The objective of this study was to use nondestructive measurements as the precise irrigation indices for potted star cluster (Pentas lanceolata). Drought stress was imposed on plants for 0, 3, 5, 7, 12, and 16 d by withholding water. Measurements were conducted on the third leaf counted from the apex (upper leaves) and on the third leaf from the bottom (lower leaves). Within the range of soil water content (SWC) from 10 to 45%, leaf water potential (WP), SWC, and soil matric potential (SMP), chlorophyll fluorescence, photochemical reflectance index (PRI), adjusted normalized difference vegetation index (aNDVI), and the reflectance (R) at 1950 nm (R1950) were measured. The plants reached the temporary wilting point at -3.87 MPa of leaf WP; the maximal fluorescence yield of the light-adapted state (Fm′) ratio of upper-to-lower leaves was 1.7. When the Fm′ ratio was 1.3, it corresponded to lower-leaf WP < -2.27 MPa, SWC < 21%, SMP < -20 kPa, PRI < 0.0443, aNDVI < 0.0301, and R1950 > 8.904; it was the time to irrigate. In conclusion, the Fm′ ratio of upper-to-lower leaves was shown to be a nondestructive predictor of leaf WP and can be used to estimate irrigation timing., C. W. Wu, M. C. Lee, Y. L. Peng, T. Y. Chou, K. H. Lin, Y. S. Chang., and Obsahuje seznam literatury
We examined effects of late-season heat stress (L-SHS) on chlorophyll (Chl) fluorescence parameters and yield of bread wheat as well as roles of phosphate bio-fertilizer (PB-F) and Zn and B to compensate for the likely effects of heat stress. Factors were planting date (21 November and 5 January to coincide with grain filling to L-SHS) as the main factor, no inoculation (control) and inoculation of the seeds with PB-F as the sub-factor, and foliar application of water (control), Zn, B, and Zn + B as 3 L ha-1 as
sub-sub factor. Results revealed that L-SHS reduced maximal quantum yield of PSII photochemistry, effective quantum yield of PSII photochemistry, efficiency of PSII in the light-adapted state, and the grain yield. Moreover, L-SHS increased the nonphotochemical quenching. The PB-F mitigated the effects of L-SHS on Chl fluorescence, yield, and yield components. Among nutrients, the combined Zn + B was more effective in reducing the effects of L-SHS than that of Zn and B alone. Nevertheless, there was an interaction between foliar nutrients application and PB-F, suggesting that Zn application alone had a profound influence on improving Chl fluorescence parameters and increased yield in combination with PB-F., H. R. Eisvand, H. Kamaei, F. Nazarian., and Obsahuje bibliografii
Chlorophyll (Chl) α fluorescence induction (transient), measured by exposing dark-adapted samples to high light, shows a polyphasic rise, which has been the subject of extensive research over several decades. Several Chl fluorescence parameters based on this transient have been defined, the most widely used being the FV [= (FM-F0)]/FM ratio as a proxy for the maximum quantum yield of PSII photochemistry. However, considerable additional information may be derived from analysis of the shape of the fluorescence transient. In fact, several performance indices (PIs) have been defined, which are suggested to provide information on the structure and function of PSII, as well as on the efficiencies of specific electron transport reactions in the thylakoid membrane. Further, these PIs have been proposed to quantify plant tolerance to stress, such as by high light, drought, high (or low) temperature, or N-deficiency. This is an interesting idea, since the speed of the Chl α fluorescence transient measurement (<1 s) is very suitable for high-throughput phenotyping. In this review, we describe how PIs have been used in the assessment of photosynthetic tolerance to various abiotic stress factors. We synthesize these findings and draw conclusions on the suitability of several PIs in assessing stress responses. Finally, we highlight an alternative method to extract information from fluorescence transients, the Integrated Biomarker Response. This method has been developed to define multi-parametric indices in other scientific fields (e.g., ecology), and may be used to combine Chl α fluorescence data with other proxies characterizing CO2 assimilation, or even growth or grain yield, allowing a more holistic assessment of plant performance., A. Stirbet, D. Lazár, J. Kromdijk, Govindjee., and Obsahuje bibliografické odkazy
Chloroplasts utilize photons from solar radiation to synthesize energy-rich molecules of ATPs and NADPHs, which are further used in active cellular processes. Multiprotein complexes (MPCs), including photosystems (PSII and PSI), and the cellular architecture responsible for generation of the proton motive force and the subsequent photophosphorylation, mediate the task of ATP and NADPH synthesis. Both photosystems and other multiprotein assemblies are embedded in thylakoid membranes. Advances in techniques used to study structural biology, biophysics, and comparative genomics and proteomics have enabled us to gain insights of structure, function, and localization of each individual component of the photosynthetic apparatus. An efficient coordination among MPCs is essential for normal functioning of photosynthesis, but there are various stressors that might directly or indirectly interact with photosynthetic components and processes. Cadmium is one of the toxic heavy metals that interact with photosynthetic components and damage photosystems and other MPCs in thylakoids. In plants, iron deficiency shows similar symptoms as those caused by Cd. Our article provides a general overview of chloroplast structure and a critical account of Cd-induced changes in photosystems and other MPCs in thylakoids, and suggests the possible mechanisms involved in mediating these changes. The connection between Cd-induced Fe deficiency and the elevated Cd toxicity under the Fe-deficient condition was also discussed., H. Bashir, M. I. Qureshi, M. M. Ibrahim, M. Iqbal., and Obsahuje seznam literatury
a1_Photosynthesis is one of the most important processes in plant biology and in the development of new methodologies that allow a better understanding and characterization of the photosynthetic status of organisms, which is invaluable. Flow cytometry (FCM) is an excellent tool for measuring fluorescence and physical proprieties of particles but it has seldom been used in photosynthetic studies and thus the full extent of its potentialities, in this field of research, remains unknown. To determine the suitability of FCM in photosynthesis studies, pea plants were exposed to Paraquat and their status was analyzed during 24 h. FCM was used to evaluate the integrity (volume and internal complexity) and the relative fluorescence intensity (FL) of chloroplasts extracted from those plants. To elucidate which type of information the FL conveys, FL values were correlated with the minimum fluorescence level (F0), maximum fluorescence level (Fm) and maximum photochemical efficiency of PSII (Fv/Fm), obtained by using Pulse-Amplitude-Modulation (PAM) fluorometry. Results indicate that: (1) the biomarkers used to evaluate the structural integrity of the chloroplasts were more sensitive to Paraquat exposure than the ones related to fluorescence; (2) the variation of the chloroplast’s structure, as time progressed, pointed to a swelling and subsequent burst of the chloroplast which, in turn, compromised fluorescence emission; (3) FL presented a high and significant correlation with the Fv/Fm and to a lesser degree with Fm but not with F0; (4) pigment content did not reveal significant changes in response to Paraquat exposure and is in agreement with the proposed model, suggesting that the cause for fluorescence decrease is due to chloroplast disruption., a2_In sum, FCM proved to be an outstanding technique to evaluate chloroplastidal functional and structural status and therefore it should be regarded as a valuable asset in the field of photosynthetic research., E. Rodriguez ... [et al.]., and Obsahuje bibliografii
Many RNA recognition motif (RRM)-containing proteins are known to exist in chloroplasts. Major members of the RRM protein family, which are chloroplast ribonucleoproteins (cpRNPs), have been investigated in seed plants, including tobacco and Arabidopsis thaliana, but never in early land plants, such as bryophytes. In this study, we surveyed RRM proteins encoded in the moss Physcomitrella patens genome and predicted 25 putative chloroplast RRM proteins. Among them, two RRM-containing proteins, PpRBP2a and PpRBP2b, resembled cpRNPs and were thus referred to as cpRNP-like proteins. However, knockout mutants of either one or two PpRBP2 genes exhibited a wild type-like phenotype. Unlike Arabidopsis cpRNPs, the levels of mRNA accumulation in chloroplasts were not affected in the PpRBP2 knockout mutants. In addition, the efficiency of RNA editing was also not altered in the mutants. This suggests that PpRBP2a and 2b may be functionally distinct from Arabidopsis cpRNPs., H. Uchiyama, M. Ichinose, M. Sugita., and Obsahuje bibliografické odkazy
Glechoma longituba (Nakai) Kupr. is a perennial shade plant with pharmaceutical importance. The aim of this study was to investigate the effects of light intensity on the growth, photosynthesis, and accumulation of secondary metabolites in G. longituba grown under six different light environments. The high light intensity decreased the leaf size, specific leaf area, and aboveground dry mass, the number of grana per chloroplast, the number of lamella per granum, the thickness of the grana, the apparent quantum efficiency, the chlorophyll (Chl) content, the concentrations of ursolic and oleanolic acid. The high light increased the stomatal density, the stoma size, the number of chloroplast per a cell, the chloroplast size, the dark respiration rate, the light saturation point, the light compensation point, and the Chl a/b ratio. With the reduction in the light intensity, the light-saturated net photosynthetic rate, the aerial dry mass per plant, and the yields of ursolic and oleanolic acid decreased after an initial increase, peaking at 16 and 33% of sunlight levels. Overall, the 16 and 33% irradiance levels were the most efficient in improving the yields and qualities of the medicinal plant. The lower light demand and growth characteristics suggest that G. longituba is an extremely
shade-tolerant plant and that appropriate light intensity management might be feasible to obtain higher yields of secondary metabolites in agricultural management., L. X. Zhang, Q. S. Guo, Q. S. Chang, Z. B. Zhu, L. Liu, Y. H. Chen., and Obsahuje bibliografii
Článek shrnuje současné znalosti o distribuci ryb a její dynamice v našich přehradních nádržích. Především jsou popsány změny distribuce ryb v průběhu a mezi několika důležitými obdobími, jako je třecí období, období sběru potravy a zimní období. Dále je diskutován přínos současného rozvoje metodik vzorkování ryb k porozumění jejich distribučních vzorců., This paper summarizes current knowledge of fish distribution and its dynamics in Czech water reservoirs. The dynamics of fish distribution is described during the three periods, including spawning, feeding and wintering. And the importance of current fish sampling technique innovations for understanding fish distribution patterns is also discussed., and Martin Říha a kolektiv autorů.
This classic area of Silurian and Devonian stratigraphy provided a number of ecological and paleoenvironmental observations during the last decade. Comparative studies of spontaneous successions in abandoned quarries demonstrated that natural processes provide their optimum revitalization. New archaeological records, paleozoological evidence from caves and the discovery of a Late Bronze Age hillfort confirmed that the high biodiversity of this landscape has resulted from a harmonious interaction of natural processes with human activities since the 5th millennium BC. and Vojen Ložek.