The absence of fungal or viral diseases of some invasive alien plants partially explains their success. However, for several species this issue has not been studied and no account of such infections are recorded for Impatiens glandulifera, a problematic weed in moist and half-open habitats of central and western Europe. We record for the first time viral infections in plants from different European regions grown in a common garden experiment. The infection was systemic and could be transferred to two species of Chenopodium and five species of Nicotiana, and resulted in the development of local necrotic spots within a week. The symptoms resembled Tobacco Rattle Virus, but this was not confirmed by an ELISA-test. In I. glandulifera the virus led to reduced above-ground biomass. Relative stem biomass and basal diameter were also lower in diseased plants, but therewas no significant differences in plant height and number of main branches. Also virus infection did not affect the following reproductive traits: time to flowering, pollen viability, fruit abortion, seed/ovule ratio, seed number per fruit and individual seed mass. This virus was not transmitted via seed. The potential effects of such viral infections on the population dynamics and biological control of this alien plant are discussed.
Both prostaglandins (PGs) and vitamin E are known to deeply affect immune responses. It is shown here that they both influence T cell-mediated immunity through reciprocal interference on the expression of cyclic-AMP responsive element binding (CREB) family proteins. CREB1 protein of human T lymphocytes was significantly modulated by a brief treatment of 5 to 10 min with PGE2. On the contrary, vitamin E appeared to be ineffective on the CREB1 behavior, while it abolished the PGE2-induced modulation of this protein. The CREB2 protein expression was also affected by PGE2 treatment, but a longer period of incubation (>20 min) was needed to observe these changes. Vitamin E showed a strong enhancing effect on CREB2 that was partially reversed by the subsequent treatment with PGE2. Our results support the idea that there is reciprocal interference between PGE2 and vitamin E on PGE2-induced signals in T lymphocytes. These data are in agreement with the reports concerning different cell systems and experimental conditions., A. Valenti, I. Venza, M. Venza, V. Fimiani, D. Teti., and Obsahuje bibliografii
The skeletal muscles of animals and humans with type 2 diabetes have decreased oxidative capacity. Aerobic exercise can improve muscle oxidative capacity, but no data are available on the amount of exercise required. We investigated the effects of voluntary running exercise and running distance on the skeletal muscle properties of nonobese rats with type 2 diabetes. Six-week-old male diabetic Goto-Kakizaki rats were divided into nonexercised (GK) and exercised (GK-Ex) groups. The rats in the GK-Ex group were permitted voluntary running exercise on wheels for 6 weeks. Age-matched male Wistar rats (WR) were used as nondiabetic controls. Fasting blood glucose and HbA1c levels were higher in the GK and GK-Ex groups than in the WR group and lower in the GK-Ex group than in the GK group. Succinate dehydrogenase (SDH) activity and peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) mRNA levels in the soleus and plantaris muscles were higher in the WR and GK-Ex groups than in the GK group. HbA1c and total cholesterol levels were negatively correlated with running distance and SDH activity and Pgc-1α mRNA levels in the soleus muscle were positively correlated with running distance. The onset and progression of diabetes in nonobese diabetic rats were effectively inhibited by running longer distances.
Two cultivars of common buckwheat (Fagopyrum esculentum), Pyra and Siva, were exposed to three treatments: water deficit (WD), foliar spraying by selenium (as Na2SeO4) (Se), and the combination of both. In WD-plants the stomatal conductance (gs) was significantly lower, while WD+Se-plants of Siva had significantly higher gs. None of the treatments resulted in significant differences of potential photochemical efficiency of photosystem 2 (PS2). A significantly higher actual photochemical efficiency of PS2 was obtained in Siva WD-plants and in Pyra Se-and WD-plants which was possibly due to improvement of plant water management during treatment. A significant interaction was observed between the effects of WD and Se on respiratory potential in Pyra. WD, Se, and the WD+Se combination resulted in shorter Pyra and Siva plants, with a reduced number of nodes. WD slightly negatively affected the yield per plant. The yield was highest in plants exposed to Se only. In Siva the number of seeds was triple while the average seed mass remained unchanged. and N. Tadina ... [et al.].
Osmotic adjustment, accumulation of soluble saccharides, and photosynthetic gas exchange were studied in five durum wheat (Triticum turgidum L. var. durum) and one wild emmer wheat (Triticum turgidum L. var. dicoccoïdes) cultivars of contrasting drought tolerance and yield stability. Soil water contents (SWC) were 100, 31, 20, and 12 % of maximum capillary capacity. Under mild water stress (SWC 31 to 20 %), osmotic adjustment capacity and high accumulation of saccharides were found in cv. Cham1, a high yielding and drought tolerant cultivar, and in var. dicoccoïdes, while lowest values were noted in the durum wheat landraces Oued-Zenati and Jennah-Khotifa. Under more severe water stress (SWC 12 %), the cv. Cham1 maintained higher net photosynthetic rate (PN) than other genotypes. The observed changes in the ratio intercellular/ambient CO2 concentration (ci/ca) indicated that under mild and severe water stress, the decrease in PN was mainly due to stomatal and non-stomatal factors, respectively. and D. Rekika ... [et al.].
Bothriochloa ischaemum L. is an important species in many temperate regions, but information about the interactive effects of water stress and fertilization on its photosynthetic characteristics was inadequate. A pot experiment was conducted to investigate the effects of three water [80% (HW), 40% (MW), and 20% (LW) of field capacity (FC)] and four fertilization regimes [nitrogen (N), phosphorus (P), nitrogen with phosphorus (NP), and no fertilization] on leaf photosynthesis. Leaf gas exchange and photosynthetic light-response curves were measured at the flowering phase of B. ischaemum. Water stress decreased not only the leaf gas-exchange parameters, such as net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), and water-use efficiency (WUE) of B. ischaemum, but also downregulated
PN-photosynthetically active radiation (PAR) curve parameters, such as light-saturated net photosynthetic rate (PNmax), apparent quantum efficiency (AQE), and light compensation point (LCP). Fertilization (N, P, and NP) enhanced the daily mean PN values and PNmax under the HW regime. Addition of N (either alone or with P) improved the photosynthetic capacity of B. ischaemum under the MW and LW regimes by increasing PN, PNmax, and AQE and reducing dark respiration rate and LCP, but the addition of P alone did not significantly improve the photosynthetic performance. Decline in PN under each fertilization regime occurred during the day and it was caused mainly by nonstomatal limitation. Our results indicated that water was the primary limiting factor for photosynthesis in B. ischaemum, and that appropriate levels of N fertilization improved its potential photosynthetic capacity under water-deficit conditions. and W. Z. Xu, X. P. Deng, B. C. Xu.
Wheat plants grown in controlled growth chambers were exposed to drought stress (DS) and high temperature (HT) singly and in combination (DS+HT). The effects of these two stresses on net photosynthetic rate (PN), stomatal conductance (gs), intercellular CO2 concentration (Ci), quantum efficiency of photosystem 2 (ΦPS2), variable to maximum chlorophyll (Chl) fluorescence (Fv/Fm), photochemical (qp) and non-photochemical (NPQ) Chl fluorescence, and yield were investigated. Grain yield was decreased by 21 % due to DS, while it was increased by 26 % due to HT. PN, g s, Ci, and Chl fluorescence were dramatically reduced to DS, HT, and their interaction, except NPQ which showed an increase due to HT.
Effects of high-temperature stress (HTS) and PEG-induced water stress (WS), applied separately or in combination, on the functional activity and ultrastructure of the photosynthetic apparatus (PSA) of maize (Zea mays L.) and sunflower (Helianthus annuus L.) plants were investigated. In maize plant tissues WS provoked the decrease in RWC by 10.9 %, HTS by 7.0 %, and after simultaneous application of the both treatments the decrease was 32.7 % in comparison with control plants. Similar but more expressed changes were observed in sunflower plants. Sunflower was more sensitive to these stresses. Net photosynthetic rate decreased significantly after all treatments, more in sunflower. In mesophyll chloroplasts after separately applied WS and HTS the number of grana and thylakoids was reduced and electron-transparent spaces appeared. At combined stress (WS+HTS) granal and stromal thylakoids were considerably affected and chloroplast envelope in many of them was partially disrupted. and I. Dekov, T. Tsonev, I. Yordanov.
Two-month-old seedlings of Sophora davidii were subjected to a randomized complete block design with three water (80, 40, and 20 % of water field capacity, i.e. FC80, FC40, and FC20) and three N supply [N0: 0, Nl: 92 and Nh: 184 mg(N) kg-1(soil)] regimes. Water stress produced decreased leaf area (LA) and photosynthetic pigment contents, inhibited photosynthetic efficiency, and induced photodamage in photosystem 2 (PS2), but increased specific leaf area (SLA). The decreased net photosynthetic rate (PN) under medium water stress (FC40) compared to control (FC80) might result from stomatal limitations, but the decreased PN under severe water deficit (FC20) might be attributed to non-stomatal limitations. On the other hand, N supply could improve photosynthetic capacity by increasing LA and photosynthetic pigment contents, and enhancing photosynthetic efficiency under water deficit. Moreover, N supply did a little in alleviating photodamages to PS2 caused by water stress. Hence water stress was the primary limitation in photosynthetic processes of S. davidii seedlings, while the photosynthetic characters of seedlings exhibited positive responses to N supply. Appropriate N supply is recommended to improve photosynthetic efficiency and alleviate photodamage under water stress. and F. Z. Wu ... [et al.].
a1_Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V1) and moderate water stress (V2) imposed at one of four cotton growth stages [i.e., S1 (from the full budding to early flowering stage), S2 (from early flowering to full flowering), S3 (from full flowering to full bolling), and S4 (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70-75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S2V2 treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S1V1, the root activity in the 20-100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S1V1 showed no significant effect on the yield but it increased total WUE and irrigation WUE., a2_These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas., H. H. Luo, Y. L. Zhang, W. F. Zhang., and Obsahuje seznam literatury