Search

Societal Impact Statement: The human population is expected to reach 9.7 billion in the next 30 years, increasing the strain on our already precarious food system. Climate change is shifting weather patterns, leading to unpredictable and catastrophic events that further threaten the agronomic sector. Plant scientists are implementing biotechnological tools to sustainably increase both the production and nutritional content of our crops. Engineering GOLDEN2‐LIKE (GLK) transcription factors is a promising route to improve photosynthesis, as well as other important agronomical traits, to achieve food security for a growing population under an unpredictable climate. Summary: Using agricultural biotechnology to increase the photosynthetic efficiency of crops has been a focus of plant science research over the last two decades. Transcription factors coordinate the expression of gene networks that are the basis of plant development and physiological responses and, as such, are good targets to help improve photosynthesis. Among the known plant transcriptional regulators, GOLDEN2‐LIKE transcription factors (GLKs) may be ideal candidates to improve photosynthesis in crops, as they are master regulators of genes associated with photosynthesis and chloroplast biogenesis across a broad diversity of plant lineages. Moreover, recent work has revealed their involvement in environmental response, pathogen defence and development regulation across the plant's whole life cycle. Thus, manipulating GLK expression and activity, alone or likely in combination with other modifications, has clear potential to improve plant development and growth. Here, we review the research into GLK function and discuss the potential of these key transcription factors as biotechnological tools to enhance photosynthetic efficiency and stress tolerance in crops. Additionally, we take advantage of the vast plant genome and transcriptome datasets available to explore the evolutionary history of GLKs across the plant kingdom and discuss the implications for their adoption into crop engineering projects. [ABSTRACT FROM AUTHOR]

The chloroplast envelope transporter LCIA, characterized in the study discussed here, is a bicarbonate channel that facilitates diffusion of bicarbonate into the chloroplast which is driven by the concentration gradient created by active pumping of bicarbonate at the plasma membrane. Keywords: Bicarbonate; carbonic anhydrase; CCM; engineering; photosynthesis; transporter EN Bicarbonate carbonic anhydrase CCM engineering photosynthesis transporter 3402 3405 4 06/30/23 20230627 NES 230627 B The CO b SB B 2 b sb B -concentrating mechanism (CCM) used by eukaryotic algae represents an inorganic carbon pump [Ci: bicarbonate (HCO b SB B 3 b sb SP B - b sp B ), carbon dioxide (CO b SB B 2 b sb B ), and carbonic acid (CO b SB B 3 b sb SP B 2- b sp B )] that generates an elevated concentration of CO b SB B 2 b sb around Rubisco, which promotes carbon fixation. Bicarbonate, carbonic anhydrase, CCM, engineering, photosynthesis, transporter LCIB functions as a carbonic anhydrase: evidence from yeast and Arabidopsis carbonic anhydrase knockout mutants. [Extracted from the article]

Changes in carotenoid profile can influence the content of important molecules such as xanthophylls (photoprotection), apocarotenoid growth regulators, and signaling molecules and plant hormones. Keywords: apocarotenoids; carotenoids; metabolic engineering; photosynthesis; phytohormones; stress tolerance; yield EN apocarotenoids carotenoids metabolic engineering photosynthesis phytohormones stress tolerance yield 1946 1950 5 02/21/23 20230315 NES 230315 Carotenoids are isoprenoid compounds synthesized by all photosynthetic organisms and several heterotrophic microorganisms. Therefore, enhancing carotenoid content, in particular provitamin A carotenoids, has been one of the preferred targets of plant genetic engineering, resulting in biofortified cereals, fruits, and tubers, including rice, tomato, and potato. [Extracted from the article]

R is one of the most commonly used analytical tools in the plant sciences. To identify key trends in general reported R use and patterns in photosynthesis research, we explored the frequency of R use in 2966 articles published in the 377 journals with 'photosynthesis' in the title from 2010 to 2019 using the Web of Science search. Solutions provided by each R package cited in the articles or online sources was recorded and classified. The percentage of research articles reporting R use increased linearly from 3.6% in 2010 to 12.5% in 2019. The three main categories of R package solutions were 'general statistical calculations and graph packages' (G); 'photosynthesis special-purpose packages' (S); and 'genetic and evolutionary packages' (E). The top five R packages cited were nlme (G), lme4 (G), multcomp (G), plantecophys (S), and ape (E). The increasing popularity of R use in photosynthesis research is due to its user-friendly and abundant open-source codes online for handling specific issues, particularly in fitting photosynthesis models. These findings are limited by the number of articles and online sources, but they reveal a significant increase in usage in photosynthesis research over the past decade and have a bright prospect in the future. [ABSTRACT FROM AUTHOR]

[22] discuss how quantitative genetics can be used to discover useful trait variation and design strategies to improve crop photosynthesis, based on readily available crop plant germplasm. Tools to assess and utilize natural variation in photosynthesis Although the germplasm of most crops already appears to show significant variation for photosynthetic traits, genetic diversity within a crop's germplasm is expected to be significantly less than that of its wild progenitors. Keywords: C 3 photosynthesis; C 4 photosynthesis; CO 2 assimilation; genetic variation; plant breeding; biotechnology EN C 3 photosynthesis C 4 photosynthesis CO 2 assimilation genetic variation plant breeding biotechnology 3053 3056 4 05/25/22 20220523 NES 220523 B Advances in breeding practices during the "Green Revolution" in the 1960s have helped to maintain crop yields in the face of population growth. [Extracted from the article]

Gas exchange techniques revolutionized plant research and advanced understanding, including associated fluxes and efficiencies, of photosynthesis, photorespiration, and respiration of plants from cellular to ecosystem scales. These techniques remain the gold standard for inferring photosynthetic rates and underlying physiology/biochemistry, although their utility for high-throughput phenotyping (HTP) of photosynthesis is limited both by the number of gas exchange systems available and the number of personnel available to operate the equipment. Remote sensing techniques have long been used to assess ecosystem productivity at coarse spatial and temporal resolutions, and advances in sensor technology coupled with advanced statistical techniques are expanding remote sensing tools to finer spatial scales and increasing the number and complexity of phenotypes that can be extracted. In this review, we outline the photosynthetic phenotypes of interest to the plant science community and describe the advances in high-throughput techniques to characterize photosynthesis at spatial scales useful to infer treatment or genotypic variation in field-based experiments or breeding trials. We will accomplish this objective by presenting six lessons learned thus far through the development and application of proximal/remote sensing-based measurements and the accompanying statistical analyses. We will conclude by outlining what we perceive as the current limitations, bottlenecks, and opportunities facing HTP of photosynthesis. [ABSTRACT FROM AUTHOR]

The classical theory of safety--efficiency trade-off is a common theme in plant sciences. Despite safety and efficiency partly compensating for each other physiologically (namely, there is a compensation effect, CE, among traits from the "whole" organism perspective), they are always mathematically described as a trade-off against one another. However, the compensation effect has never been defined and quantified, let alone its role in the xylem water transport and subsequently photosynthesis. Here, we developed an alternative theory to define the CE as a positive relationship between safety and efficiency, and further define a new trade-off index, SETO, that is expressed as CE multiplied by a trade-off factor (differing from the classical average trade-off value). Then, we tested SETO- and CE-photosynthetic rate relationships across different levels based on a common garden experiment using nine conifers and published data for gymnosperms. The results demonstrated that the compensation effect in xylem functions was the dominant force in facilitating photosynthetic rates from species- to phylum-scale. By integrating the compensation effect into the xylem hydraulic functional strategy, our study clearly indicated that the compensation effect is the evolutionary basis for the coordination of xylem hydraulic and photosynthesis physiology. [ABSTRACT FROM AUTHOR]

This chapter is dedicated to the memory of Pierre Gadal a former Series Editor for Advances in Botanical Research. Its aim is to describe the research that has been done in his laboratory covering essentially the period 1970-2000 and provides first-hand testimony about how it has been done. Besides the scientific output concerning CO2 and nitrogen assimilation and their regulation described in this chapter Pierre Gadal has been very influential in plant science in France through his interactions with the University system but also with CNRS and INRA communities. Through the organization of the doctorate school in University of Paris-Sud he has helped train hundreds of students, and more specifically concerning his own research group, more than 10 of his former students have become CNRS researchers, many with high positions and responsibilities, a similar number INRA researchers and Professors and Assistant Professors in the University system. Fourteen different colleagues have contributed to this chapter, each with his own perception, heart and guts, a further testimony to the exceptional human and scientific qualities of Pierre. [ABSTRACT FROM AUTHOR]

Plants confront several environmental stresses that are crucial in defining plant productivity. Among these environmental stresses, drought stress is recognized as the foremost abiotic factor which affects the food security around the globe due to its negative impact on the plant development, and quality of plant products. Because of this, drought stress has gained an imperative appearance in the field of plant sciences in recent years. Silicon (Si), an agronomically essential mineral nutrient, is recognized highly advantageous in enhancing plant growth at various phases of plant life cycle under water deficit circumstances. Si has been considered extensively useful in mitigating harmful consequences of drought stress by enhancing root H 2 O absorption, regulating uptake of nutrients, reducing transpiration rate, improving photosynthetic activity, increment in the production of compatible solutes and by elevating plant antioxidant defense functioning. Si also known to improve plant endurance to limited water availability by inducing the functioning of various stress associated genes. To maximize the potential benefits and sustainable efficiency of Si in agriculture, it is of crucial importance to gain knowledge about the underlying mechanisms of how Si counteract stress conditions. Various findings suggested that Si increases the plant's immune system against drought stress, and application of Si is an important approach to shield plants from adverse stress conditions and soil nutrient depletion. This paper shows that Si has imperative and noteworthy impacts on improving plant tolerance to drought stress via maintaining cellular homeostasis. Present review mainly provides an insight into silicon role as beneficial element to alleviate drought stress in plants by regulating their morphological, physicochemical and molecular characteristics. • Silicon (Si) is an agronomically essential mineral nutrient. • Si is highly advantageous in enhancing plant growth and productivity under drought stress conditions. • Si application improve plant tolerance to drought stress by triggering the expression of various stress associated genes. [ABSTRACT FROM AUTHOR]

Keywords: chlorophyll fluorescence; coordination; development; function; photosynthesis; plant water-use-efficiency; stomata EN chlorophyll fluorescence coordination development function photosynthesis plant water-use-efficiency stomata 350 352 3 03/22/22 20220415 NES 220415 What inspired your interest in plant science? I have a number of favourite plants, the top spot being shared between I Gingko i and I Dicksonia i tree ferns, possibly for similar reasons, i.e. the fact that they are "ancient plants", having first evolved many millions of years ago, and therefore provide us with a glimpse of the past. Chlorophyll fluorescence, coordination, development, function, photosynthesis, plant water-use-efficiency, stomata. [Extracted from the article]

The elemental carbon and nitrogen content, as well as the stable isotopic composition of plants, can provide information on their nutrient dynamics and physiological characteristics. With applications ranging from paleoecology to ecological modeling, this information is critical in biodiversity conservation and management especially for highly dynamic ecosystems such as the Philippines'. Here, we determined the carbon and nitrogen content and their stable isotopic ratios in selected Philippine flora across different classifications and photosynthetic pathways. Fully developed leaves from different species of grasses, succulents, shrubs, and trees were collected and analyzed using isotope ratio mass spectrometry for carbon and nitrogen concentration and stable isotopic composition. Our results showed that trees had the highest carbon and nitrogen content, while grasses that utilized the C4 photosynthetic pathway were most efficient in terms of nutrient utilization as evidenced by their high C/N ratios. Foliar stable carbon isotopic composition of the surveyed Philippine flora was an excellent measure for distinguishing among photosynthetic pathways. The stable nitrogen isotopic composition was not distinct across plant classifications and showed indications of being sensitive to environmental factors, thus limiting its use for phylogenetic tracing. Our findings thus indicate that foliar carbon and nitrogen content and stable isotopic composition provide insights that cannot be easily achieved with other measurements. [ABSTRACT FROM AUTHOR]

This special issue is dedicated to Jean-Marc Ducruet whose most relevant contributions to photosynthesis research have been the use of the thermoluminescence (TL) technique and the construction of many TL apparatus for a number of laboratories in different countries. Jean-Marc Ducruet liked to propagate the TL method, to help especially young scientists, to travel and visit the laboratories of his friends and to construct for them TL devices. TL in photosynthesis is a technique that is mainly used to study charge recombination reactions in photostystem II (PSII). This emission was first observed as a delayed burst of luminescence superimposed over the exponential luminescence decay (corresponding to B-band emission in TL) recorded at a constant temperature (Bertsch & Azzi, 1965). [Extracted from the article]

SUMMARY: Deep insights into chloroplast biogenesis have been obtained by mutant analysis; however, in C4 plants a relevant mutant collection has only been developed and exploited for maize. Here, we report the initial characterization of an ethyl methyl sulfonate‐induced mutant population for the C4 model Setaria viridis. Approximately 1000 M2 families were screened for the segregation of pale‐green seedlings in the M3 generation, and a subset of these was identified to be deficient in post‐transcriptional steps of chloroplast gene expression. Causative mutations were identified for three lines using deep sequencing‐based bulked segregant analysis, and in one case confirmed by transgenic complementation. Using chloroplast RNA‐sequencing and other molecular assays, we describe phenotypes of mutants deficient in PSRP7, a plastid‐specific ribosomal protein, OTP86, an RNA editing factor, and cpPNP, the chloroplast isozyme of polynucleotide phosphorylase. The psrp mutant is globally defective in chloroplast translation, and has varying deficiencies in the accumulation of chloroplast‐encoded proteins. The otp86 mutant, like its Arabidopsis counterpart, is specifically defective in editing of the rps14 mRNA; however, the conditional pale‐green mutant phenotype contrasts with the normal growth of the Arabidopsis mutant. The pnp mutant exhibited multiple defects in 3′ end maturation as well as other qualitative changes in the chloroplast RNA population. Overall, our collection opens the door to global analysis of photosynthesis and early seedling development in an emerging C4 model. Significance Statement: Deep understanding of photosynthetic mechanisms in C4 plants is relevant to evolutionary, biochemical and applied aspects of plant science. Setaria viridis is an emerging C4 model system, and we present the first study of mutants defective in chloroplast functions required for photosynthesis. [ABSTRACT FROM AUTHOR]

Background: Over the last years, several plant science labs have started to employ fluctuating growth light conditions to simulate natural light regimes more closely. Many plant mutants reveal quantifiable effects under fluctuating light despite being indistinguishable from wild-type plants under standard constant light. Moreover, many subtle plant phenotypes become intensified and thus can be studied in more detail. This observation has caused a paradigm shift within the photosynthesis research community and an increasing number of scientists are interested in using fluctuating light growth conditions. However, high installation costs for commercial controllable LED setups as well as costly phenotyping equipment can make it hard for small academic groups to compete in this emerging field. Results: We show a simple do-it-yourself approach to enable fluctuating light growth experiments. Our results using previously published fluctuating light sensitive mutants, stn7 and pgr5, confirm that our low-cost setup yields similar results as top-prized commercial growth regimes. Moreover, we show how we increased the throughput of our Walz IMAGING-PAM, also found in many other departments around the world. We have designed a Python and R-based open source toolkit that allows for semi-automated sample segmentation and data analysis thereby reducing the processing bottleneck of large experimental datasets. We provide detailed instructions on how to build and functionally test each setup. Conclusions: With material costs well below USD$1000, it is possible to setup a fluctuating light rack including a constant light control shelf for comparison. This allows more scientists to perform experiments closer to natural light conditions and contribute to an emerging research field. A small addition to the IMAGING-PAM hardware not only increases sample throughput but also enables larger-scale plant phenotyping with automated data analysis. [ABSTRACT FROM AUTHOR]

Achieving global food security for the estimated 9 billion people by 2050 is a major scientific challenge. Crop productivity is fundamentally restricted by the rate of fixation of atmospheric carbon. The dedicated enzyme, RubisCO, has a low turnover and poor specificity for CO2. This limitation of C3 photosynthesis (the basic carbon-assimilation pathway present in all plants) is alleviated in some lineages by use of carbon-concentrating-mechanisms, such as the C4 cycle—a biochemical pump that concentrates CO2 near RubisCO increasing assimilation efficacy. Most crops use only C3 photosynthesis, so one promising research strategy to boost their productivity focuses on introducing a C4 cycle. The simplest proposal is to use the cycle to concentrate CO2 inside individual chloroplasts. The photosynthetic efficiency would then depend on the leakage of CO2 out of a chloroplast. We examine this proposal with a 3D spatial model of carbon and oxygen diffusion and C4 photosynthetic biochemistry inside a typical C3-plant mesophyll cell geometry. We find that the cost-efficiency of C4 photosynthesis depends on the gas permeability of the chloroplast envelope, the C4 pathway having higher quantum efficiency than C3 for permeabilities below 300 μm/s. However, at higher permeabilities the C4 pathway still provides a substantial boost to carbon assimilation with only a moderate decrease in efficiency. The gains would be capped by the ability of chloroplasts to harvest light, but even under realistic light regimes a 100% boost to carbon assimilation is possible. This could be achieved in conjunction with lower investment in chloroplasts if their cell surface coverage is also reduced. Incorporation of this C4 cycle into C3 crops could thus promote higher growth rates and better drought resistance in dry, high-sunlight climates. [ABSTRACT FROM AUTHOR]

Chloroplast plays an important role in the plant life cycle. However, the details of its development remain elusive in rice. In this study, we report the fine-mapping of a novel rice gene wpb1 (white panicle branch 1), which affects chloroplast biogenesis, from a tropical japonica variety that results in an albino panicle branches at and after the heading stage. The wpb1 variety was crossed with Nipponbare to generate the F2 and BC1F2 populations. Green and white panicle branch phenotypes with a 3:1 segregation ratio was observed in the F2 population. Bulked segregant analysis (BSA) based on whole genome resequencing was conducted to determine the wpb1 locus. A candidate interval spanning from 11.35 to 23.79M (physical position) on chromosome 1 was identified. The results of BSA analysis were verified by a 40K rice SNP-array using the BC1F2 population. A large-scale F2 population was used to pinpoint wpb1, and the locus was further narrowed down to a 95-kb interval. Furthermore, our results showed that the expression levels of the majority of the genes involved in Chl biosynthesis, photosynthesis and chloroplast development were remarkably affected in wpb1 variety and in F2 plants with a white panicle branch phenotype. In line with the results mentioned above, anatomical structural examination and chlorophyll (Chl) content measurement suggested that wpb1 might play an important role in the regulation of chloroplast development. Further cloning and functional characterization of the wpb1 gene will shed light on the molecular mechanism underlying chloroplast development in rice. [ABSTRACT FROM AUTHOR]

Leaf senescence plays an important role in the improvement of maize kernel yields. However, the underlying regulatory mechanisms of leaf senescence in maize are largely unknown. We isolated ZmVQ52 and studied the function of ZmVQ52 which encoded, a VQ family transcription factor. ZmVQ52 is constitutively expressed in maize tissues, and mainly expressed in the leaf; it is located in the nucleus of maize protoplasts. Four WRKY family proteins—ZmWRKY20, ZmWRKY36, ZmWRKY50, and ZmWRKY71—were identified as interacting with ZmVQ52. The overexpression of ZmVQ52 in Arabidopsis accelerated premature leaf senescence. The leaf of the ZmVQ52-overexpression line showed a lower chlorophyll content and higher senescence rate than the WT. A number of leaf senescence regulating genes were up-regulated in the ZmVQ52-overexpression line. Additionally, hormone treatments revealed that the leaf of the ZmVQ52-overexpressed line was more sensitive to salicylic acid (SA) and jasmonic acid (JA), and had an enhanced tolerance to abscisic acid (ABA). Moreover, a transcriptome analysis of the ZmVQ52-overexpression line revealed that ZmVQ52 is mainly involved in the circadian pathway and photosynthetic pathways. [ABSTRACT FROM AUTHOR]

Ceratopteris thalictroides, a model fern, has two kinds of gametophytes with different sex expression: male and hermaphrodite. Hermaphroditic gametophytes have one or several archegonia beneath the growing point and a few antheridia at the base or margin. Male gametophytes show a spoon-like shape with much longer than the width and produce many antheridia at the margin and surface. The results of chlorophyll fluorescence detection showed that the photochemical efficiency of hermaphrodites was higher than that of males. By using two-dimensional electrophoresis and mass spectrometry, the differentially abundant proteins in hermaphroditic and male gametophytes were identified. A total of 1136 ± 55 protein spots were detected in Coomassie-stained gels of proteins from hermaphroditic gametophytes, and 1130 ± 65 spots were detected in gels of proteins from male gametophytes. After annotation, 33 spots representing differentially abundant proteins were identified. Among these, proteins involved in photosynthesis and chaperone proteins were over-represented in hermaphrodites, whereas several proteins involved in metabolism were increased in male gametophytes in order to maintain their development under relatively nutritionally deficient conditions. Furthermore, the differentially abundant cytoskeletal proteins detected in this study, such as centrin and actin, may be involved in the formation of sexual organs and are directly related to sex expression. These differentially abundant proteins are important for maintaining the development of gametophytes of different sexes in C. thalictroides. [ABSTRACT FROM AUTHOR]

Superoxide dismutases (SODs) protect against reactive oxygen species (ROS) by detoxifying superoxide. Three types of SOD are present in plants: FeSOD, CuSOD, and MnSOD. The Arabidopsis thaliana genome contains three FeSOD genes, in which two (FSD2, and FSD3) are targeted to chloroplast thylakoids. Loss of FSD2 or FSD3 expression impairs growth and causes leaf bleaching. FSD2 and FSD3 form heterocomplexes present in chloroplast nucleoids, raising the question of whether FSD2 and FSD3 are functionally interchangeable. In this study, we examined how loss of FSD2 or FSD3 expression affects photosynthetic processes and whether overexpression of one compensates for loss of the other. Whereas loss of the cytosolic FSD1 had little effect, an fsd2 mutant exhibited increased superoxide production, reduced chlorophyll levels, lower PSII efficiency, a lower rate of CO2 assimilation, but elevated non-photochemical quenching (NPQ). In contrast, fsd3 mutants failed to survive beyond the seedling stage and overexpression of FSD2 could not rescue the seedlings. Overexpression of FSD3 in an fsd2 mutant, however, partially reversed the fsd2 mutant phenotype resulting in improved growth characteristics. Overexpression of FSD2 or FSD3, either individually or together, had little effect. These results indicate that, despite functioning as FeSODs, FSD2 and FSD3 are functionally distinct. [ABSTRACT FROM AUTHOR]

Waterlogging stress is one of the most important abiotic stresses limiting sorghum growth and development. Consequently, the responses of sorghum to waterlogging must be monitored and studied. This study investigated changes in the leaf water status, xylem exudation rate, leaf anatomical structure, leaf temperature and photosynthetic performance. Waterlogging-tolerant (Jinuoliang 01, abbreviated JN01) and waterlogging-sensitive (Jinza 31, abbreviated JZ31) sorghum cultivars were planted in pots. The experiment was carried out using a split block design with three replications. Waterlogging stress was imposed at the sorghum five-leaf stage. The leaf free water content (FWC) and relative water content (RWC) decreased under the waterlogged condition. The leaf thickness was thinner under the waterlogged condition, and the main changes occurred in the upper epidermal and mesophyll cells. Gas exchange parameters and the xylem exudation rate were also restrained by waterlogging; however, greater responses of these parameters were observed in JZ31. JZ31 had a higher leaf-air temperature difference (ΔT) than JN01. We found that changes in ΔT were always consistent with changes in the RWC and the gas exchange parameters. ΔT was significantly associated with the leaf RWC, photosynthetic rate (Pn) and transpiration rate (Tr). The results suggest that ΔT may be an indicator reflecting the water status in leaves and can be used to evaluate the tolerance of sorghum to waterlogging. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Plants have been elements in games throughout history. In an era where "digital pushback" is becoming more common, the impressions that representations of plants in board games have on an audience is not to be overlooked. By acknowledging the importance, beauty and history of the botanic world and its considerable impact on the daily lives of human beings connected to it, modern board games may offer an entertainment route towards awareness as well as an educational resource to challenge plant blindness. Summary Plant blindness is the inability to appreciate plants in one's own environment, in the biosphere as a whole and their relationship to human affairs. Here, we discuss a community of interests in which we suggest that an appreciation of plants is vital for success: namely the world of modern board gaming. We present a classification system for the presentation of plants in the 500 most popular modern board games, where games are categorised based on their complexity, and representation and portrayal of plants. This initial mapping exercise defines a potential scope for the future analysis of how modern board games may offer a novel and interactive entertainment mechanism to challenge plant blindness and a framework for future analysis work in this area. [ABSTRACT FROM AUTHOR]

While potassium fertilization increases growth yield in Brazilian eucalyptus plantations, it could also increase water requirements, making trees more vulnerable to drought. Sodium fertilization, which has been shown to promote eucalyptus growth compared to K-deficient trees, could partially mitigate this adverse effect of potassium. However, little is known about the influence of K and Na fertilization on the tree metabolic response to water deficit. The aim of the present study was thus to analyze the transcriptome of leaves sampled from Eucalyptus grandis trees subjected to 37% rainfall reduction, and fertilized with potassium (K), sodium (Na), compared to control trees (C). The multifactorial experiment was set up in a field with a throughfall exclusion system. Transcriptomic analysis was performed on leaves from two-year-old trees, and data analyzed using multifactorial statistical analysis and weighted gene co-expression network analysis (WGCNA). Significant sets of genes were seen to respond to rainfall reduction, in interaction with K or Na fertilization, or to fertilization only (regardless of the water supply regime). The genes were involved in stress signaling, primary and secondary metabolism, secondary cell wall formation and photosynthetic activity. Our focus on key genes related to cation transporters and aquaporins highlighted specific regulation of ion homeostasis, and plant adjustment to water deficit. While water availability significantly affects the transcriptomic response of eucalyptus species, this study points out that the transcriptomic response is highly dependent on the fertilization regime. Our study is based on the first large-scale field trial in a tropical region, specifically designed to study the interaction between water availability and nutrition in eucalyptus. To our knowledge, this is the first global transcriptomic analysis to compare the influence of K and Na fertilization on tree adaptive traits in water deficit conditions. [ABSTRACT FROM AUTHOR]

Due to its tropical origin and adaptation, rice is significantly impacted by cold stress, and consequently sustains large losses in growth and productivity. Currently, rice is the second most consumed cereal in the world and production losses caused by extreme temperature events in the context of "major climatic changes" can have major impacts on the world economy. We report here an analysis of rice genotypes in response to low-temperature stress, studied through physiological gas-exchange parameters, biochemical changes in photosynthetic pigments and antioxidants, and at the level of gene and protein expression, towards an understanding and identification of multiple low-temperature tolerance mechanisms. The first effects of cold stress were observed on photosynthesis among all genotypes. However, the tropical japonica genotypes Secano do Brazil and Cypress had a greater reduction in gas exchange parameters like photosynthesis and water use efficiency in comparison to the temperate japonica Nipponbare and M202 genotypes. The analysis of biochemical profiles showed that despite the impacts of low temperature on tolerant plants, they quickly adjusted to maintain their cellular homeostasis by an accumulation of antioxidants and osmolytes like phenolic compounds and proline. The cold tolerant and sensitive genotypes showed a clear difference in gene expression at the transcript level for OsGH3-2, OsSRO1a, OsZFP245, and OsTPP1, as well as for expression at the protein level for LRR-RLKs, bHLH, GLYI, and LTP1 proteins. This study exemplifies the cold tolerant features of the temperate japonica Nipponbare and M202 genotypes, as observed through the analysis of physiological and biochemical responses and the associated changes in gene and protein expression patterns. The genes and proteins showing differential expression response are notable candidates towards understanding the biological pathways affected in rice and for engineering cold tolerance, to generate cultivars capable of maintaining growth, development, and reproduction under cold stress. We also propose that the mechanisms of action of the genes analyzed are associated with the tolerance response. [ABSTRACT FROM AUTHOR]

Certain plant genotypes can achieve optimal growth under appropriate environmental conditions. Under high planting density conditions, plants undergo competition for uptake and utilization of light and nutrients. However, the relationship between whole-genome expression patterns and the planting density in perennial woody plants remains unknown. In this study, whole-genome RNA sequencing of poplar (Populus × euramericana) was carried out at three different sampling heights to determine gene expression patterns under high (HD) and low (LD) planting densities. As a result, 4,004 differentially expressed genes (DEGs) were detected between HD and LD, of which 2,300, 701, and 1,003 were detected at the three positions, upper, middle and bottom, respectively. Function annotation results further revealed that a large number of the DEGs were involved in distinct biological functions. There were significant changes in the expression of metabolism-related and stimulus-related genes in response to planting density. There were 37 DEGs that were found at all three positions and were subsequently screened. Several DEGs related to plant light responses and photosynthesis were observed at different positions. Meanwhile, numbers of genes related to auxin/indole-3-acetic acid, and carbon and nitrogen metabolism were also revealed, displaying overall trends of upregulation under HD. These findings provide a basis for identifying candidate genes related to planting density and could increase our molecular understanding of the effect of planting density on gene expression. [ABSTRACT FROM AUTHOR]

Despite knowledge that seagrass meadows are threatened by multiple global change stressors, significant gaps exist in current knowledge. In particular, little is known about the interactive effects of warming and eutrophication on seagrasses globally, or about responses of African seagrasses to global change, despite these ecosystem engineers providing critical goods and services to local livelihoods. Here, we report on laboratory experiment assessing the main and joint effects of warming and nutrient enrichment on Cape eelgrass (Zostera capensis) from the West coast of South Africa, in which morphological attributes, photosynthetic efficiency and elemental content were assessed. Results indicate that shoot density, leaf length, aboveground biomass and effective quantum yield were negatively impacted by both warming and nutrient enrichment. Growth rate, leaf density and leaf width decreased with increasing nutrient levels but not temperature. In addition, epiphytic fouling on seagrass leaves were enhanced by both warming and nutrient enrichment but with warming eliciting a greater response. Collectively, our findings indicate a stronger effect of enrichment on Z. capensis performance relative to warming, suggesting that the upper levels of coastal eutrophication upon which our experiment was based is likely a stronger stressor than warming. Our findings also highlight limited interaction between warming and nutrient enrichment on Z. capensis performance, suggesting that effects of these stressors are likely to be propagated individually and not interactively. Our findings raise awareness of susceptibility of Z. capensis to eutrophication and the need to manage nutrient inputs into coastal ecosystems to preserve meadows of this seagrass and the critical ecosystem functions they provide. [ABSTRACT FROM AUTHOR]

In this review, using the network analysis, based on the bibliometric data, collected from Web of Science Core Collection database, we followed the development of chlorophyll fluorescence research (CFR) during 1947-2018. We confirmed dramatic increase in diversity of CFR from late 90-ties and vigorous development of this discipline in the last ten years. They are parallel to an increase in number of research areas and institutions involved and were triggered by the accumulation of knowledge and methodological, technological, and communication advances, especially modern fluorimeters and fluorescence techniques. The network analysis of keywords and research areas confirmed CFR changed into modern, multidisciplinary, highly collaborative discipline, in which in spite of many 'core' disciplines as plant science, environmental sciences, agronomy/food science and technology, the promising, modern areas developed: biochemistry and molecular biology, remote sensing, and big data artificial intelligence method. [ABSTRACT FROM AUTHOR]

Cover Legend A fragment of pollen tetrads connected by viscin threads from butterfly‐pollinated Rhododendron fortunei. Courtesy of Hui‐Hui Feng & Shuang‐Quan Huang (Song et al., pp. 1150–1159). Read more about our covers in the 'Behind the cover' blog: newphytologist.org/behind-the-cover. [ABSTRACT FROM AUTHOR]

Training systems generally alter tree architecture, which modulates light microclimate within the canopy, for the purpose of improving photosynthetic efficiency and fruit quality. Gene expression quantification is one of the most important methods for exploring the molecular mechanisms underlying the influence of training systems on pear photosynthesis, and suitable reference genes for gene expression normalization are a prerequisite for this method. In this study, the expression stability of nine common and four novel candidate genes were evaluated in 14 different pear leaf samples in two training systems, including those at four developmental stages (training_period) and from different parts of the trees (training_space), using two distinct algorithms, geNorm and NormFinder. Our results revealed that SKD1 (Suppressor of K+ Transport Growth Defect1)/ YLS8 (Yellow Leaf Specific 8) and ARM (Armadillo) were the most stable single reference genes for the ‘training_period’ and ‘training_space’ subsets, respectively, although these single genes were not as stable as the optimal pairs of reference genes, SKD1+YLS8 and ARM+YLS8, respectively. Furthermore, the expression levels of the PpsAPX (Ascorbate peroxidase) gene showed that the arbitrary use of reference genes without previous testing could lead to misinterpretation of data. This work constitutes the first systematic analysis regarding the selection of superior reference genes in training system studies, facilitating the elucidation of gene function in pear and providing valuable information for similar studies in other higher plants. [ABSTRACT FROM AUTHOR]

• Explanations of leaf size variation commonly focus on water availability, yet leaf size also varies with latitude and elevation in environments where water is not strongly limiting. We provide the first conclusive test of a prediction of leaf energy balance theory that may explain this pattern: large leaves are more vulnerable to night-time chilling, because their thick boundary layers impede convective exchange with the surrounding air. • Seedlings of 15 New Zealand evergreens spanning 12-fold variation in leaf width were exposed to clear night skies, and leaf temperatures were measured with thermocouples. We then used a global dataset to assess several climate variables as predictors of leaf size in forest assemblages. • Leaf minus air temperature was strongly correlated with leaf width, ranging from -0.9 to -3.2°C in the smallest- and largest-leaved species, respectively. Mean annual temperature and frost-free period were good predictors of evergreen angiosperm leaf size in forest assemblages, but no climate variable predicted deciduous leaf size. • Although winter deciduousness makes large leaves possible in strongly seasonal climates, large-leaved evergreens are largely confined to frost-free climates because of their susceptibility to radiative cooling. Evergreen leaf size data can therefore be used to enhance vegetation models, and to infer palaeotemperatures from fossil leaf assemblages. [ABSTRACT FROM AUTHOR]

Keywords: carbon cycling; chilling tolerance; field phenotyping; global change; photosynthesis; Spartina; water-use efficiency EN carbon cycling chilling tolerance field phenotyping global change photosynthesis Spartina water-use efficiency 1034 1036 3 07/16/20 20200815 NES 200815 What inspired your interest in plant science? At that time, C SB 4 sb photosynthesis was considered exclusive to warm climates, but from my classes at Reading, it appeared to me that some plants of the northern European flora should be C SB 4 sb , based on evolutionary relationships. What was more significant was that not only was this a C SB 4 sb plant existing in a cool climate, but against all prior knowledge of C SB 4 sb photosynthesis, it was thriving in the British climate. [Extracted from the article]

Equatorial species may have less capacity to adjust to warmer temperatures because they have adapted to stable thermal conditions year-round compared to species from cooler climates (higher latitudes) where temperature fluctuates strongly among the seasons. Given that temperature responses of plants to warming are fundamental in any environment, how are plant function and metabolism linked to seasonal variations and climate? Understanding how temperature dependence of physiological processes is related to climate variation is critical to predict how species will adjust to warmer temperatures, what their thermal tolerances are, and ultimately lead to understanding how future species distributions may change. Plant carbon metabolism and climate change: elevated CO 2 and temperature impacts on photosynthesis, photorespiration and respiration. [Extracted from the article]

Background and Aims Setaria viridis is being promoted as a model C4 photosynthetic plant because it has a small genome (~515 Mb), a short life cycle (~60 d) and it can be transformed. Unlike other C4 grasses such as maize, however, there is very little information about how C4 leaf anatomy (Kranz anatomy) develops in S. viridis. As a foundation for future developmental genetic studies, we provide an anatomical and ultrastructural framework of early shoot development in S. viridis, focusing on the initiation of Kranz anatomy in seed leaves. Methods Setaria viridis seeds were germinated and divided into five stages covering development from the dry seed (stage S0) to 36 h after germination (stage S4). Material at each of these stages was examined using conventional light, scanning and transmission electron microscopy. Key Results Dry seeds contained three embryonic leaf primordia at different developmental stages (plastochron 1-3 primordia). The oldest (P3) leaf primordium possessed several procambial centres whereas P2 displayed only ground meristem. At the tip of P3 primordia at stage S4, C4 leaf anatomy typical of the malate dehydrogenasedependent nicotinamide dinucleotide phosphate (NADP-ME) subtype was evident in that vascular bundles lacked a mestome layer and were surrounded by a single layer of bundle sheath cells that contained large, centrifugally located chloroplasts. Two to three mesophyll cells separated adjacent vascular bundles and one mesophyll cell layer on each of the abaxial and adaxial sides delimited vascular bundles from the epidermis. Conclusions The morphological trajectory reported here provides a foundation for studies of gene regulation during early leaf development in S. viridis and a framework for comparative analyses with other C4 grasses. [ABSTRACT FROM AUTHOR]

Contents1018I.1018II.1019III.1022IV.1025V.1026VI.10291030References1030 Summary: Stomata are leaf epidermal structures consisting of two guard cells surrounding a pore. Changes in the aperture of this pore regulate plant water‐use efficiency, defined as gain of C by photosynthesis per leaf water transpired. Stomatal aperture is actively regulated by reversible changes in guard cell osmolyte content. Despite the fact that guard cells can photosynthesize on their own, the accumulation of mesophyll‐derived metabolites can seemingly act as signals which contribute to the regulation of stomatal movement. It has been shown that malate can act as a signalling molecule and a counter‐ion of potassium, a well‐established osmolyte that accumulates in the vacuole of guard cells during stomatal opening. By contrast, their efflux from guard cells is an important mechanism during stomatal closure. It has been hypothesized that the breakdown of starch, sucrose and lipids is an important mechanism during stomatal opening, which may be related to ATP production through glycolysis and mitochondrial metabolism, and/or accumulation of osmolytes such as sugars and malate. However, experimental evidence supporting this theory is lacking. Here we highlight the particularities of guard cell metabolism and discuss this in the context of the guard cells themselves and their interaction with the mesophyll cells. [ABSTRACT FROM AUTHOR]

Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C ( Vc,max.25 and Jmax.25, respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species., We measured photosynthetic CO2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska., The activation energies associated with the temperature response functions of Vc,max and Jmax were 17% lower than commonly used values. When scaled to 25°C, Vc,max.25 and Jmax.25 were two- to five-fold higher than the values used to parameterize current TBMs. This high photosynthetic capacity was attributable to a high leaf N content and the high fraction of N invested in Rubisco. Leaf-level modeling demonstrated that current parameterization of TBMs resulted in a two-fold underestimation of the capacity for leaf-level CO2 assimilation in Arctic vegetation., This study highlights the poor representation of Arctic photosynthesis in TBMs, and provides the critical data necessary to improve our ability to project the response of the Arctic to global environmental change. [ABSTRACT FROM AUTHOR]

The article discusses the highlights of the 17th International Congress on Photosynthesis Research--Photosynthesis in a Changing World, which was held in Maastricht, the Netherlands in August 2016. The event focused on topics including submolecular-scale biophysical details of energy transfer, basic chemistry of artificial photosynthesis, ecophysiology and crop physiology at whole leaf and whole plant.

C4 photosynthesis is a complex trait resulting from a series of anatomical and biochemical modifications to the ancestral C3 pathway. It is thought to evolve in a stepwise manner, creating intermediates with different combinations of C4-like components. Determining the adaptive value of these components is key to understanding how C4 photosynthesis can gradually assemble through natural selection. Here, we decompose the photosynthetic phenotypes of numerous individuals of the grass Alloteropsis semialata, the only species known to include both C3 and C4 genotypes. Analyses of δ13C, physiology and leaf anatomy demonstrate for the first time the existence of physiological C3-C4 intermediate individuals in the species. Based on previous phylogenetic analyses, the C3-C4 individuals are not hybrids between the C3 and C4 genotypes analysed, but instead belong to a distinct genetic lineage, and might have given rise to C4 descendants. C3 A. semialata, present in colder climates, likely represents a reversal from a C3-C4 intermediate state, indicating that, unlike C4 photosynthesis, evolution of the C3-C4 phenotype is not irreversible. [ABSTRACT FROM AUTHOR]

We measured a diverse range of foliar characteristics in shrub and tree species in temperate rainforest communities along a soil chronosequence (six sites from 8 to 120 000 years) and used multilevel model analysis to attribute the proportion of variance for each trait into genetic (G, here meaning species-level), environmental (E) and residual error components. We hypothesised that differences in leaf traits would be driven primarily by changes in soil nutrient availability during ecosystem progression and retrogression. Several leaf structural, chemical and gas-exchange traits were more strongly driven by G than E effects. For leaf mass per unit area (MA), foliar [N], net CO2 assimilation and dark respiration rates and foliar carbohydrate concentration, the G component accounted for 60-87% of the total variance, with the variability associated with plot, the E effect, much less important. Other traits, such as foliar [P] and N: P, displayed strong E and residual effects. Analyses revealed significant reductions in the slopes of G-only bivariate relationships when compared with raw relationships, indicating that a large proportion of trait-trait relationships is species based, and not a response to environment per se. This should be accounted for when assessing the mechanistic basis for using such relationships in order to make predictions of responses of plants to short-term environmental change. [ABSTRACT FROM AUTHOR]

Background: RLSB, an S-1 domain RNA binding protein of Arabidopsis, selectively binds rbcL mRNA and co-localizes with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) within chloroplasts of C3 and C4 plants. Previous studies using both Arabidopsis (C3) and maize (C4) suggest RLSB homologs are post-transcriptional regulators of plastid-encoded rbcL mRNA. While RLSB accumulates in all Arabidopsis leaf chlorenchyma cells, in C4 leaves RLSB-like proteins accumulate only within Rubisco-containing bundle sheath chloroplasts of Kranz-type species, and only within central compartment chloroplasts in the single cell C4 plant Bienertia. Our recent evidence implicates this mRNA binding protein as a primary determinant of rbcL expression, cellular localization/compartmentalization, and photosynthetic function in all multicellular green plants. This study addresses the hypothesis that RLSB is a highly conserved Rubisco regulatory factor that occurs in the chloroplasts all higher plants. Results: Phylogenetic analysis has identified RLSB orthologs and paralogs in all major plant groups, from ancient liverworts to recent angiosperms. RLSB homologs were also identified in algae of the division Charophyta, a lineage closely related to land plants. RLSB-like sequences were not identified in any other algae, suggesting that it may be specific to the evolutionary line leading to land plants. The RLSB family occurs in single copy across most angiosperms, although a few species with two copies were identified, seemingly randomly distributed throughout the various taxa, although perhaps correlating in some cases with known ancient whole genome duplications. Monocots of the order Poales (Poaceae and Cyperaceae) were found to contain two copies, designated here as RLSB-a and RLSB-b, with only RLSB-a implicated in the regulation of rbcL across the maize developmental gradient. Analysis of microsynteny in angiosperms revealed high levels of conservation across eudicot species and for both paralogs in grasses, highlighting the possible importance of maintaining this gene and its surrounding genomic regions. Conclusions: Findings presented here indicate that the RLSB family originated as a unique gene in land plant evolution, perhaps in the common ancestor of charophytes and higher plants. Purifying selection has maintained this as a highly conserved single- or two-copy gene across most extant species, with several conserved gene duplications. Together with previous findings, this study suggests that RLSB has been sustained as an important regulatory protein throughout the course of land plant evolution. While only RLSB-a has been directly implicated in rbcL regulation in maize, RLSB-b could have an overlapping function in the co-regulation of rbcL, or may have diverged as a regulator of one or more other plastid-encoded mRNAs. This analysis confirms that RLSB is an important and unique photosynthetic regulatory protein that has been continuously expressed in land plants as they emerged and diversified from their ancient common ancestor. [ABSTRACT FROM AUTHOR]

We introduce the Polar Vegetation Photosynthesis and Respiration Model (PolarVPRM), a remote-sensing-based approach for generating accurate, high-resolution ( ≥1 km2, 3 hourly) estimates of net ecosystem CO2 exchange (NEE). PolarVPRM simulates NEE using polarspecific vegetation classes, and by representing high-latitude influences on NEE, such as the influence of soil temperature on subnivean respiration. We present a description, validation and error analysis (first-order Taylor expansion) of PolarVPRM, followed by an examination of per-pixel trends (2001-2012) in model output for the North American terrestrial region north of 55° N. PolarVPRM was validated against eddy covariance (EC) observations from nine North American sites, of which three were used in model calibration. Comparisons of EC NEE to NEE from three models indicated that PolarVPRM displayed similar or better statistical agreement with eddy covariance observations than existing models showed. Trend analysis (2001-2012) indicated that warming air temperatures and drought stress in forests increased growing season rates of respiration, and decreased rates of net carbon uptake by vegetation when air temperatures exceeded optimal temperatures for photosynthesis. Concurrent increases in growing season length at Arctic tundra sites allowed for increases in photosynthetic uptake over time by tundra vegetation. PolarVPRM estimated that the North American high-latitude region changed from a carbon source (2001-2004) to a carbon sink (2005-2010) to again a source (2011-2012) in response to changing environmental conditions. [ABSTRACT FROM AUTHOR]

This paper describes how, from the early twentieth century, and especially in the early Cold War era, the plant physiologists considered their discipline ideally suited among all the plant sciences to study and explain biological functions and processes, and ranked their discipline among the dominant forms of the biological sciences. At their apex in the late-1960s, the plant physiologists laid claim to having discovered nothing less than the “basic laws of physiology.” This paper unwraps that claim, showing that it emerged from the construction of monumental big science laboratories known as phytotrons that gave control over the growing environment. Control meant that plant physiologists claimed to be able to produce a standard phenotype valid for experimental biology. Invoking the standards of the physical sciences, the plant physiologists heralded basic biological science from the phytotronic produced phenotype. In the context of the Cold War era, the ability to pursue basic science represented the highest pinnacle of standing within the scientific community. More broadly, I suggest that by recovering the history of an underappreciated discipline, plant physiology, and by establishing the centrality of the story of the plant sciences in the history of biology can historians understand the massive changes wrought to biology by the conceptual emergence of the molecular understanding of life, the dominance of the discipline of molecular biology, and the rise of biotechnology in the 1980s. [ABSTRACT FROM AUTHOR]

This article comments on: [ABSTRACT FROM AUTHOR]

Growth light intensities largely determine photosynthesis, biomass, and grain yield of cereal crops. To explore the genetic basis of light responses of biomass and photosynthetic parameters in wheat ( Triticum aestivum L.), a quantitative trait locus (QTL) analysis was carried out in a doubled haploid (DH) population grown in low light (LL), medium light (ML), and high light (HL), respectively. The results showed that the wheat seedlings grown in HL produced more biomass with lower total chlorophyll content (Chl), carotenoid content, and maximum photochemical efficiency of photosystem II ( Fv/Fm) while the wheat seedlings grown in LL produced less biomass with higher Chl compared with those grown in ML. In total, 48 QTLs were identified to be associated with the investigated parameters in relation to growth light intensities. These QTLs were mapped to 15 chromosomes which individually explained 6.3%-36.0% of the phenotypic variance, of which chromosomes 3A, 1D, and 6B were specifically involved in LL response, 5D and 7A specifically involved in ML response, and 4B specifically involved in HL response. Several light-responsive QTLs were co-located with QTLs for photosynthetic parameters, biomass, and grain weight under various conditions which may provide new hints to uncover the genetic control of photosynthesis, biomass, and grain weight. [ABSTRACT FROM AUTHOR]

Because of the complexity of plant responses to water deficit, researchers have attempted to identify simplified models to understand critical aspects of the problem by searching for single indicators that would enable evaluations of the effects of environmental changes on the entire plant. However, this reductionist approach, which is often used in plant sciences, makes it difficult to distinguish systemic emergent behaviours. Currently, a new class of models and epistemology have called attention to the fundamental properties of complex systems. These properties, termed 'emergent', are observed at a large scale of the system (top hierarchical level) but cannot be observed or inferred from smaller scales of observation in the same system. We propose that multivariate statistical analysis can provide a suitable tool to quantify global responses to water deficit, allowing a specific and partially quantitative assessment of emergent properties. Based on an experimental study, our results showed that the classical approach of the individual analysis of different data sets might provide different interpretations for the observed effects of water deficit. These results support the hypothesis that a cross-scale multivariate analysis is an appropriate method to establish models for systemic understanding of the interactions between plants and their changing environment. [ABSTRACT FROM AUTHOR]

Ginseng ( Panax ginseng) is a typical perennial shade plant. Aim of this study was to investigate the effects of exogenous hormones on photosynthesis of P. ginseng. At different growth stages, the aerial parts of P. ginseng plants were cut at the stem base and they were inserted into the nutrient solutions containing different exogenous hormones. Then the leaf photosynthesis and water absorbing capacity (absorbing water mass) of the excised plants were measured. The results showed that exogenous abscisic acid (ABA) decreased significantly net photosynthetic rate ( P), stomatal conductance, transpiration rate, and absorbed water mass of excised P. ginseng at all growth stages, while both cytokinin (CTK) and indole-3-acetic acid (IAA) enhanced those parameters. Comparing different growth stages, ABA caused more severe inhibition of leaf photosynthesis at the early growth stage, while CTK and IAA showed significant enhancement of leaf photosynthesis at later growth stage. ABA reduced highly intercellular CO concentration of P. ginseng at the flowering and green fruit stages, but it had only a small effect at red fruit early and red fruit stages. During the early growth stage, the inhibitory effect of ABA on leaf P might be caused mainly due to the stomatal limitation. However, the reason for this reduction was complex at the later growth stage and it included stomatal and other factors. [ABSTRACT FROM AUTHOR]

In many plant species that remain leafless part of the year, CO fixation occurring in green stems represents an important carbon gain. Traditionally, a distinction has been made between stem photosynthesis and corticular photosynthesis. All stem photosynthesis is, sensu stricto, cortical, since it is carried out largely by the stem cortex. We proposed the following nomenclature: stem net photosynthesis (SNP), which includes net CO fixation by stems with stomata in the epidermis and net corticular CO fixation in suberized stems, and stem recycling photosynthesis (SRP), which defines CO ling in suberized stems. The proposed terms should reflect differences in anatomical and physiological traits. SNP takes place in the chlorenchyma below the epidermis with stomata, where the net CO uptake occurs, and it resembles leaf photosynthesis in many characteristics. SRP is found in species where the chlorenchyma is beneath a well-developed stomata-free periderm and where reassimilation of internally respired CO occurs. SNP is common in plants from desert ecosystems, rates reaching up to 60% of the leaf photosynthetic rate. SRP has been demonstrated in trees from temperate forests and it offsets partially a carbon loss by respiration of stem nonphotosynthetic tissues. Reassimilation can vary between 7 and 123% of respired CO, the latter figure implying net CO uptake from the atmosphere. Both types of stem photosynthesis contribute positively to the carbon economy of the species, in which they occur; they are advantageous to the plant because they allow the maintenance of physiological activity during stress, an increase of integrated water use efficiency, and they provide the carbon source used in the production of new organs. [ABSTRACT FROM AUTHOR]

Anoectochilus roxburghii was grown under different shade treatments–50%, 30%, 20%, and 5% of natural irradiance–to evaluate its photosynthetic characteristics, chloroplast ultrastructure, and physiology. The highest net photosynthetic rates and stomatal conductance were observed under 30% irradiance, followed in descending order by 20%, 5%, and 50% treatments. As irradiance decreased from 50% to 30%, electron transport rate and photochemical quenching increased, while non-photochemical quenching indexes declined. Reductions in irradiance significantly increased Chl a and Chl b contents and decreased Chl a/b ratios. Chloroplast ultrastructure generally displayed the best development in leaves subjected to 30% irradiance. Under 50% irradiance, leaf protein content remained relatively stable during the first 20 days of treatment, and then increased rapidly. The highest peroxidase and superoxide dismutase levels, and the lowest catalase activities, were observed in plants subjected to the 50% irradiance treatment. Soluble sugar and malondialdehyde contents were positively correlated with irradiance levels. Modulation of chloroplast development, accomplished by increasing the number of thylakoids and grana containing photosynthetic pigments, is an important shade tolerance mechanism in A. roxburghii. [ABSTRACT FROM AUTHOR]

Prior studies on preferences of native herbivores for native or exotic plants have tested both the enemy release hypothesis and the biotic resistance hypothesis and have reported inconsistent results. The different levels of resistance of native and exotic plants to native herbivores could resolve this controversy, but little attention has been paid to this issue. In this study, we investigated population performance, photosynthesis, leaf nitrogen concentration, and the constitutive and induced resistances of the successful invasive plant, Alternanthera philoxeroides, and its native congener, Alternanthera sessilis, in the presence of three population densities of the grasshopper, Atractomorpha sinensis. When the grasshopper was absent, leaf biomass, total biomass, photosynthesis, and leaf nitrogen concentration of A. philoxeroides were higher than those of A. sessilis. However, the morphological and physiological performances of A. philoxeroides were all decreased more intensively than A. sessilis after herbivory by grasshoppers. Especially as the concentrations of constitutive lignin and cellulose in leaf of A. philoxeroides were higher than A. sessilis, A. philoxeroides exhibited increased leaf lignin concentration to reduce its palatability only at severe herbivore load, whereas, leaf lignin, cellulose, and polyphenolic concentrations of A. sessilis all increased with increasing herbivory pressure, and cellulose and polyphenolic concentrations were higher in A. sessilis than in A. philoxeroides after herbivory. Our study indicated that the capability of the invasive plant to respond to native insect damage was lower than the native plant, and the invasive plant was suppressed more intensively than its native congener by the native insect. Our results support the biotic resistance hypothesis and suggest that native herbivores can constrain the abundance and reduce the adverse effects of invasive species. [ABSTRACT FROM AUTHOR]

The article presents a study which aims at analyzing the life on the planet Venus. It discusses about panoramic images used by the researchers which are focused on the flora and fauna present on Venus. Various characteristics of Venus are presented including waterless land, volcanoes and unusual photosynthesis. It also informs about the presence of amisadas on Venus whose spatial resolution was far from the camera.