Angiosperm Leaf Research Articles

Purification of Chloroplast Envelope, Thylakoids, and Stroma from Angiosperm Leaves.

Plant cell chloroplasts are bounded by a two-membrane envelope. Their photosynthetic function is based on the development of an operational large internal membrane network, called the thylakoids, and on enzymatic processes present in the chloroplast matrix, called the stroma. Thylakoid membranes are distinct from the chloroplast envelope, and their biogenesis is dependent on biosynthetic and transport activities specific of the chloroplast envelope. Starting with the isolation of intact chloroplasts, the method presents the separation by differential centrifugation of the three compartments. A protocol is detailed for leaves of spinach, Arabidopsis or pea.

A new fossil angiosperm from the Early Cretaceous (early Aptian) of the Zhongkouzi Basin in the Beishan area, Northwest China

ABSTRACT A new angiosperm is reported based on a leaf specimen from the Early Cretaceous Chijinpu Formation in Beishan area, Northwest China. The associated plants include abundant gymnosperms and ferns. The new angiosperm leaf, discovered for the first time in this region, has a cordate base and peltate excentric lamina attachment. Cluster analysis and morphological comparisons with other angiosperm leaves show that this specimen is more similar to peltate fossil leaves. However, the exact taxonomic position of this fossil leaf is uncertain due to limited characters, so that we established a new genus and species, Gansupeltata beishanensis gen. et sp. nov. The new finding adds to the diversity of early angiosperms, and further demonstrates that angiosperms have already evolved during the Early Cretaceous in the Beishan area, Northwest China.

Flora, vegetation and climate assessment of the Early/Middle Miocene Parschlug flora indicates a distinctly seasonal climate

The late Early/early Middle Miocene flora from Parschlug (Styria, Austria) is famous for its numerous specimens and high diversity. Some taxa previously described are revised here and 42 new angiosperm leaf morphotypes/taxa are described. The Climate Leaf Analysis Multivariate Program (CLAMP) is applied to assess the palaeoclimate. An update of the tool to assess the most suitable modern climate CLAMP calibration dataset is introduced. The Integrated Plant Record (IPR) vegetation analysis, assessing the most likely major vegetation type represented by a fossil flora, and similarity approaches Drudges 1 and 2, indicating the most similar modern vegetation proxies, had been previously applied to data from Parschlug. Both are again applied here on the enlarged floristic spectrum. The results indicate “sclerophyllous subhumid forest” as the most likely major zonal vegetation type for Parschlug and European vegetation, namely “Thermophilous mixed deciduous broadleaved forests”, distributed today in southern and southeastern Europe, as the most similar modern vegetation. The climate for Parschlug, inferred from CLAMP and the climate in the region of the modern vegetation proxies, indicates distinct seasonality in precipitation and temperature.

Galling: the prevalent form of insect folivory in the latest Neogene monsoon-influenced tropical forests of the Chotanagpur Plateau, eastern India

Indian Cenozoic deposits contain well-preserved diverse angiosperm leaf assemblages, but galling, a common form of angiosperm leaf damage in modern tropical forests, has not been well-documented. Here we report insect herbivory on diverse angiosperm fossil leaf specimens from Pliocene (Rajdanda Formation) sediments of the Chotanagpur Plateau, eastern India, revealing that galling was the most common form of folivory in the latest Neogene monsoon-adapted tropical forests of eastern India. Diverse well-preserved galls are described on the basis of their size, shape and position on the host angiosperm leaf remains. Nine gall damage types (DT 32, DT 33, DT 34, DT 80, DT 83, DT 85, DT 110, DT 120, and DT 144) are identified. They are compared with extant galls and the probable gall inducers making morphologically similar galls on related host tropical plant species of Ficus, Mangifera, Albizia, Galactia, Ziziphus, Hylodesmum, Adina, and Psidium. The gall producers belong to the insect orders Orthoptera, Hemiptera, Hymenoptera, Coleoptera, Lepidoptera, and Diptera (Cecidomyiidae). Although the detailed morphology of the phytophagous insects associated with the recovered fossil leaves is unknown, our findings indicate that many modern plant-insect relationships were likely established by the Pliocene. The reconstructed warm, humid Pliocene climate with a weak monsoon seasonality was conducive to extensive galling activity during this time.

First fossil evidence of leaf‐feeding caterpillars from India and their feeding strategies

Evidence of predatory marks on fossil leaf remains provides a unique window into ecological and evolutionary associations of the past, but finding both damage and the phytophagous insects causing that damage pattern in the same fossil specimen is a very rare phenomenon. Normally, caterpillars have little fossilization potential because of their delicate structure, but here, we present the first fossil evidence of leaf-feeding caterpillars, along with their characteristic feeding patterns, on the surface of diverse angiosperm leaf remains recovered from the latest Neogene (Pliocene, Rajdanda Formation) sediments of Chotanagpur Plateau, eastern India. This provides a rare direct insight into past plant-insect interaction, allowing us to identify, with confidence, the relationship between leaf damage and the perpetrator. The present finding also reveals that caterpillar-plant relationships and their feeding strategies seen today also existed during the Pliocene.

Geographic variation of leaf form among indigenous woody angiosperms in New Zealand

ABSTRACT Correlations of non-monocot woody angiosperm leaf traits to macroclimate are often used to reconstruct terrestrial paleoclimate under the assumption that macroclimate correlates with leaf phenotype are globally uniform, regardless of evolutionary history. Here, we evaluate if global trends in leaf trait variation with macroclimate are observed in the predominantly evergreen indigenous flora of New Zealand. A dataset of 557 indigenous woody dicot species and over 100,000 occurrences was employed to investigate community-level relationships of four leaf characters (leaf pubescence, margin teeth, area and length-to-width ratio) with geographic variation in temperature, precipitation, water deficit and solar radiation. Leaf area and the frequency of toothed leaves decline at higher latitudes in New Zealand. Variation in leaf pubescence and leaf teeth is associated primarily with measures of water availability, such as annual rainfall and annual water deficit; whereas leaf size is associated primarily with temperature. Variation in leaf length-to-width ratio was weakly correlated to climate parameters. The New Zealand relationship of leaf area with temperature aligns with global patterns, highlighting the importance of small leaves in limiting night-time chilling. The global negative correlation of leaf teeth with temperature is apparent in New Zealand trees and vines, but not in shrubs or all woody dicots combined. However, the primary correlate of leaf teeth in New Zealand is water availability, showing that the response of this trait to macroclimate is not globally uniform. The high occurrence of pubescent leaves in low rainfall and drought-prone environments in New Zealand suggests that the trait is associated with water retention in drier climates.

Taxon- and senescence-specific fluorescence of colored leaves from the Pliocene Willershausen Lagerst\xe4tte, Germany

UV-light-induced fluorescence is widely used in the study of coal macerals and palynological samples, but to date has not been described in great detail for plant macrofossils. Here, we report the characteristics of bright UV-light-induced fluorescence of various fossil angiosperm leaf taxa from the Upper Pliocene of Willershausen, Lower Saxony, Germany. The fluorescence is exceptional, since different fluorescence colors ranging from green to yellow to red can be observed and fluorescence properties are found to be related to genera. Using confocal laser scanning microscopy, fluorescence was studied in detail and emission spectra were obtained that allowed to differentiate broad groups of fluorophores. Fluorescence emissions attributed to chlorophyll degradation products demonstrate that fluorescence can be used as an indicator for exceptional chemical preservation of leaf fossils. Comparison with present-day senescing plants suggests that the fluorescence differences in the fossil leaves are mainly caused by taxon-specific degeneration of organic compounds during senescence. The occurrence of various leaf taxa with different fluorescence properties, preserved under identical conditions of fossilization, indicate that diagenesis was not crucial for the differences in leaf fluorescence.

On the Efficacy of Water Transport in Leaves. A Coupled Xylem-Phloem Model of Water and Solute Transport

In this paper, we present and use a coupled xylem/phloem mathematical model of passive water and solute transport through a reticulated vascular system of an angiosperm leaf. We evaluate the effect of leaf width-to-length proportion and orientation of second-order veins on the indexes of water transport into the leaves and sucrose transport from the leaves. We found that the most important factor affecting the steady-state pattern of hydraulic pressure distribution in the xylem and solute concentration in the phloem was leaf shape: narrower/longer leaves are less efficient in convecting xylem water and phloem solutes than wider/shorter leaves under all conditions studied. The degree of efficiency of transport is greatly influenced by the orientation of second-order veins relative to the main vein for all leaf proportions considered; the dependence is non-monotonic with efficiency maximized when the angle is approximately 45° to the main vein, although the angle of peak efficiency depends on other conditions. The sensitivity of transport efficiency to vein orientation increases with increasing vein conductivity. The vein angle at which efficiency is maximum tended to be smaller (relative to the main vein direction) in narrower leaves. The results may help to explain, or at least contribute to our understanding of, the evolution of parallel vein systems in monocot leaves.

In situ occurrence of a gall midge (Insecta, Diptera, Cecidomyiidae) on fossilized angiosperm leaf cuticle fragments from the Pliocene sediments of eastern India

Abstract In situ preservation of fossil insect damage in plant fossils is an excellent tool to study the coevolution of flora and fauna through geological time, but finding both damage and the insect causing that damage in the same specimen is a very rare phenomenon. Galling is a common form of angiosperm leaf damage, which can be regarded as a kind of extended phenotype of the causal insects, essentially the gall midges, but galls usually lack remains of the insects themselves. Here we report the in situ occurrence of a gall midge (Insecta, Diptera, Cecidomyiidae) as well as its pupal exuviae on the abaxial cuticular surface of fossilized leaf cuticle fragments of Fabaceae leaves (cf. Albizia) that also bear galls, recovered from the latest Neogene (Rajdanda Formation, Pliocene) sediments of the Chotonagpur Plateau, Jharkhand, northeastern India. This Pliocene gall midge features well-preserved legs, segmented antenna with distinct and enlarged scape, elongate curved setae, and longer than broad terminal plate of the ovipositor lamellae. The in situ presence of a gall midge on a host fabaceous leaf cuticle indicates the existence of a host-ectoparasite relationship in the ancient warm and humid tropical monsoon-influenced forests of eastern India during the Pliocene. This is the first authentic fossil record of an in situ phytophagous insect of Cecidomyiidae from India, as well as southeast Asia. Although the identification of the recovered phytophagous insect associated with the fossil leaf cuticle is only possible to family level, this find reveals that such plant-insect relationships existed in the Pliocene of eastern India.

Vein Distribution on the Deformation Behavior and Fracture Mechanisms of Typical Plant Leaves by Quasi In Situ Tensile Test under a Digital Microscope.

Angiosperm leaf venation is based on two major patterns, typically dicotyledonous branching and monocotyledonous parallel veins. The influence of these patterns on deformation and fracture properties is poorly understood. In this paper, three species of dicotyledons with netted venation and three species of monocots with parallel venation were selected, and the effect of vein distribution of leaves on their mechanical properties and deformation behavior was investigated. Whole images of leaves were captured using a digital camera, and their vein traits were measured using the image processing software Digimizer. A self-developed mechanical testing apparatus with high precision and low load was used to measure the tensile properties of leaves. The deformation behavior of the leaf was captured using a digital microscope during the tensile test. Results showed that the vein architecture of monocots and dicots is different, which had a remarkable effect on their mechanical properties, deformation behavior, and crack propagation behavior. The greater the diameter and the more the number of veins parallel to the tensile direction, the higher the tensile force, tensile strength, and elastic modulus of the leaves. The netted venation leaves evinced the elastic-plastic fracture type, and the hierarchy venation provided resistance to fracture propagation of cracks in the leaves by lengthening the crack path. The leaves with parallel venation behaved in a predominantly brittle manner or elastic fracture type, and the parallel venation inhibited the initiation of cracks in the leaves by increasing the load at complete fracture of the leaves. The investigation provides reference for a stiffened plate/shell structure and bionic anticrack design.

The Kanaka Creek fossil flora (Huntingdon Formation), British Columbia, Canada — paleoenvironment and evidence for Paleocene age using palynology and macroflora

Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighbouring Washington State, USA, are exposed in the Greater Vancouver area, British Columbia, Canada. Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian. Analyses of plant macro- and micro-fossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Physiognomy of 41 angiosperm leaf morphotypes from Kanaka Creek yields mean annual temperatures in the microthermal to lower mesothermal range (11.2 ± 4.3 to 14.6 ± 2.7 °C from leaf margin analysis; 14.8 ± 2.1 °C from Climate Leaf Analysis Multivariate Program), with mild winters (cold month mean temperature 3.9 ± 3.4 °C). Paleoclimate was cooler than the upper Paleocene and Eocene members of the Chuckanut Formation. Mean annual precipitation is estimated at ∼140 cm with large uncertainties. The Kanaka paleoflora is reconstructed as a mixed conifer–broadleaf forest, sharing common taxa with other western North American Paleocene floras and growing in a temperate moist climate. Kanaka Creek is a rare coastal Paleocene plant locality that provides new insights into coastal vegetation and climate prior to the Paleocene–Eocene Thermal Maximum.

Chloroplast nucleoids are highly dynamic in ploidy, number, and structure during angiosperm leaf development.

Chloroplast nucleoids are large, compact nucleoprotein structures containing multiple copies of the plastid genome. Studies on structural and quantitative changes of plastid DNA (ptDNA) during leaf development are scarce and have produced controversial data. We have systematically investigated nucleoid dynamics and ptDNA quantities in the mesophyll of Arabidopsis, tobacco, sugar beet, and maize from the early post-meristematic stage until necrosis. DNA of individual nucleoids was quantified by DAPI-based supersensitive epifluorescence microscopy. Nucleoids occurred in scattered, stacked, or ring-shaped arrangements and in recurring patterns during leaf development that was remarkably similar between the species studied. Nucleoids per organelle varied from a few in meristematic plastids to >30 in mature chloroplasts (corresponding to about 20-750 nucleoids per cell). Nucleoid ploidies ranged from haploid to >20-fold even within individual organelles, with average values between 2.6-fold and 6.7-fold and little changes during leaf development. DNA quantities per organelle increased gradually from about a dozen plastome copies in tiny plastids of apex cells to 70-130 copies in chloroplasts of about 7μm diameter in mature mesophyll tissue, and from about 80 plastome copies in meristematic cells to 2600-3300 copies in mature diploid mesophyll cells without conspicuous decline during leaf development. Pulsed-field electrophoresis, restriction of high-molecular-weight DNA from chloroplasts and gerontoplasts, and CsCl equilibrium centrifugation of single-stranded and double-stranded ptDNA revealed no noticeable fragmentation of the organelle DNA during leaf development, implying that plastid genomes in mesophyll tissues are remarkably stable until senescence.

Quantitative methods in like-for-like comparative analyses of Aphanorrhegma (Physcomitrella) patens phyllid development.

ABSTRACTIntroduction. Aphanorrhegma (Physcomitrella) patens (Hedw.) Lindb. is an attractive model system for comparative analyses of leaf development because it evolved leaves (phyllids) independently to flowering plants, yet its genome contains homologues of many gene families that regulate angiosperm leaf development. In addition, A. patens phyllids are primarily a single cell layer thick, making it simple to identify the cellular basis of defects that perturb shape. Identification of gene functions in shape determination depends on like-for-like comparison of mutant versus wild-type plants.Key results. Here we show that, if heteroblasty is not perturbed, such comparisons should use phyllid L13 or above in the heteroblastic series, and fully expanded phyllids above P7 in the developmental series. Using a quantitative approach, we show that heteroblastic size variation reflects differences in cell proliferation rather than cell size and shape. A comparison of control to pinA pinB mutant phyllid development verifies that PIN proteins promote cell proliferation and suppress expansion to determine phyllid shape.Conclusion. The results and approach that we have generated will be applicable to any study of A. patens phyllid development to reveal the cellular basis of phyllid size and shape variations.

A new foliicolous melioloid fungus from the Pliocene of eastern Himalaya

We report the in situ occurrence of a new species of Meliolinites (fossil Meliolaceae, Ascomycota), Meliolinites pliocenicus, on the lower epidermal surface of fossilized angiosperm leaf of Shorea siwalika (Dipterocarpaceae) recovered from the middle Siwalik stratum (Subansiri Formation: Pliocene) of Arunachal sub-Himalaya. This fungal morph is characterized by well-preserved unique mycelia consisting of superficial, dark brown, thick-walled, branching hyphae with appressoria as well as phialides and dispersed ellipsoidal, 3-septate, 4-celled, dark brown ascospores. The in situ evidence of the fungus on the fossil leaf cuticle indicates the prevalence of a warm, humid, tropical climate in Arunachal sub-Himalaya during the deposition and further suggests that a possible host-ectoparasite relationship existed in the ancient forest of this area during the Pliocene time.

A new fossil genus of angiosperm leaf from the Olmos Formation (upper Campanian), of northern Mexico

The Olmos Formation (upper Campanian) is located in the Sabinas Basin in northern Mexico. It represents a deltaic-fluvial system, and it is known by its abundance of fossil plants mainly represented by leaves and woods. In this contribution, we describe angiosperm fossil leaves, related to ?Violaceae. The new fossil genus has pinnate venation, with a major secondaries festooned semicraspedodromous, tertiary venation opposite percurrent, quaternary veins irregular reticulate, margin crenulated with tooth terminating in a glandular tissue, and fimbrial vein present. This mosaic of characteristics supports the creation of a new genus and species, Mascogophyllum elizondoa Centeno-González, Porras-Múzquiz et Estrada-Ruiz (?Violaceae). This record could be the oldest of the family; also, a new family is added to the very diverse fossil flora record that established during the Cretaceous in the northern of Mexico.

A mid-Cretaceous pycnidia, Palaeomycus epallelus gen. et sp. nov., in Myanmar amber

ABSTRACTFive separate epiphyllous pycnidia on the remains of an angiosperm leaf in mid-Cretaceous Myanmar amber are described as Palaeomycus epallelus gen. et sp. nov. The new taxon is characterized by dark, superficial, globose, uniloculate pycnidia with a multicellular wall of aggregated cells, a wide circular ostiole and conidiophores aligned in closely packed rows with one or more terminal branches bearing ovoid to ellipsoidal, hyaline, aseptate conidia. This fossil represents the oldest pycnidia found on an angiosperm leaf.

Frost and leaf-size gradients in forests: global patterns and experimental evidence.

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.

Angiosperm leaves and cuticles from the uppermost Cretaceous of Patagonia, biogeographic implications and atmospheric paleo-CO2 estimates

The study of plant material from localities of Late Cretaceous age from southern latitudes is fundamental to improve our understanding of global patterns of angiosperm evolution, diversity, paleoecology, and biogeography. Herein, angiosperm leaf fossils of the recently discovered Cañadón del Loro locality, from the Maastrichtian portion of the Lefipán Formation, Patagonia, Argentina are studied. Leaf architecture was used to differentiate morphotypes, to describe them, and to make comparisons with other southern latitudes floras of similar age. Six angiosperm leaf morphotypes were described from 132 collected specimens; one of them, with exceptional preservation, was named Lefipania padillae gen. et sp. nov. and its cuticle anatomy and insect damage were also described. The Cañadón del Loro fossils represent a local assemblage of low diversity deposited in an upper delta plain. Biogeographically, L. padillae was widespread throughout the southern hemisphere during the Late Cretaceous, possibly favored by a warm climate and the geographical proximity of these southern landmasses. The morphotype with well-preserved cuticles clearly shows four insect damage types attributed to feeding. This morphotype was also used for estimating paleo-atmospheric CO2 concentration (pCO2), using a stomatal-proxy gas exchange model, which resulted in approximately 464 ppm. The estimated pCO2 is in agreement with previous estimations for this time interval and supports the hypothesis of a decrease of pCO2 towards end of the Cretaceous.

Structural and defensive roles of angiosperm leaf venation network reticulation across an Andes–Amazon elevation gradient

Abstract The network of minor veins of angiosperm leaves may include loops (reticulation). Variation in network architecture has been hypothesized to have hydraulic and also structural and defensive functions. We measured venation network trait space in eight dimensions for 136 biomass‐dominant angiosperm tree species along a 3,300 m elevation gradient in southeastern Peru. We then examined the relative importance of multiple ecological and evolutionary predictors of reticulation. Variation in minor venation network reticulation was constrained to three axes. These axes described reconnecting vs. branching veins, elongated vs. compact areoles compact vs. elongated and low vs. high‐density veins. Variation in the first two axes was predicted by traits related to mechanical strength and secondary compounds, and in the third axis by site temperature. Synthesis. Defensive and structural factors primarily explain variation in multiple axes of reticulation, with a smaller role for climate‐linked factors. These results suggest that venation network reticulation may be determined more by species interactions than by hydraulic functions.

Impressões foliares pleistocenas de Malvaceae na área de abrangência do Aproveitamento Hidroelétrico Jirau, Rondônia, Brasil

Este trabalho tem como objetivo descrever a morfologia foliar e realizar o reconhecimento taxonô- mico de dez impressões foliares de angiospermas coletadas em afloramento da Formação Rio Madeira na área de abrangência do Aproveitamento Hidrelétrico (AHE) Jirau, resgatadas pela equipe do Programa de Investiga- ção, Salvamento e Monitoramento Paleontológico. Devido à preservação e com base na descrição morfológica, os espécimes foram identificados até o nível de gênero. Todos os espécimes mostram caracteres que indicam sua relação com a família Malvaceae, nove deles com o gênero Luehea e um exemplar ao gênero Theobroma. Duas amostras foram retiradas da camada inferior àquela que concentra os fósseis, com o objetivo de realizar datação através do método “Accelerator Mass Spectrometry” (AMS C14). A datação apontou idades entre 15.910 e 14.850 anos calibrados AP. Os dois gêneros registrados são comuns na cobertura florestal atual na região do AHE Jirau, e a sua presença é também confirmada pelos dados palinológicos obtidos para a parte superior da Formação Rio Madeira.