scholarly journals LEAF ANATOMY CHARACTERIZATION OF FOUR Apochloa SPECIES: A C3 GENUS RELATED TO EVOLUTION OF C4 PATHWAY IN GRASSES

2020 ◽  
Vol 26 (1) ◽  
pp. 12-18
Author(s):  
Ane Marcela das Chagas Mendonça ◽  
Pedro Lage Viana ◽  
João Paulo Rodrigues Alves Delfino Barbosa
Keyword(s):  
Leaf Anatomy ◽  
C4 Photosynthesis ◽  
Water Status ◽  
Bundle Sheath ◽  
C3 Plants ◽  
Plant Water ◽  
Kranz Anatomy ◽  
C4 Pathway ◽  
Photosynthesis Pathway

Leaf anatomy characteristics provide important evidences about the transition between C3 and C4 pathways. The C4 photosynthesis pathway allowed to reduce the C3 photorespiratory rate, concentrating CO2 around the Rubisco site and using structures and machinery already presented in C3 plants. In monocots, it is observed a high number of C4 lineages, most of them phylogenetically related to C3 groups. The genus Apochloa (C3), subtribe Arthropogoninae, is related to two C4 genera Coleataenia and Cyphonanthus. The aim of this study was to evaluate four Apochloa species in order to establish anatomical characteristics related to the evolution of C4 pathway in this group. By means of transverse sections fully expanded leaves of A. euprepes, A. lorea, A. molinioides, and A. poliophylla were collected and the characteristics of the mesophyll (M) and bundle sheath (BS) cells were determined. These species showed a rustic Kranz anatomy with enlarged and radial arranged BS cells, which have few organelles organized in a centrifugal position. Although the modifications of BS cells are probably related to the maintenance of plant water status, we also discuss the evolution for the establishment of C4 photosynthesis in the related C4 genera.

scholarly journals Challenges and Approaches to Crop Improvement Through C3-to-C4 Engineering

2021 ◽  
Vol 12 ◽  
Author(s):  
Hongchang Cui
Keyword(s):  
Photosynthetic Efficiency ◽  
C4 Photosynthesis ◽  
Crop Improvement ◽  
Bundle Sheath ◽  
C4 Plants ◽  
System Level ◽  
C3 Plants ◽  
World Population ◽  
Kranz Anatomy ◽  
The Past

With a rapidly growing world population and dwindling natural resources, we are now facing the enormous challenge of increasing crop yields while simultaneously improving the efficiency of resource utilization. Introduction of C4 photosynthesis into C3 crops is widely accepted as a key strategy to meet this challenge because C4 plants are more efficient than C3 plants in photosynthesis and resource usage, particularly in hot climates, where the potential for productivity is high. Lending support to the feasibility of this C3-to-C4 engineering, evidence indicates that C4 photosynthesis has evolved from C3 photosynthesis in multiple lineages. Nevertheless, C3-to-C4 engineering is not an easy task, as several features essential to C4 photosynthesis must be introduced into C3 plants. One such feature is the spatial separation of the two phases of photosynthesis (CO2 fixation and carbohydrate synthesis) into the mesophyll and bundle sheath cells, respectively. Another feature is the Kranz anatomy, characterized by a close association between the mesophyll and bundle sheath (BS) cells (1:1 ratio). These anatomical features, along with a C4-specific carbon fixation enzyme (PEPC), form a CO2-concentration mechanism that ensures a high photosynthetic efficiency. Much effort has been taken in the past to introduce the C4 mechanism into C3 plants, but none of these attempts has met with success, which is in my opinion due to a lack of system-level understanding and manipulation of the C3 and C4 pathways. As a prerequisite for the C3-to-C4 engineering, I propose that not only the mechanisms that control the Kranz anatomy and cell-type-specific expression in C3 and C4 plants must be elucidated, but also a good understanding of the gene regulatory network underlying C3 and C4 photosynthesis must be achieved. In this review, I first describe the past and current efforts to increase photosynthetic efficiency in C3 plants and their limitations; I then discuss a systems approach to tackling down this challenge, some practical issues, and recent technical innovations that would help us to solve these problems.

Physiological, anatomical and biochemical characterisation of photosynthetic types in genus Cleome (Cleomaceae)

2007 ◽  
Vol 34 (4) ◽  
pp. 247 ◽  
Author(s):  
Elena V. Voznesenskaya ◽  
Nuria K. Koteyeva ◽  
Simon D. X. Chuong ◽  
Alexandra N. Ivanova ◽  
João Barroca ◽  
...  
Keyword(s):  
Leaf Anatomy ◽  
C4 Photosynthesis ◽  
C3 Plants ◽  
Intermediate Species ◽  
Δ13c Values ◽  
C4 Species ◽  
Cleome Gynandra ◽  
The Family ◽  
C3 Species ◽  
C4 Pathway

C4 photosynthesis has evolved many times in 18 different families of land plants with great variation in leaf anatomy, ranging from various forms of Kranz anatomy to C4 photosynthesis occurring within a single type of photosynthetic cell. There has been little research on photosynthetic typing in the family Cleomaceae, in which only one C4 species has been identified, Cleome gynandra L. There is recent interest in selecting and developing a C4 species from the family Cleomaceae as a model C4 system, since it is the most closely related to Arabidopsis, a C3 model system (Brown et al. 2005). From screening more than 230 samples of Cleomaceae species, based on a measure of the carbon isotope composition (δ13C) in leaves, we have identified two additional C4 species, C. angustifolia Forssk. (Africa) and C. oxalidea F.Muell. (Australia). Several other species have δ13C values around –17‰ to –19‰, suggesting they are C4-like or intermediate species. Eight species of Cleome were selected for physiological, anatomical and biochemical analyses. These included C. gynandra, a NAD–malic enzyme (NAD–ME) type C4 species, C. paradoxa R.Br., a C3–C4 intermediate species, and 6 others which were characterised as C3 species. Cleome gynandra has C4 features based on low CO2 compensation point (Γ), C4 type δ13C values, Kranz-type leaf anatomy and bundle sheath (BS) ultrastructure, presence of C4 pathway enzymes, and selective immunolocalisation of Rubisco and phosphoenolpyruvate carboxylase. Cleome paradoxa was identified as a C3–C4 intermediate based on its intermediate Γ (27.5 μmol mol–1), ultrastructural features and selective localisation of glycine decarboxylase of the photorespiratory pathway in mitochondria of BS cells. The other six species are C3 plants based on Γ, δ13C values, non-Kranz leaf anatomy, and levels of C4 pathway enzymes (very low or absent) typical of C3 plants. The results indicate that this is an interesting family for studying the genetic basis for C4 photosynthesis and its evolution from C3 species.

scholarly journals C4 photosynthesis with Kranz anatomy evolved in the Oryza coarctata Roxb

2020 ◽  
Author(s):  
Soni Chowrasia ◽  
Tapan Kumar Mondal
Keyword(s):  
C4 Photosynthesis ◽  
Expression Patterns ◽  
Bundle Sheath ◽  
Ultrastructural Observation ◽  
Mesophyll Cells ◽  
Potential Donor ◽  
Kranz Anatomy ◽  
Vein Density ◽  
Bundle Sheath Cells ◽  
Sheath Cells

AbstractThe C4 cycle is a complex biochemical pathway that has been evolved in plants to deal with the adverse environmental conditions. Mostly C4 plants grow in arid, water-logged area or poor nutrient habitats. Wild species, Oryza coarctata (genome type KKLL; chromosome number (4x) =48, genome size 665 Mb) belongs to the genus of Oryza which thrives well under high saline as well as submerged conditions. Here, we report for the first time that O. coarctata is a C4 plant by observing the increased biomass growth, morphological features such as vein density, anatomical features including ultrastuctural characteristics as well as expression patterns of C4 related genes. Leaves of O. coarctata have higher vein density and possess Kranz anatomy. The ultrastructural observation showed chloroplast dimorphism i.e. presence of agranal chloroplasts in bundle sheath cells whereas, mesophyll cells contain granal chloroplasts. The cell walls of bundle sheath cells contain tangential suberin lamella. The transcript level of C4 specific genes such as phosphoenolpyruvate carboxylase, pyruvate orthophosphate dikinase, NADP-dependent malic enzyme and malate dehydrogenase was higher in leaves of O. coarctata compare to high yielding rice cultivar (IR-29). These anatomical, ultra structural as well as molecular changes in O. coarctata for C4 photosynthesis adaptation might be might be due to its survival in wide diverse condition from aquatic to saline submerged condition. Being in the genus of Oryza, this plant could be potential donor for production of C4 rice in future through conventional breeding, as successful cross with rice has already been reported.

Modelling metabolic evolution on phenotypic fitness landscapes: a case study on C4 photosynthesis

2015 ◽  
Vol 43 (6) ◽  
pp. 1172-1176 ◽  
Author(s):  
David Heckmann
Keyword(s):  
Structural Changes ◽  
Crop Yields ◽  
C4 Photosynthesis ◽  
Fitness Landscape ◽  
Fitness Landscapes ◽  
C3 Plants ◽  
Metabolic Systems ◽  
C4 Pathway ◽  
Evolutionary Trajectories ◽  
Phenotypic Fitness

How did the complex metabolic systems we observe today evolve through adaptive evolution? The fitness landscape is the theoretical framework to answer this question. Since experimental data on natural fitness landscapes is scarce, computational models are a valuable tool to predict landscape topologies and evolutionary trajectories. Careful assumptions about the genetic and phenotypic features of the system under study can simplify the design of such models significantly. The analysis of C4 photosynthesis evolution provides an example for accurate predictions based on the phenotypic fitness landscape of a complex metabolic trait. The C4 pathway evolved multiple times from the ancestral C3 pathway and models predict a smooth ‘Mount Fuji’ landscape accordingly. The modelled phenotypic landscape implies evolutionary trajectories that agree with data on modern intermediate species, indicating that evolution can be predicted based on the phenotypic fitness landscape. Future directions will have to include structural changes of metabolic fitness landscape structure with changing environments. This will not only answer important evolutionary questions about reversibility of metabolic traits, but also suggest strategies to increase crop yields by engineering the C4 pathway into C3 plants.

scholarly journals Changes in the plasmodesma structure and permeability at the bundle sheath and mesophyll interface during the maize C4 leaf development

2020 ◽  
Author(s):  
Peng Gao ◽  
Baijuan Du ◽  
Pinghua Li ◽  
Byung-Ho Kang
Keyword(s):  
Cell Wall ◽  
Organic Acids ◽  
Molecular Diffusion ◽  
C4 Photosynthesis ◽  
Solute Concentration ◽  
Bundle Sheath ◽  
Solute Diffusion ◽  
Cell Wall Modification ◽  
Maize Leaf ◽  
Kranz Anatomy

AbstractPlasmodesmata are intercellular channels that facilitate molecular diffusion between neighboring plant cells. The development and functions of plasmodesmata are controlled by multiple intra- and intercellular signaling pathways. Plasmodesmata are critical for dual-cell C4 photosynthesis in maize because plasmodesmata at the mesophyll and bundle sheath interface mediate exchange of CO2-carrying organic acids. We examined developmental profiles of plasmodesmata and chloroplasts in the maize leaf from young cells in the base to mature cell in the tip using microscopy approaches. Young mesophyll and bundle sheath cells in the leaf base had proplastids, and their plasmodesmata were simple, devoid of cytoplasmic sleeves. In maturing cells where Kranz anatomy and dimorphic chloroplasts were evident, we observed extensive remodeling of plasmodesmata that included acquisition of an electron-dense ring on the mesophyll side and cytoplasmic sleeves on the bundle sheath side. Interestingly, the changes in plasmodesmata involved a drop in symplastic dye mobility and suberin accumulation in the cell wall, implying a more stringent mesophyll-bundle sheath transport. We compared kinetics of the plasmodesmata and the cell wall modification in wildtype leaves with leaves from ppdk and dct2 mutants with defective C4 pathways. Plasmodesmata development, symplastic transport inhibition, and cell wall suberization were accelerated in the mutant lines, probably due to the aberrant C4 cycle. Transcriptomic analyses of the mutants confirmed the expedited changes in the cell wall. Our results suggest that a regulatory machinery at the mesophyll-bundle sheath boundary suppresses erroneous flux of C4 metabolites in the maize leaf.Significance StatementPlasmodesmata in the maize Kranz anatomy mediate the exchange of organic acids between mesophyll and bundle sheath. Since solute diffusion through plasmodesmata is governed by solute concentration gradients, a balanced distribution of C4 metabolites is critical for concentration of CO2 in the bundle sheath. Plasmodesmata bridging the mesophyll and bundle sheath cytoplasm have a cylindrical cavity, which can facilitate molecular movements, and a valve-like attachment. Construction of the sophisticated plasmodesmata was linked to C4 photosynthesis, and plasmodesmata assembly finished more rapidly in maize mutants with defective C4 pathways than in wild-type plants. These results suggest that the specialized plasmodesmata contribute to controlled transport of C4 metabolites.

C4 rice: a challenge for plant phenomics

2009 ◽  
Vol 36 (11) ◽  
pp. 845 ◽  
Author(s):  
Robert T. Furbank ◽  
Susanne von Caemmerer ◽  
John Sheehy ◽  
Gerry Edwards
Keyword(s):  
C4 Photosynthesis ◽  
Oryza Sativa L ◽  
Yield Potential ◽  
C3 Plants ◽  
Or Efficiency ◽  
C4 Pathway ◽  
Large Populations ◽  
Plant Phenomics ◽  
Research Consortium ◽  
Sorghum Bicolor L

There is now strong evidence that yield potential in rice (Oryza sativa L.) is becoming limited by ‘source’ capacity, i.e. photosynthetic capacity or efficiency, and hence the ability to fill the large number of grain ‘sinks’ produced in modern varieties. One solution to this problem is to introduce a more efficient, higher capacity photosynthetic mechanism to rice, the C4 pathway. A major challenge is identifying and engineering the genes necessary to install C4 photosynthesis in rice. Recently, an international research consortium was established to achieve this aim. Central to the aims of this project is phenotyping large populations of rice and sorghum (Sorghum bicolor L.) mutants for ‘C4-ness’ to identify C3 plants that have acquired C4 characteristics or revertant C4 plants that have lost them. This paper describes a variety of plant phenomics approaches to identify these plants and the genes responsible, based on our detailed physiological knowledge of C4 photosynthesis. Strategies to asses the physiological effects of the installation of components of the C4 pathway in rice are also presented.

Evolutionary transition from C3 to C4 photosynthesis and the route to C4 rice

Biologia ◽  
2013 ◽  
Vol 68 (4) ◽  
Author(s):  
Zheng Liu ◽  
Ning Sun ◽  
Shangjun Yang ◽  
Yanhong Zhao ◽  
Xiaoqin Wang ◽  
...  
Keyword(s):  
C4 Photosynthesis ◽  
C3 Plants ◽  
Hydraulic Systems ◽  
Leaf Architecture ◽  
Evolutionary Trajectory ◽  
Bisphosphate Carboxylase ◽  
Bundle Sheath Cells ◽  
C4 Pathway ◽  
C4 Evolution ◽  
C4 Enzymes

AbstractCompared with C3 plants, C4 plants possess a mechanism to concentrate CO2 around the ribulose-1,5-bisphosphate carboxylase/oxygenase in chloroplasts of bundle sheath cells so that the carboxylation reaction work at a much more efficient rate, thereby substantially eliminate the oxygenation reaction and the resulting photorespiration. It is observed that C4 photosynthesis is more efficient than C3 photosynthesis under conditions of low atmospheric CO2, heat, drought and salinity, suggesting that these factors are the important drivers to promote C4 evolution. Although C4 evolution took over 66 times independently, it is hypothesized that it shared the following evolutionary trajectory: 1) gene duplication followed by neofunctionalization; 2) anatomical and ultrastructral changes of leaf architecture to improve the hydraulic systems; 3) establishment of two-celled photorespiratory pump; 4) addition of transport system; 5) co-option of the duplicated genes into C4 pathway and adaptive changes of C4 enzymes. Based on our current understanding on C4 evolution, several strategies for engineering C4 rice have been proposed to increase both photosynthetic efficiency and yield significantly in order to avoid international food crisis in the future, especially in the developing countries. Here we summarize the latest progresses on the studies of C4 evolution and discuss the strategies to introduce two-celled C4 pathway into rice.

Are crassulacean acid metabolism and C4 photosynthesis incompatible?

2002 ◽  
Vol 29 (6) ◽  
pp. 775 ◽  
Author(s):  
Rowan F. Sage
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
C4 Photosynthesis ◽  
Bundle Sheath ◽  
C4 Plants ◽  
Cam Plants ◽  
Bundle Sheath Cells ◽  
C4 Pathway ◽  
Cam Species ◽  
Cam Photosynthesis

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Despite sharing a similar metabolism, crassulacean acid metabolism (CAM) and C4 photosynthesis are not known to occur in identical species, with the exception of Portulaca spp. In Portulaca, C4 and weak CAM photosynthesis occur in distinct regions of the leaf, rather than in the same cells. This is in marked contrast to the situation in most CAM species where C3 and CAM photosynthesis are active in the same cell over the course of a day and growing season. The lack of CAM and C4 photosynthesis in identical cells of a plant indicates these photosynthetic pathways are incompatible. Incompatibilities between CAM and C4 photosynthesis could have a number of biochemical, anatomical and evolutionary explanations. Biochemical incompatibilities could result from the requirement for spatial separation of C3 and C4 phases in C4 plants versus temporal separation in CAM plants. In C4 plants, regulatory systems coordinate mesophyll and bundle sheath metabolism, with light intensity being the major environmental signal. In CAM plants, a circadian oscillator coordinates day and night phases of CAM. The requirement for rapid intercellular transport in C4 plants may be incompatible with the intracellular transport and storage needs of CAM. For example, the large vacuole required for malate storage in CAM could impede metabolite diffusion between mesophyll and bundle sheath cells in C4 plants. Anatomical barriers could also exist because both CAM and the C4 pathway require distinct leaf anatomies for efficient function. Efficient function of the C4 pathway generally requires an outer layer of cells specialized for phosphoenolpyruvate (PEP) carboxylation and regeneration and an inner layer for CO2 accumulation and refixation, while CAM species require enlarged vacuoles and tight cell packing. In evolutionary terms, barriers preventing CAM and C4 photosynthesis in the same species may be the initial steps in the respective evolutionary pathways from C3 ancestors. The first steps in C4 photosynthesis are related to scavenging photorespiratory CO2 via localization of glycine decarboxylase in the bundle sheath cells. The initial steps in CAM evolution are associated with the scavenging of respiratory CO2 at night by PEP carboxylation. In each, simplified versions of the specialized anatomy may need to be present for the evolutionary sequence to begin. For C4 evolution, enhanced bundle sheath size may be required in C3 ancestors; for CAM evolution, succulence may be required. Thus, before CAM or C4 photosynthesis began to evolve, the outcome of the evolutionary experiment may have been predetermined.

scholarly journals Accelerated remodeling of the mesophyll-bundle sheath interface in the maize C4 cycle mutant leaves

2021 ◽  
Author(s):  
Peng Gao ◽  
Pengfei Wang ◽  
Baijuan Du ◽  
Pinghua Li ◽  
Byung-Ho Kang
Keyword(s):  
Cell Wall ◽  
Organic Acids ◽  
C4 Photosynthesis ◽  
Bundle Sheath ◽  
Wild Type ◽  
Symplastic Transport ◽  
Maize Leaf ◽  
Kranz Anatomy ◽  
Chloroplast Differentiation ◽  
Kinetics Of

Abstract C4 photosynthesis in the maize leaf involves the exchange of organic acids between mesophyll (M) and the bundle sheath (BS) cells. The transport is mediated by plasmodesmata embedded in the suberized cell wall. We examined the maize Kranz anatomy with a focus on the plasmodesma and cell wall suberization with microscopy methods. In the young leaf zone where M and BS cells had indistinguishable proplastids, plasmodesmata were simple and no suberin was detected. In leaf zones where dimorphic chloroplasts were evident, the plasmodesma acquired sphincter and cytoplasmic sleeves, and suberin was discerned. These modifications were accompanied by a drop in symplastic dye mobility at the M-BS boundary. We compared the kinetics of chloroplast differentiation and the modifications in M-BS connectivity in ppdk and dct2 mutants where C4 cycle is affected. The rate of chloroplast diversification did not alter, but plasmodesma remodeling, symplastic transport inhibition, and cell wall suberization were observed from younger leaf zone in the mutants than in wild type. Our results indicate that inactivation of the C4 genes accelerated the changes in the M-BS interface and the reduced permeability suggests that symplastic transport between M and BS could be gated probably for suppressing erroneous flux of C4 metabolites.

Sign in / Sign up

Export Citation Format

Share Document