Competition plays an important role in the replacement of native species by alien plants. A greenhouse experiment was conducted to investigate whether the competition pattern of alien Robinia pseudoacacia L. and native Quercus acutissima Carr. is affected by soil sterilization. Physiological traits, such as gas-exchange parameters and chlorophyll (Chl) content, and growth traits, such as the biomass accumulation of the two species, were examined in natural soil or in soil sterilized with benomyl. The results show that native Q. acutissima inhibits the growth of R. pseudoacacia in natural soil. When the two plants coexisted and competed under sterilization treatment, R. pseudoacacia was less inhibited by Q. acutissima and the competition of R. pseudoacacia decreased the growth of Q. acutissima in terms of biomass, Chl a, Chl b, total Chl, and Chl a/b. These results suggest that soil sterilization benefits the growth of R. pseudoacacia and changes the competition pattern by the changed soil biota. Soil sterilization increased the biomass of root nodules, which ultimately benefits the growth of R. pseudoacacia and root nodule bacteria may be important in the dispersal and invasion process of nitrogen-fixing alien plants such as R. pseudoacacia., H. Chen ... [et al.]., and Obsahuje bibliografii
Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars.
Arbuscular mycorrhizal fungi (AMF) form symbioses with many plants. Black locust (Robinia pseudoacacia L.) is an important energy tree species that can associate with AMF. We investigated the effects of AMF (Rhizophagus irregularis and Glomus versiforme) on the growth, gas exchange, chlorophyll (Chl) fluorescence, carbon content, and calorific value of black locust seedlings in the greenhouse. The total biomass of the arbuscular mycorrhizal (AM) seedlings was 4 times greater than that of the nonmycorrhizal (NM) seedlings. AMF greatly promoted the photosynthesis of black locust seedlings. AM seedlings had a significantly greater leaf area, higher carboxylation efficiency, Chl content, and net photosynthetic rate (PN) than NM seedlings. AMF also significantly increased the effective photochemical efficiency of PSII and significantly enhanced the carbon content and calorific value of black locust seedlings. Seedlings inoculated with G. versiforme had the largest leaf area and highest biomass, Chl content, PN, and calorific value., X. Q. Zhu, C. Y. Wang, H. Chen, M. Tang., and Obsahuje bibliografii
In this study, we investigated maximal quantum yield of PSII photochemistry(Fv/Fm),effective quantum yield of PSII photochemistry (ΦPSII), and nonphotochemical quenching (NPQ) of walnut (Juglans regia ‘Xinxin2’) leaves with different leaf-to-fruit ratios (LFRs). The results indicated that the increasing LFR increased the values of Fv/Fm, ΦPSII, and NPQ in leaves on the girdled shoot with one and two leaves, and decreased the values of Fv/Fm and ΦPSII in leaves on the girdled shoot with five leaves, whereas had no effect on the chlorophyll (Chl) fluorescence in leaves on the girdled shoot with three and four leaves. These results indicate that the effects of LFR on Chl fluorescence depend on a LFR range and show a transitional trend transition, and that excessive fruit load accelerates leaf senescence resulting in the destruction of the reaction center in PSII., C. F. Zhang, C. D. Pan, H. Chen., and Obsahuje bibliografii
Plant growth, contents of photosynthetic pigments, photosynthetic gas exchange, and chlorophyll (Chl) fluorescence in soybean [Glycine max (L.) Merr. cv. Heinong37] were investigated after it was inoculated with Sinorhizobium fredii USDA191 or treated with 5 mM (NH4)2SO4 (N5) and 30 mM (NH4)2SO4 (N30), respectively. In the plants following N5 fertilization, not only plant biomass, leaf area, and Chl content, but also net photosynthetic rate (PN), stomatal conductance (gs), carboxylation efficiency (CE), maximum photochemical efficiency (Fv/Fm) of photosystem 2 (PS2), and quantum yield of PS2 (ΦPS2) were markedly improved as compared with the control plants. There were also positive effects on plant growth and plant photosynthesis after rhizobia inoculation, but the effects were much less than those of N5 fertilization. For N30 plants there were no significant positive effects on plant growth and photosynthetic capacity. Plant biomass, PN, and gs were similar to those of N-limited (control) plants. ΦPS2 and photochemical quenching (qP) were obviously declined while content of carotenoids and non-photochemical quenching (qN) were significantly enhanced in N30 treated plants. This indicated that excess N supply may cause some negative effects on soybean plants. and X.-J. Zhou ... [et al.].
Poplars (Populus spp.) are widely used in the pulp and paper industry and as bioenergy resources. Poplars require a large amount of water for biomass accumulation and lack of water is a limiting factor for poplar growth. Arbuscular mycorrhizal (AM) fungi have been previously reported to afford some plant species with greater resistance to drought stress. However, the effects of AM fungi on hybrid poplar under drought stress and recovery have not been studied. The main aim of this study was to evaluate the effects of the AM fungus, Rhizophagus irregularis, on the growth, water status, chlorophyll (Chl) content and fluorescence, and photosynthesis of poplar seedlings. The experiment was divided into three stages. At each stage of the experiment, the seedlings were subjected to a different watering regime: well-watered (prior stress), drought, and then rewatering (recovery). Measurements were taken at the end of each stage of the experiment. The results showed that mycorrhizal plants had a higher net photosynthetic rate and Chl fluorescence compared with nonmycorrhizal plants, regardless of the stage. Mycorrhizal and nonmycorrhizal plants showed different responses to drought stress: mycorrhizal plants showed better water-use efficiency and water uptake under drought stress conditions. In general, the poplar seedlings that formed the AM symbiosis with R. irregularis showed enhanced growth and reduced loss of biomass during the drought stress compared with the nonmycorrhizal seedlings., T. Liu, M. Sheng, C. Y. Wang, H. Chen, Z. Li, M. Tang., and Obsahuje bibliografii
We investigated neuronal activity of the medulla oblongata
during gastroesophageal reflux-related cough (GERC). A rat
model of GERC was generated by perfusing HCl into lower
esophagus and inducing cough with citric acid. The HCl group rat
was received HCl perfusion without citric acid-induced cough.
The saline control rat was perfused with saline instead and cough
was induced. Citric acid-induced cough rat was only induced by
citric acid. Blank group rats were fed normally. Fos expressions
were observed in medulla oblongata nuclei using
immunohistochemistry. Manganese-enhanced magnetic
resonance imaging (MEMRI) was performed to detect the
Mn2+ signal following intraperitoneal injection of MnCl2. HCl
perfusion and citric acid-induced cough caused Fos expressions in
the nucleus of solitary tract (nTS), dorsal motor nucleus of the
vagus (DMV), paratrigeminal nucleus (Pa5), and intermediate
reticular nucleus (IRt), which was higher than HCl group, saline
control group, citric acid-induced cough group, and blank group.
A high Mn2+ signal was also observed in most of these nuclei in
model rats, compared with blank group animals. The Mn2+ signal
was also higher in the HCl, saline and citric acid-induced cough
group animals, compared with blank group animals. The study
showed medulla oblongata neurons were excited in a HCl
perfusion and citric acid-induced cough rat model, and nTS, DMV,
Pa5 and IRt neurons maybe involved in the cough process and
signal integrate.
Foliar δ13C values of Calligogum kozlovi and Haloxylon ammodendron ranged from -13.13 to -15.11 ‰, while those of the rest 11 species were in the range of -22.22 to -27.73 ‰. This indicates that two of 13 dominant plant species in the Qaidam Basin possess a C4 photosynthetic pathway. Significant differences were observed for the average foliar δ13C values between C3 or C4 plant communities, between grass and shrub communities, even between the same species derived from different sites. Precipitation accounted for the major part of the differences. and H. Chen ... [et al.].
The main regulatory mechanism of smooth muscle contraction involves Ca2+/calmodulin (CaM)-dependent phosphorylation of myosin (CDPM), by myosin light chain kinase (MLCK). It is also known that the increase in intracellular Ca2+ and phosphorylation of myosin occurs within a short time under physiological conditions, but the muscle tension may persist for a longer period of time. However, the mechanism of this phenomenon is still not clear. We hypothesize that MLCK also phosphorylates myosin in a Ca2+/CaM-independent manner (CIPM). The difference between CIPM and CDPM are as follows. Firstly, the extent of CIPM by MLCK was temperature-independent, whereas CDPM by MLCK was apparently decreasing with increasing temperature. Secondly, in contrast to the decreased extent of CDPM, the prolongation of incubation time did not decrease the extent of CIPM. Thirdly, a high concentration of K＋ influences CIPM less than CDPM. Furthermore, the MLCK inhibitor ML-9 significantly inhibited CDPM by MLCK but not CIPM by MLCK. Lastly, arachidonic acid selectively increased CIPM by MLCK but not CDPM by MLCK. Finally, the activity of Mg2+-ATPase of myosin followed the sequence as this: CDPM > CIPM > unphosphorylated myosin. Our results revealed some primary features of CIPM by MLCK.