Melatonin mediates many physiological processes in animals and plants. To examine the potential roles of melatonin in salinity tolerance, we investigated the effects of exogenous melatonin on growth and antioxidant system in cucumber under 200 mM NaCl stress conditions. The results showed that the melatonin-treated plants significantly increased growth mass and antioxidant protection. Under salinity stress, the addition of melatonin effectively alleviated the decrease in the net photosynthetic rate, the maximum quantum efficiency of PSII, and the total chlorophyll content. Our data also suggested that melatonin and the resistance of plants exhibited a concentration effect. The application of 50-150 μM melatonin significantly improved the photosynthetic capacity. Additionally, the pretreatment with melatonin reduced the oxidative damage under salinity stress by scavenging directly H2O2 or enhancing activity of antioxidant enzymes (including superoxide dismutase, peroxidase, catalase, ascorbate peroxidase) and concentrations of antioxidants (ascorbic acid and glutathione). Therefore, the melatonin-treated plants could effectively enhance their salinity tolerance., L. Y. Wang, J. L. Liu, W. X. Wang, Y. Sun., and Obsahuje seznam literatury
Our present work showed that the expression of genes encoding PTOX (terminal oxidase of chlororespiration) and PGR5 (one essential component of cyclic electron transfer) were stimulated by red and blue light, but the stimulation under red light was soon reversed by subsequent far-red light. The expression levels of PTOX and PGR5 under simulated light quality conditions in line with maize-soybean relay strip intercropping (SRI) were obviously lower than those under simulated soybean monocropping (SM), since the lower red:far-red ratio under SRI. Measurements on photosynthetic and chlorophyll fluorescence parameters suggested a decline of assimilatory power supply and a lower nonphotochemical quenching under SRI as compared to SM. In this case, weaker PGR-dependent cyclic electron transfer and chlororespiration under SRI, suggested by lower expression levels of PGR5 and PTOX, could be considered as means of reducing excitation energy dissipation to allocate more power toward CO2 assimilation., X. Sun, X. F. Chen, J. B. Du, W. Y. Yang., and Obsahuje seznam literatury
Expression quantitative trait loci (eQTL) analyses were applied in order to identify genetic factors that are relevant to the expression of a β-isoform Rubisco activase gene in maize, namely ZmRCAβ, in this study. During two years, a maize recombinant inbred line population was measured for ZmRCAβ expression levels at the grain filling stage. Based on a genetic map containing 916 molecular markers, we detected five eQTLs, namely qRCA2.1 on chromosome 2, and qRCA4.1, qRCA4.2, qRCA4.3, and qRCA4.4 on chromosome 4. These eQTLs explained the phenotypic variation ranging from 6.14% to 7.50% with the logarithm of the odd values ranging from 3.11 to 4.96. Based on the position of the eQTLs and ZmRCAβ on the chromosome, qRCA4.2 was inferred as a cis-eQTL and the remaining as a trans-eQTL, suggesting that a combination of both cis- and trans-acting elements might control ZmRCAβ expression. qRCA4.2, qRCA4.3, and qRCA4.4 were repeatedly detected during two years., Q. Sun, Y. Zhang, B. Chen, B. Jia, Z. L. Zhang, M. Cui, X. Kan, H. B. Shi, D. X. Deng, Z. T. Yin., and Obsahuje bibliografii
Extracellular ATP (eATP) has been considered as an important extracellular compound to mediate several physiological processes in plant cells. We investigated the effects of eATP on chlorophyll (Chl) fluorescence characteristics of kidney bean (Phaseolus vulgaris) leaves. Treatment with exogenous ATP at 1 mM showed no significant effect on the maximal photochemical efficiency of PSII. However, the treatment significantly enhanced the values of the PSII operating efficiency (ΦPSII), rate of photosynthetic electron transport through PSII (ETR), and photochemical quenching (qP), while the values of the nonphotochemical quenching (qN) and quantum yield of regulated energy dissipation of PSII (YNPQ) significantly decreased. Our observations indicated that eATP stimulated the PSII photochemistry in kidney bean leaves. Similarly, the treatment with exogenous Ca2+ or H2O2 at 1 mM caused also the significant increase in ΦPSII, qP, and ETR and the significant decrease in qN and YNPQ. LaCl3 (an inhibitor of Ca2+ channels) and dimethylthiourea (a scavenger of H2O2) abolished the effects of exogenous ATP. The results suggest that the role of eATP in enhancing the PSII photochemistry could be related to a Ca2+ or H2O2 signaling pathway., H.-Q. Feng, Q.-S. Jiao, K. Sun, L.-Y. Jia, W.-Y. Tian., and Obsahuje bibliografii
We report here the screening of sixteen cyanobacterial and three green algal strains from Thailand for their potential biohydrogen production. Five filamentous cyanobacterial species, namely Calothrix elenkinii, Fischerella muscicola, Nostoc calcicola, Scytonema bohneri, and Tolypothrix distorta, all possessing nitrogenase activity, showed potentially high biohydrogen production. These five strains showed higher hydrogen production in the absence than in the presence of nitrogen. In particular, F. muscicola had a 17-fold increased hydrogen production under combined nitrogen and sulfur deprived conditions. Among various sugars as a carbon source, glucose at 0.1% (w/v) gave the maximal hydrogen production of 10.9 μmol(H2) mg-1(Chl) h-1 in T. distorta grown in BG11 medium without nitrate. Increasing light intensity up to 250 μmol(photon) m-2 s-1 increased hydrogen production in F. muscicola and T. distorta. Overall results indicate that both F. muscicola and T. distorta have a high potential for hydrogen production amenable for further improvement by using molecular genetics technique., P. Yodsang, W. Raksajit, E.-M. Aro, P. Mäenpää, A. Incharoensakdi., and Obsahuje bibliografické odkazy
Until recently, the Canadian distribution of the blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae), was restricted to Nova Scotia, Prince Edward Island and New Brunswick. The insect was first mentioned in southern Quebec in 1996 and, to date, it has not reached the Lac St-Jean region, where 34% of Canadian blueberry acreage is located. Two questions concerning the northern limit of distribution of the blueberry maggot in Quebec were addressed. First, are wild plants suitable hosts for larval development? We collected the fruit of five wild plants, (e.g. Vaccinium corymbosum, Vaccinium angustifolium, Vaccinium myrtilloides, Gaylussacia baccata, and Aronia melanocarpa) growing in southern Quebec and allowed larvae to complete their development into pupae. Blueberry maggot pupae were recovered from Vaccinium corymbosum, Vaccinium angustifolium, and Gaylussacia baccata, indicating that these plants are suitable for larval development. Second, are harsh winter temperatures a factor limiting the northern distribution of the blueberry maggot? Pupae collected in Quebec and Nova Scotia were put in the soil in the fall and were brought back to the laboratory to determine their supercooling points at different times during winter. The supercooling points of pupae collected in Quebec and Nova Scotia averaged -22.6°C. In natural conditions, air temperatures <-20°C are frequently observed in Quebec in January, February and March. However, due to snow cover, soil temperatures are rarely <-12°C. If -22.6°C constitutes the lower limit for the survival, then winter temperatures are probably not a limiting factor to its northern distribution in Quebec, because blueberry maggot pupae overwinter in the soil., Charles Vincent, Pierre Lemoyne, Sonia Gaul, Kenna Mackenzie., and Obsahuje bibliografii
Thrips are important agricultural pests and accurate identification is important for their effective management. In order to determine species, however, they need to be mounted on slides and the traditional process is time-consuming. The aim of this paper is to describe a simple and fast method to prepare temporary slides for the routine identification of thrips, which is not dependent on their colour and hardness. Four species of thrips of different colours were used in the preparations: Frankliniella occidentalis (yellow with brown tergal markings), Frankliniella schultzei (entirely brown), Haplothrips gowdeyii (dark brown to carmine) and Caliothrips phaseoli (brown to black). Slides of each species were prepared using three different methods: traditional (3 days), simplified (6 h) and fast method (10 min). The thrips on the resulting slides were observed under a microscope and important structures used in their identification were compared. The quality of the slides prepared using the traditional method was superior to those prepared using the other two methods if only the transparency and general position of the insects on the slides were considered. The transparency of the slides prepared using the simplified method was also good, but only for the pale coloured species (yellow and grey-brown). The fast method, on the other hand, was very efficient for routine identification since it resulted in slides of sufficient quality for identifying species regardless of their colour. It is important, however, to stress that the fast method is only suitable for preparing temporary slides for routine identification and is not a substitute for the traditional method of preparing permanent slides., Luís C.P. Silveira, Marcelo M. Haro., and Obsahuje bibliografii
Faunistika není mrtvý obor zoologie. V prvním dílu diskutujeme záludnosti faunistiky a rozdíly mezi faunistikou a sběratelstvím. Měkkýši byli vybráni jako modelová skupina organismů, na nichž ukazujeme historii vývoje oboru v Českých zemích a vývoj měkkýší faunistiky., Faunistics is not a dead subject of zoology. The challenges of faunistics and the difference between faunistics and collecting are discussed. Molluscs were chosen as a model group to show the history of the subject in the Czech Republic and the development of mollusc faunistics., and Vojen Ložek, Lucie Juřičková.
New spectral absorption photometry methods are introduced to estimate chlorophyll (Chl) content of corn leaves by smart phones. The first method acquires light passing through a leaf by smartphone camera, compensating for differences in illumination conditions. In order to improve performance of the method, spectral absorption photometry (SAP) with background illumination has been considered as well. Data were acquired by smartphone camera in Iowa State University maize fields. Various indices were extracted and their correlation with Chl content were examined by Minolta SPAD-502. Hue index in SAP reached R2 value of 0.59. However, with light-aided SAP (LASAP), R2 of 0.97 was obtained. Among traits, the vegetation index gave the most accurate indication. We can conclude that the high performance of LASAP method for estimating Chl content, leads to new opportunities offered by smart phones at much lower cost. This is a highly accurate alternative to SPAD meters for estimating Chl content nondestructively., F. Vesali, M. Omid, H. Mobli, A. Kaleita., and Obsahuje seznam literatury
We investigated the effect of the feeding behaviour of young larvae of Pieris rapae crucivora Boisduval (Pieridae) on parasitism by the parasitoid wasp, Cotesia glomerata (L.) (Braconidae). Young, 1st-3rd instar larvae used approximately three sites for feeding each day. When not feeding, they moved a short distance away from the feeding sites (= feeding marks) and rested. For first, second and third instar larvae, the distances from the new mark, made within 24 h, to larva at rest were, respectively, about 3.5 mm, 5 mm and more than 10 mm. To resume feeding, they moved back to one of the former feeding sites or a new site. The percentage of the feeding marks older than 24 h that attracted parasitoids was less than 50%. Time spent searching for hosts by a parasitoid was short. Larvae placed 5 mm or more from a feeding mark were less parasitized than the larvae placed near a mark. The number of feeding marks affected parasitism. When comparing single-marked and triple-marked leaves, the percentage parasitism of the larvae on the latter was significantly lower than that of the larvae on the former. On triple-marked leaves, parasitoids visited each mark unevenly. Accordingly, the time spent searching each mark differed significantly among the marks. Because of this confusing effect, hosts are considered to be reducing the risk of parasitism. Our results demonstrate that the feeding habits of young larvae of P. rapae crucivora are adaptive in terms of reducing the risk of parasitism by C. glomerata., Aya Nakayama, Keiji Nakamura, Jun Tagawa., and Obsahuje bibliografii