Photosynthetic and growth characteristics of the control potato plants cv. Zvíkov and those transformed by Agrobacterium were compared during their cultivation in vitro in agar medium with 1 % saccharose, after having been transplanted into pots with soil, or growing from tubers in soil. The average leaf aiea, fresh and dry matter, chlorophyll a and b ratio, and contents calculated per fresh and diy matter of the leaf area were significantly higher in the control plants raised from tubers and in vitro cultivated than in the transplanted ones. The significant increase in oxygen evolution by leaf fragments was found only in the control potato plants raised from tubers. Differences between photochemical activities of chloroplasts isolated from control and transformed plants were statistically significant only when calculated per fresh leaf matter. Chloroplasts from transformed potato plants grown from tubers and from those cultivated in vitro exhibited higher activities of photosystems (PS) 2 and PS 1 independently on the donors and acceptors of electrons ušed. On the contrary, higher activities of both photosystems were found in chloroplasts isolated from the control plants transferred to soil.
The review deals with photosynthetic H2 production by various organisms, paying a speciál attention to eukaryotes, It includes a generál characterization of the catalyzing enzymes (hydrogenase and nitrogenase), quantum efficiency, the kinetics and mechanism of H2 photoevolution, the distribution and activity of H2 photoproducers (33 genera of eukaryotes), physiological functions of this process as well as recent developments in photobiological hydrogen technology.
Effect of temporary drought on the photosynthetic characteristics, the photosynthetic nutrient-use efficiency (PNUE, PPUE), the water-use efficiency (WUE), acetylene reduction nodule activity (ARA) and the solute accumulation has been examined in nodulated alfalfa plants. The plants were subjected to moderate or severe cycles of drought (drought-recovery). Growth decreased markedly imder the water deficit, but no significant differences were found between either level of drought. As stress progressed, the plants developed higher root/shoot ratios than Controls. ARA declined progressively during water deficit treatments and upon rewatering no recovery was observed. PNUE and PPUE markedly decreased, whereas WUE increaseď in drought treated plants. Proline and inorganic cations (K, Ca, Mg) concentrations were always higher in drought-stressed plants, but sugar (TSS) content increased only in roots and nodules. Hence, imder cyclic drought nodulated alfalfa plants adjusted osmotically and achieved an improved WUE, which suggested an enhanced drought tolerance.
Photosynthetic pathway type, based on 5*^C measurements, was determined for 48 species in 39 genera and 15 families of flowering plants from the grassiand region of Northeast China. Of this total, 10 species in 10 genera from 4 families were found to háve C4 photosynthesis; 38 species in 29 genera from 13 families had C3 photosynthesis. One C4 species in the Chenopodiaceae and three in the Gramineae had not been previously docnmented in the literatuře. The C4 species were most frequent in disturbed habitats, meadow steppe and šalině grassiand; C3 species dominated the other habitats sampled.
Maximum values of chlorophyll (Chl) (a + b) content, potentíal (Pp) and net (Pu) photosynthetíc rate in the populatíon of 25 species growing in the tundra of Wrangel Island are presented. Field measurements of response of Pp and P^ to irradiance were doně. Maximum Chl content in arctic plants was typically low [O.S-2.9 g kg'i(f.m.)] and rather close to tíie range characterizing extreme biomes: i.e. deserts and high mountains. By contrast, the sum of carotenoids (Car) was hi^ [1.1-2.3 g kg-i(d.m.)]. In most tundra plants the ratío Chl/Car varied firom 4 to 5. Lower values of Chl/Car were observed only in the high mountain plants of the Paniirs. The peculiarity of pigment apparatus organization in arctic species was expressed in low values of the ratío of pigment-protein complexes LHC/CPl + CP2 dut was mostly close to 1 or lower, as well as in the smáli size of photosynthetíc unit which was 100-200 molecules. Irradiance response of photosynthesis, pigments and structure characteristics indicated features usually considered typical bodi of sun and shade tolerant plants. Their high ability to adapt both to low and high irradiance at low temperature is a substantíal guarantee for 24-h photosyndiesis during polar day.
The effects of moisture stress on leaf water potential ('ť|eaf)> photosynthetic rate (/^n) and stomatal resistance (r^) of cotton, Gossypium hirsutum L., were studied under field conditions. Sprinkler irrigation trials were conducted using the single source line technique. r^ increased and decreased as a result of moisture stress, more than in a concurrent drip irrigation experiment, r^ was only slightly affected by irradiance when the plants were subjected to moisture stress, but it decreased in response to an increase in irradiance (/) in the well irrigated plants. A linear relationship between T^ieaf and r^ and between 'ťigaf and found in both experiments at low /, whereas exponential relationship was found at high I. Even though high values of r^ were recorded under the extreme moisture stresses of both experiments, intemal CO2 concentration (cj) increased during the day, indicating that non-stomatal factors (such as mesophyll resistance) are the main factors limiting the photosynthetic process.
Peanut plants were adapted to drought. Due to parahelionastic leaf movements under water stress they decreased heat load and transpiring area, Folding of leaflets minimised damage to photosynthetic apparatus by high temperatoe. A positive correlation between transpiration rate (E) and leaf water potential indicated the dependence of the latter on E. Phosphoenolpyruvate carboxylase (PEPC) activity progressively increased with increased period of stress, whereas activities of ribulose-l,5-bisphosphate carboxylase (RuBPC) and NADP-glyceraldehyde-3- phosphate dehydrogenase (NADP-G-3-PDH) decreased gradually.
Photosynthetic characteristics of seedling leaves and mesophyll protoplasts in Lolium species were assessed to search possibility for improvement of two cultivated species, L. pereme and L. mulíiflorum. Smáli size of mesophyll protoplasts was a suitable trait for estimating photosynthetic characteristics, when combined with high photosynthetic rate (Fn) P^r protoplast. L. rigidum and L. suhlatum háve more potential for improvement of because of higher per unit leaf aiea and per chlorophyll (Chl) and higher rate of Chl content: surface area of protoplast, than L. pereme and L. multiflorum.
Photosystem 2 (PS 2) reaction centers inactive in plastoquinone pool reduction are present in isolated thylakoid membranes, intact chloroplasts, and leaves of dark- adapted plants. Here we describe om recent work investigating the physical and physiological properties that distínguish inactive firom active centers. Inactive PS 2 centers are defíned by their slow rate of Q^’ oxidation. They háve a competent water oxidation systém and constitute about one-third of the total PS 2 present in dark- adapted leaves and thylakoid membranes. Their effective absorption cross section for radiant energy utilization is half that of active PS 2 centers. Irradiation modifies inactive PS 2 centers in leaves and thylakoid membranes. The modification is manifested by a 50 % dechne of their varíable fluorescence and of their contribution to the electrochromic shift. In leaves the light-induced modification is reversible in the dark, whereas it is irreversible in thylakoid membranes.
Phylogenetic relationships within the suborder Trypanosomatina were inferred from the kinetoplast DNA minicircle conserved region sequences. Trees built using distancc-matrix (Neighbor-Joining) and maximum parsimony methods showed that the minicircle conserved regions (CRs) provide a sensitive and specific molecular marker suitable for phylogenetic analyses of subspecies and strains of trypanosomalid flagellates, as testified by the subdivision of the genus Leishmania into the subgenera Leishmania, Viannia and Sauroleishmania. However, since Phytomonas and monogenetic parasites of insects represent the earliest diverging groups, the CRs do not seem to be useful for inference of relationships among major lineages of the order Kinetoplastida.