Clonal growth is of great importance for survival, growth, expansion, and resource utilization of some species. Knowing how clonal plants respond morphologically and physiologically to different light environments can be useful to explain their occurrence and abundance patterns under specific environmental conditions. Responses of clonal growth, leaf gas exchange, fluorescence emission, and photosynthetic pigment concentrations to different light environments (100, 60, 30, and 15%) were studied in Amomum villosum, grown in the traditional way for economic purpose in Xishuangbanna, southwest China. The results showed that A. villosum attained vigorous clonal growth under 30% and 60% light, with a higher plant height, number of ramets, stolon length, thicker stems and stolons. Shade-grown A. villosum possessed a larger leaf area than that of the sun-grown plants in order to capture more light. For A. villosum, the higher
light-saturated net photosynthetic rate, light-saturation point, larger fresh and dry biomass can explained the better clonal growth for A. villosum under 30% and 60% light. Amomum villosum attained the highest values of minimal chlorophyll fluorescence under 100% light and the lowest values of maximum photochemical efficiency of PSII under 15% light. Our findings indicated that the full irradiance was too strong and 15% light was too weak for A. villosum plants. It was also verified by higher concentrations of photosynthetic pigments in the shaded plants compared to those grown under full sun light. Our results suggested that A. villosum seemed to be adapted to moderate light environment (60-30%) which was indicated by vigorous clonal growth and higher photosynthesis. This information is very useful to select clonal species for rainforest or understory projects. The cultivation of A. villosum in rainforest should not be done under too strong (100%) or too weak light environment (less than 15%)., Y. H. Guo, C. Yuan, L. Tang, J. M. Peng, K. L. Zhang, G. Li, X. J. Ma., and Seznam literatury
Ramie (Boehmeria nivea L.) is an important crop that serves as fine fiber material, high protein feedstuff, and valuable herbal medicine in China. However, increasing salinity in soil limits the productivity. We investigated in a greenhouse experiment responses to salinity in two ramie cultivars, Chuanzhu-12 (salt-tolerant cultivar, ST) and Xiangzhu-2 (salt-sensitive cultivar, SS), to elucidate the salt tolerance mechanism of this species. Salinity stress substantially reduced both chlorophyll and carotenoid contents. In addition, net photosynthesis, transpiration rate, stomatal conductance, intercellular CO2 concentration, and the ratio of intercellular CO2 to ambient CO2 were affected, less in ST. Nevertheless, salinity stress markedly improved water use efficiency and intrinsic water use efficiency in both species. Moreover, relative water contents, soluble proteins, and catalase activity were substantially impaired, while proline accumulation and superoxide dismutase activity were enhanced substantially, more in ST. Furthermore, noteworthy increase in peroxidase activity and decrease in malondialdehyde content was recorded in ST, whereas, in SS, these attributes changed conversely. Overall, the cultivar ST exhibited salt tolerance due to its higher photosynthetic capacity, chlorophyll content, antioxidative enzyme activity, and nonenzymatic antioxidants, as well as reduced lipid peroxidation and maintenance of the tissue water content. This revealed the salt tolerance mechanism of ramie plants for adaptation to salt affected soil., C.-J. Huang, G. Wei, Y.-C. Jie , J.-J. Xu, S.-Y. Zhao, L.-C. Wang, S. A. Anjum., and Obsahuje seznam literatury
In order to test the effects of irrigation depth on winter wheat photosynthesis, four treatments were applied in a field experiment using PVC growth tubes (identical amounts of water were applied on the land surface, and at 60, 75, and 90% of the depth for the winter wheat root distribution, denoted as D0, D60, D75, and D90, respectively). Compared to the surface irrigation treatment D0, the leaf area index, chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance, and intercellular CO2 concentration increased with irrigation depths. The values of these indicators obtained by the underground irrigation treatment D75 were higher than those of D60 and D90, and thus D75 was found to be the optimum irrigation depth. Furthermore, a positive but not significant correlation (r = 0.62) between carbon isotope discrimination (Δ13C) and grain yield was found. This study improves our understanding of the mechanism of underground water distribution control with depth, and the efficiency of
water-saving irrigation for winter wheat., L. J. Zheng, J. J. Ma, X. H. Sun, X. H. Guo, J. Jiang, R. Ren, X. L. Zhang., and Obsahuje bibliografii
The widespread Mediterranean Pinus pinea showed exceptionally low genetic diversity and low differentiation between traits in the adult phase. We explored the adaptation potential of seedlings from four main Iberian provenances during their regeneration phase. We assessed the variability of shoot growth, allometry, physiological traits, and phenotypic plasticity to the interactive effect of light and water environments during 8-month moderate water-stress cycle and after one-week heat wave. The effect of shade and drought was mainly orthogonal whatever the provenance. The inland La Mancha provenance showed higher shoot growth and biomass compared to the southern coastal Depresión-del-Guadalquivir provenance. Following the heat wave, La Mancha presented higher net photosynthetic rates, a lower decrease in maximal quantum efficiency of PSII, and a higher accumulated relative height growth, thus, showing an adaptive advantage. The observed differences corroborated the ecological grouping of the provenances along latitudinal and inland-coastal gradients. We confirmed the high adaptive plasticity of Pinus pinea to the unpredictable Mediterranean environment., M. Pardos, R. Calama., and Obsahuje bibliografii
The responses of photosynthesis and growth to increasing CO2 concentration ([CO2]) were investigated in Hippophae gyantsensis and H. rhamnoides subsp. yunnanensis, which are endemic at the Qinghai-Tibet Plateau and phylogenetically related, but distributed parapatrically in divergent regions. Seedlings of the two species were grown at ambient [AC; 360 μmol(CO2) mol-1] and elevated [EC; 720 μmol(CO2) mol-1] [CO2] in growth chambers. The responses to EC were significantly different between the two species. EC induced an increase in photosynthesis, stomatal conductance, intrinsic water-use efficiency, apparent quantum efficiency, total dry mass, and a decrease in photorespiration rate, maximum carboxylation rate of Rubisco, and maximum electron transport rate in H. gyantsensis compared to those in H. rhamnoides subsp. yunnanensis. Moreover, a significant increase in leaf nitrogen content and a decrease in root/shoot ratio was also observed in H. gyantsensis. H. gyantsensis showed a significantly higher specific leaf area than that of H. rhamnoides through treatments. Relative to H. rhamnoides subsp. yunnanensis, H. gyantsensis showed a greater potential to increase photosynthesis and growth to cope with the increasing [CO2] and it might expand its distribution range in the future., F. Ma, T. T. Xu, M. F. Ji, C. M. Zhao., and Obsahuje seznam literatury
In the field, supplemental application of N fertilizer to rice (Oryza sativa) shortly before the beginning of heading stage increases leaf N content and enhances photosynthesis during the grain-filling period. In search of varietal differences in leaf gas exchange in response to supplemental N application, we examined 13 rice varieties grown in the field during two successive years. The varieties included japonica and indica varieties, both of which are widely grown in Japan. The response to supplemental N application could not be separated clearly between variety groups; some of the japonica varieties, but none of the indica varieties, exhibited significant increase in stomatal conductance (gs) after supplemental N application. Supplemental N was more effective to increase stomatal aperture in the varieties with inherently lower gs. Varieties that showed greater response of g s to supplemental N application might be able to adjust their stomatal aperture with appropriate N control. Although the internal-to-ambient CO2 mole fraction ratio and the leaf carbon isotopic composition (δ13C) differed among varieties as a result of variations in stomatal aperture and the CO2 requirement of mesophyll, supplemental N application barely influenced these parameters, because it only moderately affected stomatal aperture. Since δ13C tended to increase with increasing number of days from transplantation to heading stage in japonica varieties, δ13C values were more sensitive to differences in growth rate between years than to N application., S. Shimoda, A. Maruyama., and Obsahuje bibliografii
RNA editing is post-transcriptional modification to RNA molecules. In plants, RNA editing primarily occurs to two energy-producing organelles: plastids and mitochondria. Organelle RNA editing is often viewed as a mechanism of correction to compensate for defects or mutations in haploid organelle genomes. A common type of organelle RNA editing is deamination from cytidine to uridine. Cytidine-to-uridine plastid RNA editing is carried out by the RNA editing complex which consists of at least four types of proteins: pentatricopeptide repeat proteins, RNA editing interacting proteins/multiple organellar RNA editing factors, organelle RNA recognition motif proteins, and organelle zinc-finger proteins. The four types of RNA editing factors work together to carry out RNA editing site recognition, zinc cofactor binding, and cytidine-to-uridine deamination. In addition, three other types of proteins have been found to be important for plastid RNA editing. These additional proteins may play a regulatory or stabilizing role in the RNA editing complex., Y. Lu., and Obsahuje bibliografické odkazy
The aim of this study was to assess the impact of the mitochondrial alternative oxidase (AOX) pathway on energy metabolism in chloroplasts, and evaluate the importance of the AOX in alleviating drought-induced photoinhibition in pepper (Capsicum annuum L.). Inhibition of AOX pathway decreased photosynthesis and increased thermal energy dissipation in plants under normal conditions. It indicated that AOX pathway could influence chloroplast energy metabolism. Drought reduced carbon assimilation. Photoinhibition was caused by excess of absorbed light energy in spite of the increase of thermal energy dissipation and cyclic electron flow around PSI (CEF-PSI). Upregulation of AOX pathway in leaves experiencing drought would play a critical role in protection against photoinhibition by optimization of carbon assimilation and PSII function, which would avoid over-reduction of photosynthetic electron transport chain. However, inhibition of AOX pathway could be compensated by increasing the thermal energy dissipation and CEF-PSI under drought stress, and the compensation of CEF-PSI was especially significant., W. H. Hu, X. H. Yan, Y. He, X. L. Ye., and Obsahuje bibliografii
The present work showed that spider mite-infested leaves placed in the light were more attractive to predatory mites than the infested leaves placed in the dark; furthermore, an increase in the light intensity enhanced this attractiveness. However, the increase of the light intensity did not change the attractiveness of the uninfested leaves to predatory mites. The capacity of cyanide-resistant respiration and the photosynthetic rates of both the infested and uninfested leaves increased with increasing light intensities, whereas the photosystem (PS) II chlorophyll (Chl) fluorescence decreased. The increase of the capacity of cyanide-resistant respiration in the infested leaves was more dramatic than that in the uninfested leaves, whereas the values of photosynthetic rates and Chl fluorescence were lower in the infested leaves than those in the uninfested leaves. Treatment of the infested and uninfested leaves with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of cyanide-resistant respiration) decreased photosynthetic rates and caused further reductions in PSII fluorescence, especially under a higher light intensity. In contrast, the effects of SHAM on PSII fluorescence parameters and photosynthetic rates of the infested leaves were more dramatic than on those of the uninfested leaves. The treatment with SHAM did not significantly change the attractiveness of the infested or uninfested leaves to the predatory mites under all of the light intensities tested. These results indicated that cyanide-resistant respiration was not directly associated with the light-induced attraction of predators to plants, but it could play a role in the protection of photosynthesis. Such role might become relatively more important when photosynthesis is impaired by herbivores infestation. and H. Q. Feng ... [et al.].