. It was found that the addition of the chemiluminescent probe lucigenin, which luminesces in the presence of superoxide anionradicals, leads to intensive chemiluminescence of microspores. No emission was observed in the absence of lucigenin and in the presence of the dye luminol as a chemiluminescent probe. The emission decreased significantly if superoxide dismutase, an enzyme of the superoxide anionradical dismutation during which this radical disappeared, was added before the dye addition. The autofluorescence intensity of microspores decreased in the presence of both superoxide dismutase and peroxidase, an enzyme destroying hydrogen peroxide and organic peroxides. The most significant effect was noted after the addition of peroxidase, which indicates a greater contribution of peroxides to this type of emission. The fumigation with ozone, which increases the amount of ROS on the cell surface, enhanced the intensity of the chemiluminescence of microspores with lucigenin, but decreased the intensity of the autofluorescence of microspores. Exogenous peroxides (hydrogen peroxide and tert-butylhydroperoxide) stimulated the autofluorescence of pollen and vegetative spores in a concentration-dependent manner. It was shown that the formation of ROS contributes to the luminescence of plant microspores, which reflects their functional state.