Spectroscopic methods in photosynthesis: photosystem stoichiometry and chlorophyll antenna size

1989 ◽  
Vol 323 (1216) ◽  
pp. 397-409 ◽  
Keyword(s):  
Plant Species ◽  
Light Harvesting ◽  
Electron Flow ◽  
Vascular Plant ◽  
Thylakoid Membranes ◽  
Reaction Centre ◽  
Antenna Size ◽  
Fluorescence Measurements ◽  
Photosystem Stoichiometry ◽  
Absorption Of Light

Light-induced absorbance change and fluorescence measurements were employed in the quantitation of photosystem stoichiometry and in the measurement of the chlorophyll (Chl) antenna size in thylakoid membranes. Results with thylakoid membranes from diverse photosynthetic tissues indicated a PSII/PSI reaction-centre stoichiometry that deviates from unity. Cyanobacteria and red algae have a PSII/PSI ratio in the range of 0.3 to 0.7. Chloroplasts from spinach and other vascular-plant species grown under direct sunlight have PSII/PSI = 1.8±0.3. Chlorophyll b -deficient and Chi b -lacking mutants have PSII/PSI > 2. The observation that PSII/PSI ratios are not unity and show a large variation among different photosynthetic membranes appears to be contrary to the conventional assumption derived from the Z-scheme. However, the photosystem stoichiometry is not the only factor that needs to be taken into account to explain the coordination of the two photosystems in the process of linear electron transport. The light-harvesting capacity of each photosystem must also be considered. In cyanobacterial thylakoids (from Synechococcus 6301, PSII/PSI = 0.5±0.2), the phycobilisome-PSII complexes collectively harvest as much light as the PSI complexes. In vascular plant chloroplasts, the light-harvesting capacity of a PSI I complex (250 molecules, Chi a/Chi b = 1.7) is lower than that of a PSI complex (230 Chl, Chl a /Chl b = 8.0) because Chi b has a lower extinction coefficient than Chi a . A differential attenuation of light intensity through the grana further reduces the light absorbed by PSII. Hence, a PSII/PSI ratio greater than one in vascular-plant chloroplasts compensates for the lower absorption of light by individual PSII complexes and ensures that, on average, PSII will harvest about as much light as PSI. In conclusion, distinct light-harvesting strategies among diverse plant species complement widely different photosystem stoichiometries to ensure a balanced absorption of light and a balanced electron flow between the two photoreactions, thereby satisfying the requirement set forth upon the formulation of the Z-scheme by Hill & Bendall ( Nature, Lond. 186, 136-137 (1960)) and by Duysens, Amesz & Kamp ( Nature, Lond . 190, 510-511 (1961)).

scholarly journals Modulation of the light-harvesting chlorophyll antenna size in Chlamydomonas reinhardtii by TLA1 gene over-expression and RNA interference

2012 ◽  
Vol 367 (1608) ◽  
pp. 3430-3443 ◽  
Author(s):  
Mautusi Mitra ◽  
Henning Kirst ◽  
David Dewez ◽  
Anastasios Melis
Keyword(s):  
Gene Expression ◽  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Thylakoid Membranes ◽  
Chloroplast Envelope ◽  
Cell Fractionation ◽  
Reaction Centre ◽  
Antenna Size ◽  
Over Expression ◽  
Chlorophyll Antenna Size

Truncated light-harvesting antenna 1 ( TLA1 ) is a nuclear gene proposed to regulate the chlorophyll (Chl) antenna size in Chlamydomonas reinhardtii . The Chl antenna size of the photosystems and the chloroplast ultrastructure were manipulated upon TLA1 gene over-expression and RNAi downregulation. The TLA1 over-expressing lines possessed a larger chlorophyll antenna size for both photosystems and contained greater levels of Chl b per cell relative to the wild type. Conversely, TLA1 RNAi transformants had a smaller Chl antenna size for both photosystems and lower levels of Chl b per cell. Western blot analyses of the TLA1 over-expressing and RNAi transformants showed that modulation of TLA1 gene expression was paralleled by modulation in the expression of light-harvesting protein, reaction centre D1 and D2, and VIPP1 genes. Transmission electron microscopy showed that modulation of TLA1 gene expression impacts the organization of thylakoid membranes in the chloroplast. Over-expressing lines showed well-defined grana, whereas RNAi transformants possessed loosely held together and more stroma-exposed thylakoids. Cell fractionation suggested localization of the TLA1 protein in the inner chloroplast envelope and potentially in association with nascent thylakoid membranes, indicating a role in Chl antenna assembly and thylakoid membrane biogenesis. The results provide a mechanistic understanding of the Chl antenna size regulation by the TLA1 gene.

The Photosystem Stoichiometry in Thylakoids of Some Australian Shade-adapted Plant Species

1990 ◽  
Vol 17 (6) ◽  
pp. 665 ◽  
Author(s):  
W.S Chow ◽  
J.M Anderson ◽  
A Melis
Keyword(s):  
Plant Species ◽  
Life Forms ◽  
Reaction Centre ◽  
Single Turnover ◽  
Reaction Centres ◽  
Absorbance Change ◽  
Photosystem Stoichiometry ◽  
Chlorophyll Antenna Size ◽  
Oxygen Yield ◽  
Shade Plants

The concentrations of functional photosystem I1 (PSII) reaction centres in leaves and photosystem I reaction centres (P700) in thylakoids isolated from comparable leaves of Australian shade-adapted plant species of diverse taxa, life-forms and habitats were compared. The concentrations of PSII were determined directly in leaves by the oxygen yield per single-turnover flash in the presence of far-red background illumination. The concentrations of P700 were determined by the light-induced absorbance change of thylakoid membranes at 703 nm. On a chlorophyll basis, the amounts of both functional PSII and P700 were lower in shade species than in sun species. The PSII/PSI reaction centre stoichiometries of the shade species ranged from 1.2 to 1.9 indicating that (i) shade-adapted species do not have a fixed 1: 1 ratio; and (ii) their PSWPSI ratios are usually lower than those of sun species (1.7-1.8). We conclude that shade plants display variable photosystem stoichiometry. The results are discussed in terms of the interplay between the adjustment of photosystem stoichiometry and that of the light-harvesting chlorophyll antenna size of each photosystem in the thylakoid membrane of shade species.

Differentiation of new coenomorph in context of the Belgard’s ecomorph system development

2017 ◽  
Vol 28 (1-2) ◽  
pp. 28-35 ◽  
Author(s):  
B. A. Baranovski
Keyword(s):  
Environmental Factors ◽  
Plant Species ◽  
Vascular Plants ◽  
Deciduous Forest ◽  
System Development ◽  
Vascular Plant ◽  
Tabular Form ◽  
Ecological Scales ◽  
The One ◽  
Different Levels

Nowadays, bioecological characteristics of species are the basis for flora and vegetation studying on the different levels. Bioecological characteristics of species is required in process of flora studying on the different levels such as biotopes or phytocenoses, floras of particular areas (floras of ecologically homogeneous habitats), and floras of certain territories. Ramensky scale is the one of first detailed ecological scales on plant species ordination in relation to various environmental factors; it developed in 1938 (Ramensky, 1971). A little later (1941), Pogrebnyak’s scale of forest stands was proposed. Ellenberg’s system developed in 1950 (Ellenberg, 1979) and Tsyganov’s system (Tsyganov, 1975) are best known as the systems of ecological scales on vascular plant species; these systems represent of habitat detection by ecotopic ecomorphs of plant species (phytoindication). Basically, the system proposed by Alexander Lyutsianovich Belgard was the one of first system of plant species that identiified ectomorphs in relation to environmental factors. As early as 1950, Belgard developed the tabulated system of ecomorphs using the Latin ecomorphs abbreviation; he also used the terminology proposed in the late 19th century by Dekandol (1956) and Warming (1903), as well as terminology of other authors. The article analyzes the features of Belgard’s system of ecomorphs on vascular plants. It has certain significance and advantages over other systems of ecomorphs. The use of abbreviated Latin names of ecomorphs in tabular form enables the use shortened form of ones. In the working scheme of Belgard’s system of ecomorphs relation of species to environmental factors are represented in the abbreviated Latin alphabetic version (Belgard, 1950). Combined into table, the ecomorphic analysis of plant species within association (ecological certification of species), biotope or area site (water area) gives an explicit pattern on ecological structure of flora within surveyed community, biotope or landscape, and on environmental conditions. Development and application by Belgrard the cenomorphs as «species’ adaptation to phytocenosis as a whole» were completely new in the development of systems of ecomorphs and, in this connection, different coenomorphs were distinguished. Like any concept, the system of ecomorphs by Belgard has the possibility and necessity to be developed and added. Long-time researches and analysis of literature sources allow to propose a new coenomorph in the context of Belgard’s system of ecomorphs development: silvomargoant (species of forest margin, from the Latin words margo – edge, boundary (Dvoretsky, 1976), margo – margin, ad margins silvarum – along the deciduous forest margins). As an example of ecomorphic characterization of species according to the system of ecomorphs by Belgard (when the abbreviated Latin ecomorph names are used in tabular form and the proposed cenomorph is used), it was given the part of the table on vascular plants ecomorphs in the National Nature Park «Orelsky» (Baranovsky et al). The Belgard’s system of ecomorphs is particularly convenient and can be successfully applied to data processing in the ecological analysis of the flora on wide areas with significant species richness, and the proposed ecomorph will be another necessary element in the Belgard’s system of ecomorphs. 

scholarly journals Improving the knowledge of plant potential biodiversity-ecosystem services links using maps at the regional level in Southern Patagonia

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yamina Micaela Rosas ◽  
Pablo L. Peri ◽  
María Vanessa Lencinas ◽  
Romina Lasagno ◽  
Guillermo J. Martínez Pastur
Keyword(s):  
Ecosystem Services ◽  
Plant Species ◽  
Vegetation Index ◽  
Vascular Plant ◽  
Conservation Strategies ◽  
Cultural Ecosystem Services ◽  
Important Indicator ◽  
Ecological Requirements ◽  
Trade Offs ◽  
Southern Patagonia

Abstract Background Biodiversity supports multiple ecosystem services, whereas species loss endangers the provision of many services and affects ecosystem resilience and resistance capacity. The increase of remote sensing techniques allows to estimate biodiversity and ecosystem services supply at the landscape level in areas with low available data (e.g. Southern Patagonia). This paper evaluates the potential biodiversity and how it links with ecosystem services, based on vascular plant species across eight ecological areas. We also evaluated the habitat plant requirements and their relation with natural gradients. A total of 977 plots were used to develop habitat suitability maps based on an environmental niche factor analysis of 15 more important indicator species for each ecological area (n = 53 species) using 40 explanatory variables. Finally, these maps were combined into a single potential biodiversity map, which was linked with environmental variables and ecosystem services supply. For comparisons, data were extracted and compared through analyses of variance. Results The plant habitat requirements varied greatly among the different ecological areas, and it was possible to define groups according to its specialization and marginality indexes. The potential biodiversity map allowed us to detect coldspots in the western mountains and hotspots in southern and eastern areas. Higher biodiversity was associated to higher temperatures and normalized difference vegetation index, while lower biodiversity was related to elevation and rainfall. Potential biodiversity was closely associated with supporting and provisioning ecosystem services in shrublands and grasslands in the humid steppe, while the lowest values were related to cultural ecosystem services in Nothofagus forests. Conclusions The present study showed that plant species present remarkable differences in spatial distributions and ecological requirements, being a useful proxy for potential biodiversity modelling. Potential biodiversity values change across ecological areas allowing to identify hotspots and coldspots, a useful tool for landscape management and conservation strategies. In addition, links with ecosystem services detect potential synergies and trade-offs, where areas with the lowest potential biodiversity are related to cultural ecosystem services (e.g. aesthetic values) and areas with the greatest potential biodiversity showed threats related to productive activities (e.g. livestock).

Return of the megaherbs: plant colonisation of derelict ANARE station buildings on sub-Antarctic Heard Island

Polar Record ◽  
2004 ◽  
Vol 40 (3) ◽  
pp. 235-243 ◽  
Author(s):  
J. Whinam ◽  
P.M. Selkirk ◽  
A.J. Downing ◽  
Bruce Hull
Keyword(s):  
Plant Species ◽  
Vascular Plants ◽  
Vascular Plant ◽  
Water Tank ◽  
Moss Species ◽  
Left Behind ◽  
Plant Colonisation ◽  
Vascular Plant Species ◽  
Heard Island ◽  
Antarctic Research

Buildings were constructed and artefacts left behind on sub-Antarctic Heard Island, associated with Antarctic research expeditions since 1926. Both bryophytes and vascular plants are colonising many parts of the now derelict buildings. On these structures and artefacts, the authors recorded four species of vascular plants out of the 11 that occur on Heard Island and nine species of mosses out of the 37 recorded from Heard Island. The vascular plant species most frequently recorded colonising structures and artefacts was Pringlea antiscorbutica (288 occurrences), with the area colonised varying from 0.3 cm2 to 430.0 cm2. Muelleriella crassifolia was the moss species that was most frequently recorded (14 occurrences), colonising areas from 2.1 cm2 to 12.9 cm2. The highest number of bryophyte species (seven) was recorded on the stone and cement of the ‘water tank.’ Pringlea antiscorbutica, Poa cookii, Azorella selago, Muelleriella crassifolia, Bryum dichotomum, Dicranoweisia brevipes and Schistidium apocarpum are all expected to continue to colonise the ANARE ruins, as well as areas that have become available since building removal and also possibly areas bared by further deglaciation.

The vascular plant diversity of Dzungarian Gobi in western Mongolia, with an annotated checklist

Phytotaxa ◽  
2021 ◽  
Vol 501 (1) ◽  
pp. 1-55
Author(s):  
SHUKHERDORJ BAASANMUNKH ◽  
BATLAI OYUNTSETSEG ◽  
CHULUUNKHUYAG OYUNDARI ◽  
KHURELPUREV OYUNDELGER ◽  
MAGSAR URGAMAL ◽  
...  
Keyword(s):  
Plant Species ◽  
Threatened Species ◽  
Conservation Status ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Species Number ◽  
Endemic Plants ◽  
Mountain Area ◽  
Western Mongolia ◽  
Comprehensive Survey

The Dzungarian Gobi (DzG), one of 16 phytogeographical regions in the country, is located in the southwestern part of Khovd province in western Mongolia. It comprises some of Mongolia’s largest reserves, namely the Great Gobi B Strictly Protected Area and the National Park Bulgan gol-Ikh Ongog. We conducted a comprehensive survey of the area’s floristic diversity between 2009 and 2019 by collecting vascular plants from different vegetation types in various seasons. In addition, we critically checked relevant published literature and material from the herbaria ALTB, GLM, GWF, HAL, KHU, LE, MW, NS, OSBU, UBA, and UBU to determine the occurrence of vascular plant species in the DzG region. Based on our collection data, a comprehensive checklist of DzG’s flora was compiled, representing 913 vascular plant taxa (including 34 subspecies and one variety) belonging to 329 genera and 70 families. Twenty-one taxa were newly found in the DzG region. We also investigated the conservation status of all species noted, and 19 endemic plants and 96 threatened species, including six critically endangered, 26 endangered, 57 vulnerable, and seven near threatened plants were recognized in this region. Eight rare species were newly assessed according to regional conservation status based on GeoCat and IUCN. The richest plant families found were Asteraceae (153 species), Fabaceae (77 species), Amaranthaceae (69 species), and Poaceae (68 species). Several uncertain endemic and non-endemic plants remain still discussion, such as Papaver baitagense and Rosa baitagensis; thus, further studies are needed on their taxonomic and conservation status. For each taxon, we provide its distribution in the region, elevation range, voucher number, and additional references. Finally, we analyzed species hotspots of DzG, based on three different plant species richness criteria: i. all recorded species, ii. endemic species, and iii. threatened species using our georeferenced records. The most diverse hotspot area in DzG is the Baitag Bogd Mountain area, which comprises the highest species number of all three richness criteria.

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