a1_Low light availability under a forest canopy often limits plant growth; however, sudden increase in light intensity may induce photoinhibition of photosynthesis. The aim of this study was to evaluate the ecophysiological changes that occur in potted plants of Minquartia guianensis and Swietenia macrophylla during the acclimation process to full sunlight. We used six full-sun independent acclimation periods (30, 60, 90, 120, 150, and 180 days) and a control kept in the shade. Shading was obtained by placing plants under the canopy of a small forest. The Fv/Fm ratio, net photosynthetic rate (PN), the maximum carboxylation velocity of Rubisco (Vcmax), maximum electron transport rate (Jmax), specific leaf area (SLA), and growth were assessed at the end of each of the six acclimation periods. Plant exposure to full sunlight caused a sudden decrease in the Fv/Fm ratio (photoinhibition) particularly in Minquartia. Photooxidation (necrotic patches) of the leaf tissue was observed in upper leaves of Minquartia. The higher PN values were observed in Swietenia under full sun, about 12 μmol(CO2) m-2 s-1. Vcmax25 values were higher after 90 days of acclimation, about 14 μmol(CO2) m-2 s-1 for Minquartia, and 35 μmol(CO2) m-2 s-1 for Swietenia. At the end of a 180-d acclimation period Jmax25 was 35 μmol(electron) m-2 s-1 for Minquartia and 60 μmol(electron) m-2 s-1 for Swietenia. SLA was higher in Swietenia than in Minquartia. In Minquartia, monthly rate of leaf production per plant (MRLP) was positive (0.22 leaf month-1) after four months in the open. Whereas, in Swietenia MRLP was positive (0.56 leaf month-1) after an acclimation period of two months. After six months in the open, height growth rates were 3.5 and 28 mm month-1 for Minquartia and Swietenia, respectively., a2_The greater acclimation capacity of Swietenia was associated to an enhanced photosynthetic plasticity under full sun. In Minquartia, transition to full-sun conditions and lack of physiological adjustment resulted in severe photoinhibition and loss of leaves., G. F. C. Azevedo, R. A. Marenco., and Obsahuje bibliografii
Plants are able to acclimate to their growth light environments by utilizing a number of short- and long-term mechanisms. One strategy is to prevent accumulation of excess reactive oxygen species that can lead to photoinhibition of photosynthesis. Ureides, generated from purine degradation, have been proposed as antioxidants and involved in certain abiotic stress responses. Eutrema salsugineum (Thellungiella salsuginea) is an extremophilic plant known to exhibit a high degree of tolerance to a variety of abiotic stresses that invariably generate reactive oxygen species. In the present study we have investigated the possible role of the ureide metabolic pathway during acclimation to growth irradiance and its conference of tolerance to photoinhibition in Eutrema. Ureide accumulation was greater under high light growth which also conferred tolerance to photoinhibition at low temperature as measured by the maximal quantum yield of PSII photochemistry. This may represent an adaptive plastic response contributing to the extreme tolerance exhibited by this plant. Our results would provide evidence that ureide accumulation may be involved in abiotic stress as another defence mechanism in response to oxidative stress., V. M. Malik, J. M. Lobo, C. Stewart, S. Irani, C. D. Todd, G. R. Gray., and Obsahuje seznam literatury
The combination of two scion-one rootstock was used for two apple cultivars, ‘Pink Lady’ and ‘Qinguan’, budded on the same, one-year-old Malus hupehensis (Pamp.) Rehd. to reduce the impact of root and pot size and in order to understand the growth, water-use efficiency (WUE), and chlorophyll fluorescence characteristics. The two-scion grafted trees were planted in plastic pots under two water regimes, i.e. 70% field capacity (FC) and 55% FC. Results indicated that different scions were affected differently by drought stress. ‘Pink Lady’ had higher net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) compared with ‘Qinguan’ under both water treatments. However, ‘Qinguan’ had lower minimal fluorescence (F0), higher maximum fluorescence (Fm), and higher maximum photochemical efficiency of photosystem II (Fv/Fm) than ‘Pink Lady’ at 55% FC. Moreover, ‘Qinguan’ had larger shoot dry mass (ShDM) and higher intrinsic WUEI than ‘Pink Lady’ under both water status. Gas-exchange and growth parameters, except for PN and scion diameter, were significantly affected by the cultivar and water treatment. At 70% FC, ShDM was significantly correlated with WUEI. Moreover, WUEI was negatively linearly correlated with g s at either 70 or 55% FC. These results might indicate that ‘Pink Lady’ was more sensitive to drought than ‘Qinguan’. ‘Qinguan’ apple was able to improve WUE more than ‘Pink Lady’ under both well-watered and drought conditions. The growth parameters and photosynthetic capacity of two different scions showed that the combination of double
scion-one rootstock might eliminate the influences of the rootstock and pot size. and X. P. Sun ... [et al.].
To determine the effects of rootstock choice on the scion response to drought stress, we compared the vegetative growth, biomass accumulation, gas exchange, and water-use efficiency (WUE) of ‘Gale Gala’ apple (Malus domestica Borkh.) trees grafted onto nine wild Chinese Malus rootstocks. Compared with the well-watered control, drought treatment limited growth, as manifested by smaller increments in plant height (PH), trunk diameter (TD), total fresh biomass (TB), total dry biomass (TDB), total leaf area (LA), and relative growth rate (RGR). The extent of this effect differed among rootstocks. Stress conditions led to increases in the root/shoot ratio (RSR), leaf thickness (LT), water-holding capacity (WHC), carbon isotope composition (δ13C), and WUE. Decreases were noted in stomatal density (SD), leaf relative water content (RWC), chlorophyll content (Chl), net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (gs), again varying by rootstock. Those that are generally considered more drought-tolerant, e.g., M. sieversii, M. prunifolia, and M. toringoides, had smaller declines in PH, TD, TB, TDB, LA, RGR, SD, RWC, Chl, PN, E, and gs and proportionally greater increases in RSR, LT, WHC, δ13C, and WUE compared with the droughtsensitive M. hupehensis and
M. sieboldii. These results suggest that moisture stress has a significant dwarfing effect in the latter two species. Based on WUE calculations, trees on drought-tolerant rootstocks showed higher tolerance when stressed, whereas those on drought-sensitive rootstocks were less tolerant, as indicated by their lower WUE values., B. H. Liu ... [et al.]., and Obsahuje bibliografii
A hydroponic, greenhouse experiment was conducted to assess the effects of NaCl on growth, gas-exchange parameters, chlorophyll (Chl) content, and ion distribution in seven sesame (Sesamum indicum L.) genotypes (Ardestan, Varamin, Naz-Takshakhe, Naz-Chandshakhe, Oltan, Yekta, Darab). The plants were grown in 4-L containers and subjected to varying levels of salinity (0, 30, and 60 mM NaCl). After 42 days, salt treatments induced decreases of plant fresh and dry mass, total leaf area, and plant height in all genotypes. Increasing NaCl concentration caused significant, genotypedependent decrease in the net photosynthetic rate, stomatal conductance, Chl content, and maximum quantum efficiency of photosystem II, while it increased the intercellular CO2 concentration. Based on the dry matter accumulation under salinity, the genotypes were categorized in two groups, i.e., salt-tolerant and salt-sensitive. The impact of salt on plant ion concentrations differed significantly among the sesame genotypes and between both two groups. The plant Na+ concentrations were significantly lower in Ardestan, Darab, and Varamin genotypes than those found in the remaining genotypes. The highest plant K+ and Ca2+ concentrations together with the lowest Na+/K+ and Na+/Ca2+ ratios were observed in Ardestan, Varamin, and Darab genotypes. Our results indicated the presence of differences in salt response among seven sesame genotypes. It suggested that growth and photosynthesis could depend on ion concentrations and ratios in sesame., A. H. Bazrafshan, P. Ehsanzadeh., and Obsahuje bibliografii
‘Hass‘ and ‘Fuerte‘ avocado plants were grown under well-watered or waterlogged conditions. Results indicated significant effects on the majority of the allometric parameters in waterlogged plants, with ‘Fuerte‘ displaying a more pronounced growth inhibition. Waterlogged conditions caused a progressive and simultaneous decline in net photosynthetic rate and stomatal conductance, earlier in ‘Fuerte‘ than in ‘Hass‘. Maximal potential quantum yield of PSII was unaffected by the soil water regime and/or variety and leaf water potential values in waterlogged plants were not more negative compared with control plants. ‘Fuerte‘ waterlogged plants exhibited increased contents of thiobarbituric acid reactive substances, whereas oxidative injury was not detected in ‘Hass‘. Finally, none of the two cultivars displayed valuable antioxidant potential, as evidenced by the decreased activities of the antioxidant enzymes superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, and ascorbate peroxidase., G. Doupis, N. Kavroulakis, G. Psarras, I. E. Papadakis., and Obsahuje seznam literatury
Recently, there has been rapidly growing interest in the effects of the microbiota on host physiology and behaviour. Due to the nutritional value of bacteria, gut microflora may be particularly important in species that present nuptial gifts during courtship. Here, we explore whether the presence or absence of gut microbiota in males and females of the nuptial gift-giving species Drosophila subobscura (Collin, 1936) alters mating behaviour in terms of female preference, male investment, and female fecundity. We found that females that had been fed antibiotics, compared to females with intact gut bacteria, were more willing to mate with a male that had been fed normally. However female fecundity was higher when both males and females lacked gut bacteria compared to both individuals having a full complement of gut bacteria. This implies that the presence of the microbiota acts to reduce female fecundity in this species, and that male gut bacterial content influences female fecundity. Our results provide further evidence to the growing consensus that the microbiota of an individual may have important effects on both reproductive behaviour and physiology, and suggest that it may also contribute to the nutritional value of the nuptial gift in this system., Benjamin S. Walsh, Chloe Heys, Zenobia Lewis., and Obsahuje bibliografii
Autor čerpá ze své návštěvy pobřežního pásu Francouzské Guyany a Surinamu, především několika tamních chráněných území, v r. 2008, a představuje charakteristické ekosystémy na pobřeží této části Latinské Ameriky. Jde o mangrovy, nížinné zaplavované lesy, močály a vlhké savany, i mělké laguny a suchomilná společenstva na písčitém pobřeží. Na základě pozorování a literatury jsou uvedeny typické nebo něčím zvláštní druhy zdejší flóry i fauny. Za zmínku stojí např. pozorování ohrožených mořských želv kladoucích vejce, včetně kožatky obrovské (Dermochelys coriacea)., The author presents the characteristic coastal ecosystems of French Guyana and Surinam (based on his visit to this coastal area, especially to several protected areas located there, in 2008). The ecosystems include mangroves, lowland flooded forests, swamps and wet savannas, as well as shallow lagoons and xeric communities on the sand coast. Based on observations and literature survey, the article mentions typical or remarkable species of the local fauna and flora. For example, it is worth mentioning observation of threatened sea turtles laying eggs, including the Leatherback Sea Turtle (Dermochelys coriacea)., and Jozef Májsky.
Acclimation to excess light is required for optimizing plant performance under natural environment. The present work showed that the treatment of Arabidopsis leaves with exogenous H2O2 can increase the acclimation of PSII to excess light. Treatments with H2O2 also enhanced the capacity of the mitochondrial alternative respiratory pathway and salicylic acid (SA) content. Our work also showed that the lack in alternative oxidase (AOX1a) in AtAOX1a antisense line and the SA deficiency in NahG (salicylate hydroxylase gene) transgenic mutant attenuated the H2O2-induced acclimation of PSII to excess light. It indicates that the
H2O2-induced acclimation of PSII to excess light could be mediated by the alternative respiratory pathway and SA., Q. Z. Hou, Y. P. Wang, J. Y. Liang, L. Y. Jia, H. Q. Feng, J. Wen, N. Ehmet, J. Y. Bai., and Obsahuje bibliografii
Užovka stromová (Zamenis longissimus) patří mezi kriticky ohrožené druhy naší fauny. V České republice se průkazně vyskytuje pouze ve třech oblastech, přičemž nejzranitelnější je populace v údolí řeky Ohře v západních Čechách, izolovaná stovky kilometrů od souvislého areálu druhu. V letech 2005-07 jsme v Poohří provedli systematický výzkum hadů pod záštitou Fakulty životního prostředí České zemědělské univerzity v Praze a Agentury ochrany přírody a krajiny ČR. Jedinci užovky stromové byli po odchycení změřeni, zváženi, označeni pomocí zástřihů na břišních štítcích (odebrané části štítků posloužily pro analýzu DNA) a detailně vyfotografováni se zaměřením na individuální charakter ošupení (folidózu) hlavy. Na základě zpětných odchytů pak byla odhadována početnost zdejší populace. Během tříletého sledování jsme takto označili a zdokumentovali celkem 432 exemplářů užovky stromové. Jeden ze současných projektů záchranného programu pro užovku stromovou zahrnuje i další odhad početnosti spojený s individuálním značením. Tato aktivita se opakuje zhruba po 10 letech a cílem je zaznamenat změny v početnosti jedinců. V dubnu 2015 se podařilo opětovně odchytit samce označeného v prvním výzkumu pod pořadovým číslem 54. Během výzkumů jsme ho chytili 10x (5x v r. 2005, 2x v r. 2006, 2x v r. 2007 a 1x v r. 2015). To umožnilo zodpovězení i nastolení různých otázek souvisejících např. s věkem a rychlostí růstu., The Aesculapian snake (Zamenis longissimus) is a critically endangered species of Czech fauna. In the Czech Republic it demonstrably occurs in three areas. Its population is most vulnerable in the Ohře river valley in western Bohemia, systematic research into which is presented here. During our three-year research we determined and documented the size and weight of 432 Aesculapian snakes, as well as performing DNA analysis and taking photographs of the individual nature of the scaliness involved. An estimate was made of population figures based on repeated captures., and Karel Janoušek, Radka Musilová, Vít Zavadil.