Ultrastructural and antioxidative changes in lupine embryo axes in response to salt stress

Embryo axes of lupine (Lupinus luteus L. 'Mister') were subjected to 0.1 M NaCl salt stress for 24 and 48 h. The ultrastructure modification and adjustment of antioxidant enzymes activities and izoenzymes profiles were observed. In cells of lupine embryo axes grown for 48 hours in medium with 0.1 M NaCl mitochondria took the forked shape and bulges of the outer mitochondrial membranes appeared. Moreover, the inflating and swelling of rough endoplasmic reticulum (RER) lumen and fragmentation of RER were noticed. The level of H2O2 was higher in salt treated embryo axes after 24 hours and increase of thiobarbituric acid reactive substances was observed after both 24 and 48 h of salt treatment. Native gel electrophoresis showed increased intensities of bands for catalase isozymes in response to salt stress, whereas activity of catalase was higher only in embryo axes grown for 48 h in control conditions. Appearance of two new isoforms of ascorbate peroxidase was observed after 48 h only under control condition, however increased activities were stated for both control and salt-stress condition after 48 h. No changes in isozymes pattern for superoxide dismutase were observed, but significant decrease in superoxide dismutase activity was noticed in relation to time and salt stress. Possible role of these enzymes in salt stress tolerance is discussed. The 0.1 M salt stress is regarded as a middle stress for lupine embryo axes and the efficiency of stress prevention mechanisms is proposed

Mathematical and experimental investigation of water migration in plant xylem

Plant can take water from soil up to several metres high. However, the mechanism of how water rises against gravity is still controversially discussed despite a few mechanisms have been proposed. Also, there still lacks of a critical transportation model because of the diversity and complex xylem structure of plants. This paper mainly focuses on the water transport process within xylem and a mathematical model is presented. With a simplified micro channel from xylem structure and the calculation using the model of water migration in xylem, this paper identified the relationship between various forces and water migration velocity. The velocity of water migration within the plant stem is considered as detail as possible using all major forces involved, and a full mathematical model is proposed to calculate and predict the velocity of water migration in plants. Using details of a specific plant, the velocity of water migration in the plant can be calculated, and then compared to the experimental result from Magnetic Resonance Imaging (MRI). The two results match perfectly to each other, indicating the accuracy of the mathematical model, thus the mathematical model should have brighter future in further applications

Ultrastructural and antioxidative changes in lupine embryo axes in response to salt stress

Embryo axes of lupine (Lupinus luteus L. ‘Mister’) were subjected to 0.1 M NaCl salt stress for 24 and 48 h. The ultrastructure modification and adjustment of antioxidant enzymes activities and izoenzymes profiles were observed. In cells of lupine embryo axes grown for 48 hours in medium with 0.1 M NaCl mitochondria took the forked shape and bulges of the outer mitochondrial membranes appeared. Moreover, the inflating and swelling of rough endoplasmic reticulum (RER) lumen and fragmentation of RER were noticed. The level of H2O2 was higher in salt treated embryo axes after 24 hours and increase of thiobarbituric acid reactive substances was observed after both 24 and 48 h of salt treatment. Native gel electrophoresis showed increased intensities of bands for catalase isozymes in response to salt stress, whereas activity of catalase was higher only in embryo axes grown for 48 h in control conditions. Appearance of two new isoforms of ascorbate peroxidase was observed after 48 h only under control condition, however increased activities were stated for both control and salt-stress condition after 48 h. No changes in isozymes pattern for superoxide dismutase were observed, but significant decrease in superoxide dismutase activity was noticed in relation to time and salt stress. Possible role of these enzymes in salt stress tolerance is discussed. The 0.1 M salt stress is regarded as a middle stress for lupine embryo axes and the efficiency of stress prevention mechanisms is proposed