Kranz Leaf Anatomy Research Articles

(2797) Proposal to reject the name Chenopodium pallidum (Chenopodiaceae / Amaranthaceae sensu APG)

(2797) Proposal to reject the name <i>Chenopodium pallidum</i> (<i>Chenopodiaceae</i> / <i>Amaranthaceae</i> sensu <scp>APG</scp>)

Corrigenda to “Taxonomic revision of Chenopodiaceae in Nepal” [Phytotaxa 191: 10–44. 2014

The first treatment of the family Chenopodiaceae for the flora of Nepal (Central and Eastern Himalaya) has been recently published (Sukhorukov &amp; Kushunina 2014). However, after a detailed investigation of original material concerning Chenopodium pallidum Moquin-Tandon (1840: 30), which is a part of Jacquemont’s collection from India (Herbarium P), we can state that all these specimens indeed belong to Atriplex Linnaeus (1753: 1052). The morphological differences between Atriplex and Chenopodium Linnaeus (1753: 218) are clear in mature plants only, whereas the plants in the type material were gathered in vegetative or early blooming stage (with flower buds only). This explains why the specimens have remained misidentified for such a long time. The characters which support our statement are: (1) Kranz leaf anatomy, which is typical of many Atriplex species (Sukhorukov 2006) placed into the large ‘C4-clade’ (Kadereit et al. 2010), but never observed in Chenopodium, (2) unisexual flowers (only male flower buds were found, because female flowers are absent at early blooming stage) which of all Chenopodieae in its current circumscription are present only in Atriplex (Sukhorukov &amp; Zhang 2013). The “Eastern India” (Fr.: “Indes Orientales” after Jacquemont, 1834), where the plants were collected, applies to the territories of present-day West Bengal, Uttar Pradesh, Delhi, Rajasthan (northern part), Uttarakhand, Himachal Pradesh, Jammu &amp; Kashmir, Punjab (India, Pakistan), and bordering parts of Xizang (China). Only some Atriplex species with Kranz leaf anatomy occur in this region (Zhu et al. 2003, Klimeš &amp; Dickoré 2005, Sukhorukov 2006), such as: A. centralasiatica Iljin (1936: 124), A. pamirica Iljin (1936: 124), and A. schugnanica Iljin (1936: 123). However, the plants known as A. schugnanica are the best match to the Jacquemont’s specimens due to aphyllous or bracteose (not leafy) inflorescence. According to Art. 11 of ICN (McNeill et al. 2012), the name Chenopodium pallidum appears to be an older name at specific rank for Atriplex schugnanica Iljin (1936: 123), and thus a new combination is proposed in the present paper. Besides, new Chenopodium species, previously named Chenopodium pallidum, is described from Nepal.

C4GEM, a genome-scale metabolic model to study C4 plant metabolism.

Leaves of C(4) grasses (such as maize [Zea mays], sugarcane [Saccharum officinarum], and sorghum [Sorghum bicolor]) form a classical Kranz leaf anatomy. Unlike C(3) plants, where photosynthetic CO(2) fixation proceeds in the mesophyll (M), the fixation process in C(4) plants is distributed between two cell types, the M cell and the bundle sheath (BS) cell. Here, we develop a C(4) genome-scale model (C4GEM) for the investigation of flux distribution in M and BS cells during C(4) photosynthesis. C4GEM, to our knowledge, is the first large-scale metabolic model that encapsulates metabolic interactions between two different cell types. C4GEM is based on the Arabidopsis (Arabidopsis thaliana) model (AraGEM) but has been extended by adding reactions and transporters responsible to represent three different C(4) subtypes (NADP-ME [for malic enzyme], NAD-ME, and phosphoenolpyruvate carboxykinase). C4GEM has been validated for its ability to synthesize 47 biomass components and consists of 1,588 unique reactions, 1,755 metabolites, 83 interorganelle transporters, and 29 external transporters (including transport through plasmodesmata). Reactions in the common C(4) model have been associated with well-annotated C(4) species (NADP-ME subtypes): 3,557 genes in sorghum, 11,623 genes in maize, and 3,881 genes in sugarcane. The number of essential reactions not assigned to genes is 131, 135, and 156 in sorghum, maize, and sugarcane, respectively. Flux balance analysis was used to assess the metabolic activity in M and BS cells during C(4) photosynthesis. Our simulations were consistent with chloroplast proteomic studies, and C4GEM predicted the classical C(4) photosynthesis pathway and its major effect in organelle function in M and BS. The model also highlights differences in metabolic activities around photosystem I and photosystem II for three different C(4) subtypes. Effects of CO(2) leakage were also explored. C4GEM is a viable framework for in silico analysis of cell cooperation between M and BS cells during photosynthesis and can be used to explore C(4) plant metabolism.

C4 photosynthesis: principles of CO2 concentration and prospects for its introduction into C3 plants

C(4) photosynthesis has a number of distinct properties that enable the capture of CO(2) and its concentration in the vicinity of Rubisco, so as to reduce the oxygenase activity of Rubisco, and hence the rate of photorespiration. The aim of this review is to discuss the properties of this CO(2)-concentrating mechanism, and thus to indicate the minimum requirements of any genetically-engineered system. In particular, the Kranz leaf anatomy of C(4) photosynthesis and the division of the C(4)-cycle between two cell types involves intercellular co-operation that requires modifications in regulation and transport to make C(4) photosynthesis work. Some examples of these modifications are discussed. Comparisons are made with the C(4)-type photosynthesis found in single-celled C(4)-type CO(2)-concentrating mechanisms, such as that found in the aquatic plant, Hydrilla verticillata and the single-celled C(4) system found in the terrestrial chenopod Borszczowia aralocaspica. The outcome of recent attempts to engineer C(4) enzymes into C(3) plants is discussed.

Photosynthetic Mechanisms of Weeds in Taiwan

One hundred and one species (in 36 families) of weeds on cultivated land in Taiwan were investigated for the occurrence of Kranz leaf anatomy and activities of key enzymes of C4 photosynthesis to determine their photosynthetic mechanisms. Based on the anatomical and biochemical analyses, 75 species were found to possess the C3 and 26 species the C4 pathway of photosynthetic CO2 fixation. Among the 26 C4 species, 15 species are in Gramineae, 6 in Cyperaceae, 2 each in Euphorbiaceae and Amaranthaceae, and 1 in Portulacaceae. Two C4 species in the Gramineae, namely Digitaria radicosa (Presl) Miq. and Sporobolus fertilis (Steud.) Clayton, were recorded as C4 plants for the first time. The biochemical subdivisions of these C4 weeds were also determined. As in the natural C4 populations, the NADP-malic enzyme subtype of C4 photosynthesis dominates the list of C4 weeds on this island (62%), while the PEP carboxykinase subtype is relatively rare (12%). NAD-malic enzyme subtype has an intermediate representation (26%). The high proportion of weeds in Taiwan being C3 plants is noteworthy, and it may be accounted for by the high precipitation in this subtropical island.

A Fossil Grass (Gramineae: Chloridoideae) from the Miocene with Kranz Anatomy

A fossil leaf fragment collected from the Ogallala Formation of northwestern Kansas exhibits features found in taxa of the modern grass subfamily Chloridoideae. These include bullet-shaped, bicellular microhairs, dumbbell-shaped silica bodies, cross-shaped suberin cells, papillae, stomata with low dome- to triangular-shaped subsidiary cells, and Kranz leaf anatomy. The leaf fragment extends the fossil record of plants that show both anatomical and external micromorphological features indicating C(4) photo-synthesis back to the Miocene. On the basis of associated mammals, the leaf fragment is assigned a Hemphillian age (7 to 5 million years ago).

A New Grass Genus from Australia

Whilst working on a revision of the Australian species of Stipa I noticed that several undetermined specimens were only superficially similar to species of Stipa and decided that they would best be treated as a new species in a new genus. This new species is a hummock-forming perennial with Kranz leaf anatomy similar to the 'hard' type (Jacobs 1971; Carolin, Jacobs & Vesk 1973) found in both Triodia and Plectrachne; the awn is almost circular in transsection, consisting of an outer complete layer of unevenly thickened fibres (thickest on the outer tangential wall) with an inner tissue of parenchymatous cells containing a central vascular bundle, quite unlike the awn anatomy of Stipa with its flattened awn (in trans-section) and two lateral cylinders of chlorenchyma (Duval-Jouve 1871). Although its relationships are clearly with Triodia and Plectrachne this new taxon differs from both in the single bisexual floret per spikelet and in the long, single, terminal awn on the lemma.

The Kranz syndrome in the Eragrostideae (Chloridoideae, Poaceae) as indicated by carbon isotopic ratios*

13C/12C ratios are generally regarded as being very reliable indicators of C3 or C4 photosynthesis. These relative carbon isotope ratios are expressed as a negative δ 3C and fall into two distinct groups: Kranz (or C4) plants with δ between -9°/00 no and -18°/00 and non-Kranz (C3) plants with δ between -22°/00 and -280/00 no. In this paper, 29 taxa, representing 12 genera, of the tribe Eragrostideae were examined by mass spectrometry for their δ 13C in dried leaf tissue. All these taxa proved to be C4, plants with δ13C values ranging between -13,6°/oo and -10.9°/oo. These findings confirmed published leaf anatomical observations which showed that all the studied taxa had characteristic Kranz leaf anatomy.

Photosynthetic Characteristics of Portulaca grandiflora, a Succulent C4 Dicot

The succulent, cylindrical leaves of the C(4) dicot Portulaca grandiflora possess three distinct green cell types: bundle sheath cells (BSC) in radial arrangement around the vascular bundles; mesophyll cells (MC) in an outer layer adjacent to the BSC; and water storage cells (WSC) in the leaf center. Unlike typical Kranz leaf anatomy, the MC do not surround the bundle sheath tissue but occur only in the area between the bundle sheath and the epidermis. Intercellular localization of photosynthetic enzymes was characterized using protoplasts isolated enzymatically from all three green cell types.Like other C(4) plants, P. grandiflora has ribulose 1,5-bisphosphate carboxylase and the decarboxylating enzyme, NADP(+)-malic enzyme, in the BSC. Unlike other C(4) plants, however, phosphoenolpyruvate carboxylase, pyruvate, Pi dikinase, and NADP(+)-malate dehydrogenase of the C(4) pathway were present in all three green cell types, indicating that all are capable of fixing CO(2) via phosphoenolpyruvate carboxylase and regenerating phosphoenolpyruvate. Other enzymes were about equally distributed between MC and BSC similar to other C(4) plants. The enzyme profile of the WSC was similar to that of the MC but with reduced activity in most enzymes, except mitochondrion-associated enzymes.Intracellular localization of enzymes was studied in organelles partitioned by differential centrifugation using mechanically ruptured mesophyll and bundle sheath protoplasts. Phosphoenolpyruvate carboxylase was a cytosolic enzyme in both cells; whereas, ribulose 1,5-bisphosphate carboxylase and NADP(+)-malic enzyme were exclusively compartmentalized in the bundle sheath chloroplasts. NADP(+)-malate dehydrogenase, pyruvate, Pi dikinase, aspartate aminotransferase, 3-phosphoglycerate kinase, and NADP(+)-triose-P dehydrogenase were predominantly localized in the chloroplasts while alanine aminotransferase and NAD(+)-malate dehydrogenase were mainly present in the cytosol of both cell types. Based on enzyme localization, a scheme of C(4) photosynthesis in P. grandiflora is proposed.Well-watered plants of P. grandiflora exhibit a diurnal fluctuation of total titratable acidity, with an amplitude of 61 and 54 microequivalent per gram fresh weight for the leaves and stems, respectively. These changes were in parallel with changes in malic acid concentration in these tissues. Under severe drought conditions, diurnal changes in both titratable acidity and malic acid concentration in both leaves and stems were much reduced. However, another C(4) dicot Amaranthus graecizans (nonsucculent) did not show any diurnal acid fluctuation under the same conditions. These results confirm the suggestion made by Koch and Kennedy (Plant Physiol. 65: 193-197, 1980) that succulent C(4) dicots can exhibit an acid metabolism similar to Crassulacean acid metabolism plants in certain environments.

C4 photosynthesis in Cyperus longus L., a species occurring in temperate climates

Abstract. Cyperus longus L., which has a widespread but disjunct distribution throughout Europe and extends northwards into Britain, was found to be a C4 species based upon its Kranz leaf anatomy, low CO2 compensation point and the labelling of malate as an early product of 14CO2 fixation. The photosynthetic characteristics of C. longus are similar to many other C4 species with a high maximum rate of photosynthesis (&gt; 1.5 mg CO2 m −2 s −1) and a relatively high temperature optimum (30–35°C), but unlike many C4 species the rate of photosynthesis does not decline rapidly below the optimum temperature and a substantial rate (0.6 mgCO2 m−2s−1)occursat 15°C. Leaf extension is very slow at 15°C and shows a curvilinear response to temperatures between 15 and 25°C. Leaves extend at a rate of almost 4 cm d−1 at 25°C.

C4 photosynthetic carbon metabolism in the leaves of aromatic tropical grasses ? I. Leaf anatomy, CO2 compensation point and CO2 assimilation

A few species of Cymbopogon and Vetiveria are potentially important tropical grasses producing essential oils. In the present study, we report on the leaf anatomy and photosynthetic carbon assimilation in five species of Cymbopogon and Vetiveria zizanioides. Kranz-type leaf anatomy with a centrifugal distribution of chloroplasts and exclusive localization of starch in the bundle sheath cells were common among the test plants. Besides the Kranz leaf anatomy, these grasses displayed other typical C4 characteristics including a low (0-5 µl/l) CO2 compensation point, lack of light saturation of CO2 uptake at high photon flux densities, high temperature (35°C) optimum of net photosynthesis, high rates of net photosynthesis (55-67 mg CO2 dm(-2) leaf area h(-1)), little or no response of net photosynthesis to atmospheric levels of O2 and high leaf (13)C/(12)C ratios. The biochemical studies with (14)CO2 indicated that the leaves of the above plant species synthesize predominantly malate during short term (5 s) photosynthesis. In pulse-chase experiments it was shown that the synthesis of 3-phosphoglycerate proceeds at the expense of malate, the major first formed product of photosynthesis in these plant species.

The occurrence of C4 species in the genusRhynchospora and its significance in kranz anatomy of the cyperaceae

Rhynchospora rubra was found to have a low CO2 compensation point, high δ13C value, Kranz leaf anatomy, starch present in the bundle sheath cells and narrow interveinal distance. These observations suggest thatR. rubra is a C4 plant. A further anatomical survey revealed seven otherRhynchospora species presumably having the C4 photosynthetic pathway. In the family Cypraceae C4 plants therefore occur in the tribe Rhynchosporeae as well as in the Scirpeae and Cypereae. The C4 species ofRhynchospora have a normal Kranz type of leaf anatomy, although the C4 species ofCyperus andFimbristylis presently known have an abnormal one in which the mestome sheath without chloroplasts is interposed between the Kranz tissue and the rest of the chlorenchyma. Thus inRhynchospora the Kranz tissue is in direct contact with the rest of the chlorenchyma, and it is suggested that the Kranz tissue may be homologous with the mestome sheath.

Photosynthetic carbon metabolism in Panicum milioides, a C 3-C 4 intermediate species: Evidence for a limited C 4 dicarboxylic acid pathway of photosynthesis

Panicum milioides, a naturally occurring species with C 4-like Kranz leaf anatomy, is intermediate between C 3 and C 4 plants with respect to photorespiration and the associated oxygen inhibition of photosynthesis. This paper presents direct evidence for a limited degree of C 4 photosynthesis in this C 3-C 4 intermediate species based on: 1. (a) the appearance of 24% of the total 14C fixed following 4 s photosynthesis in 14CO 2-air by excised leaves in malate and aspartate and the complete transfer of label from the C 4 acids to Calvin cycle intermediates within a 15 s chase in 12CO 2-air; 2. (b) pyruvate- or alanine-enhanced light-dependent CO 2 fixation and pyruvate stimulation of oxaloacetate- or 3-phosphoglycerate-dependent O 2 evolution by illuminated mesophyll protoplasts, but not bundle sheath strands; and 3. (c) NAD-malic enzyme-dependent decarboxylation of C 4 acids at the C-4 carboxyl position, C 4 acid-dependent O 2 evolution, and 14CO 2 donation from [4- 14C]C 4 acids to Calvin cycle intermediates during photosynthesis by bundle sheath strands, but not mesophyll protoplasts. However, P. milioides differs from C 4 plants in that the activity of the C 4 cycle enzymes is only 15 to 30% of a C 4 Panicum species and the Calvin cycle and phospho enolpyruvate carboxylase are present in both cell types. From these and related studies (Rathnam, C.K.M. and Chollet, R. (1979) Arch. Biochem. Biophys. 193, 346–354; (1978) Biochem. Biophys. Res. Commun. 85, 801–808) we conclude that reduced photorespiration in P. milioides is due to a limited degree of NAD-malic enzyme-type C 4 photosynthesis permitting an increase in pCO 2 at the site of bundle sheath, but not mesophyll, ribulosebisphosphate carboxylase-oxygenase.

Classification of C3 and C4 Turfgrass Species Based on CO2 Compensation Concentration and Leaf Anatomy1

Abstract Leaf anatomy and CO2 compensation concentration (Γ) were used to determine the carbon fixation pathway for 10 cool season and 5 warm season turfgrass species. Turfgrasses of the subfamily Festucoideae were representative of C3 plants. Turfgrass species of the subfamily Panicoideae and Eragrostoidea were representative of C4 plants. Turfgrasses classified traditionally as cool season or warm season species correlated with C3 and C4 plant types, respectively. Both techniques of C3 and C4 classification proved equally reliable in this study, however, the utilization of Kranz leaf anatomy required less preparation.

Simultaneous occurrence of C3 and C4 photosyntheses in relation to leaf position in Mollugo nudicaulis

SINCE the discovery of C4 photosynthesis1,2 higher plants have been categorised into C3 plants, which form 3-phosphoglycerate (PGA) as the first labelled intermediate, and C4 plants, which form 4-carbon acids as the predominant early photosynthetic products, C4 plants can also be distinguished by features such as Kranz leaf anatomy, low photorespiration, high photosynthetic efficiency and reduced 13C discrimination3. Although 943 C4 plants are known to be distributed among 18 families, only 18 genera from 10 families include both C3 and C4 plants4. Kennedy and Laetsch5 described Mollugo verticillata as intermediate for C3 and C4 photosynthesis. But Brown and Brown6 felt that it was a typical C3 plant. Recently three Panicum species (P. milioides, P. hians and P. laxum) have been found to have photosynthetic characteristics intermediate between C3 and C4 plants6–8. We now report that a single plant of Mollugo nudicaulis can have some leaves with C3 characteristics and others with C4 characteristics according to their position on the stem.

&lt;italic&gt;Panicum milioides&lt;/italic&gt;, a Gramineae plant having Kranz leaf anatomy without C&lt;sub&gt;4&lt;/sub&gt;-photosynthesis

Light and electron microscopic observations of the leaf tissue of Panicum milioides showed that the bundle sheath cells contained a substantial number of chloroplasts and other organelles. The radial arrangement of chlorenchymatous bundle sheath cells, designated as Kranz leaf anatomy, has been considered to be specific to C4 plants. However, photosynthetic 14CO2 fixation and 14CO2 pulse-and-chase experiments revealed that the reductive pentosephosphate pathway was the main route operating in leaves of P. milioides. The interveinal distance of the leaves was intermediate between C3and C4Gramineae species. These results indicate that P. milioides is a natural plant species having chracteristics intermediate between C3 and C4 types.