Well-preserved Plant Research Articles

Auxin analysis using laser microdissected plant tissues sections

BackgroundQuantitative measurement of actual auxin levels in plant tissue is complimentary to molecular methods measuring the expression of auxin related genes. Current analytical methods to quantify auxin have pushed the limit of detection to where auxin can be routinely quantified at the pictogram (pg) level, reducing the amount of tissue needed to perform these kinds of studies to amounts never imagined a few years ago. In parallel, the development of technologies like laser microdissection microscopy (LMD) has allowed specific cells to be harvested from discrete tissues without including adjacent cells. This method has gained popularity in recent years, especially for enabling a higher degree of spatial resolution in transcriptome profiling. As with other quantitative measurements, including hormone quantifications, sampling using traditional LMD is still challenging because sample preparation clearly compromises the preservation of analytes. Thus, we have developed and validated a sample preparation protocol combining cryosectioning, freeze-drying, and capturing with a laser microdissection microscope to provide high-quality and well-preserved plant materials suitable for ultrasensitive, spatially-resolved auxin quantification.ResultsWe developed a new method to provide discrete plant tissues for indole-3-acetic acid (IAA) quantification while preserving the plant tissue in the best possible condition to prevent auxin degradation. The method combines the use of cryosectioning, freeze-drying and LMD. The protocol may also be used for other applications that require small molecule analysis with high tissue-specificity where degradation of biological compounds may be an issue. It was possible to collect the equivalent to 15 mg of very specific tissue in approximately 4 h using LMD.ConclusionsWe have shown, by proof of concept, that freeze dried cryosections of plant tissue were suitable for LMD harvest and quantification of the phytohormone auxin using GC-MS/MS. We expect that the ability to resolve auxin levels with both spatial- and temporal resolution with high accuracy will enable experiments on complex processes, which will increase our knowledge of the many roles of auxins (and, in time, other phytohormones) in plant development.

A new protolepidodendrid lycopsid from the Middle Devonian of Hunan, South China and its palaeogeographic implications

Well-preserved plant compression from the Middle Devonian Tiaomachian Formation of Hunan, the central area of South China allow establishing a new species of protolepidodendrid, morphologically Colpodexylon-like lycopsid, Tiaomaphyton fui gen. et sp. nov. The new plant is small-sized and consists of three-tipped leaves with a tiny heel and longitudinal dehiscent sporangia. Tiaomaphyton is the first unequivocal protolepidodendrid lycopsid from the Middle Devonian of central Hunan, which palaeogeographically belongs to the Cathaysia Block, one of the two sub-regions of the whole South China Plate. The study gives a better understanding of the Middle Devonian flora of Cathaysia block and has palaeogeographic implications to the South China Plate. A floristic distinction between the Cathaysia and Yangtze blocks is suggested and it is probably caused by the special palaeogeographic pattern of the South China Plate.

Paleoethnobotany of the Early Initial Period of Gramalote in Northern Peru

The Gramalote site is an early Initial Period (1500–1200 B.C.E.) fishing village located in the Moche valley in northern Peru. Previous research assessed the social dynamics and economic interactions within that fishing settlement. The well-preserved animal and plant record facilitates the archeological study of diet and subsistence strategies through time. The examinations of faunal remains of seabirds, sea mammals, and mollusk shells support the expected marine-oriented subsistence strategy. However, the site also contains a long record of botanical remains suggesting that people had access to plant resources. For this reason, a paleoethnobotanical study was conducted with the focus on reconstructing the pollen record of Gramalote. Previously identified botanical remains were also considered. The analysis of diverse botanical proxies helped to study the relationships between humans and plants in this region of northern Peru during the second millennium B.C.E. Grasses; reeds; food, woody, and wild plants were identified suggesting an environment that allowed small-scale agriculture and a trading network during the Initial Period of Gramalote.

Characterization of labile organic matter in Pleistocene permafrost (NE Siberia), using Thermally assisted Hydrolysis and Methylation (THM-GC-MS)

Pleistocene yedoma sediments store large amounts of soil organic matter (SOM) and are vulnerable to permafrost degradation. Here we contribute to our understanding of yedoma SOM dynamics and potential response to thaw, by molecular characterization of samples from a 5.7 m yedoma exposure, as well as upper permafrost samples that were previously incubated, using Thermally assisted Hydrolysis and Methylation (THM-GC-MS). In general, the SOM is derived from aliphatic material (including cutin and suberin), phenols (lignin, sphagnum acid), polysaccharides and N-containing components (largely microbial SOM). Soil organic carbon (SOC) content and molecular SOM composition follow a sawtooth pattern where local maxima in SOC coincide with lignin and aliphatic material that experienced only slight degradation, and minima with degraded plant-derived SOM and microbial tissue, representing a stratified cryopedolith. The SOC-depleted top 0.9 m (active layer and transition zone) is enriched in microbial SOM probably due to recent thawing. Comparison with CO2 respiration rates indicates that SOM of microbial origin (low C/N) is more labile than aliphatic SOM from well-preserved plant tissue (high C/N). However, we argue that the more stable aliphatic SOM in SOC-rich layers might also be vulnerable to decay, which could, due to its abundance in SOC-rich layers, dominate overall Yedoma C losses due to thermal erosion.

Peltaspermalean seed ferns with preserved cuticle from the Upper Triassic Karamay Formation in the Junggar Basin, northwestern China

Foliage of a new peltaspermalean seed fern is described on the basis of a large collection of well-preserved plant adpressions with cuticle from the Upper Triassic Karamay Formation in Xinjiang Province, NW China. Pinnae are lanceolate with undulate-dentate margins and with fascicular lateral veins in lobes. Tertiary veins are simple as are interfascicular veins that occur between fascicular lateral veins. Cuticles are thick, amphistomatic, with abaxial and adaxial cuticles being similar to each other and having clear costal and intercostal areas. Stomata are sunken and randomly distributed on both the abaxial and the adaxial cuticle. The stomatal complex is monocyclic and comprises 4–7 subsidiary cells. Papillae are present on ordinary cells and on subsidiary cells surround the stomatal aperture. The adaxial leaf surface has a stomatal index of 3.27 and an average stomatal density of 15permm2, whereas the abaxial surface has a stomatal index of 5.25 and an average stomatal density of 30permm2. This is the first report of the cuticular structure of Scytophyllum from the Junggar Basin, which now enables detailed comparison with other species of the genus from Eurasia. Analysis of the sedimentary succession containing Scytophyllum suggests a humid or seasonally dry environment, but the thick cuticles with sunken stomata and abundant papillae indicate that the plant was adapted to living in water-stressed conditions.

Drilling wood for fire: discoveries and studies of the fire-making tools in the Yanghai cemetery of ancient Turpan, China

A fire drilling tool was a vital piece of equipment in ancient times for creating fire, and an understanding of the shape of ancient fire drills, the different ways of wood drilling and the strategy of wood selection are of great importance for studying past societies. Due to poor environmental conditions, equipment associated with the making of fire is rarely preserved at archaeological sites in China, and the anatomical characters of these wooden tools have never been investigated. However, the Turpan District in Xinjiang, China is characterized by year-round drought conditions, which provide us with well-preserved plant remains for studying the types of plants used for making fire drills. In the present work, 12 fire drilling tools from ten tombs of the Yanghai cemetery (c.1000 bc–ad 100) were studied. These fire drilling tools were identified as having been made from the wood of Picea sp., Salix sp., Populus sp., Clematis sp. or Aristolochia sp., with the former four taxa native to the local area. The anatomical characteristics of the wood suggest that all of these selected wood types were suitable for use in fire drills. In addition, among the different kinds of fire drilling methods, we found that hand drilling was the main method used by the ancient Yanghai inhabitants and that fire drills played an important part in their pastoral life.

Preliminary analysis of detrital zircon U–Pb ages from the fossil-rich Tabbowa beds, Sri Lanka

The Jurassic Tabbowa beds of northwestern Sri Lanka contain various plant fossils, including conifer, cycad, and fern. Well-preserved plant fossils have been discovered in mudstone and brownish siltstone horizons of the sandstone units since the early 20th century. Recent investigations for example have identified Otozamites latiphyllus and Otozamites tabbowensis fossils within these sediments. These species belong to an extinct seed plant of the Bennettitales order, which occurred throughout Gondwana during the Jurassic. Additionally, diverse assemblages of insect trace fossils have been found from the leaves of plant fossils. These insect trace fossils and plant fossils provide a unique window into Mesozoic plant–insect relationships and Jurassic terrestrial ecosystems. However, a majority of the Tabbowa fossils have not been systematically investigated or described in international journals. The Tabbowa beds also lack definitive stratigraphic correlation and sedimentary interpretation. This study describes the geologic context of the Tabbowa beds, summarizes previous studies of the Tabbowa Basin, and interprets chronostratigraphic constraints using detrital zircon U–Pb geochronology. Furthermore, our work demonstrates some of the limitations of detrital zircon geochronology and suggests the need for alternative methods in order to establish chronostratigraphic constraints on the Tabbowa beds.

Caddo Ceramic Vessels from the Eli Moores Site (41BW2), Bowie County, Texas

The Eli Moores site (41BW2) is an important ancestral Caddo mound center and habitation site on the Red River in the East Texas Pineywoods, likely part of the Nasoni Caddo village visited by the Teran de los Rios entrada in 1691. The Eli Moores site is situated on a natural levee of the Red River, currently about 2.5 km north of the site. The site, occupied from the 17th to the early 18th century, may have been the residence of the Caddi of the Nasoni Caddo when it was visited by the French and Spanish, and the Xinesi lived in a temple on the mound at the nearby Hatchel site (41BW3). The site was investigated by the University of Texas in 1932, and in one of the mounds and in associated midden deposits, the remains of Caddo structures, midden deposits, features, eight burials (with nine individuals), and a large ceramic and lithic assemblage were recovered, along with well-preserved plant and faunal remains.

On the Interpretation of Fossil Nuclei

Although organelle preservation in plant fossils is not novel and well-preserved plant mesofossils have contributed greatly to the understanding of plant evolution, subcellular structures are still a rarity in plant mesofossils. Although it is not easy to explore subcellular structures in plant fossils, related attempts are frequently seen. Among them, some false interpretation requires further inspection. To shed more light on this issue, here I studied Cretaceous charcoalified mesofossils from USA, using LM (light microscopy), SEM (scanning electron microscopy) and TEM (transmission electron microscopy) technologies. My conclusion shows that not all publications reflect the truthful existence of nuclei in plant fossils, and this study may provide a reference for the future research.

Study of the Histology of Leafy Axes and Male Cones of Glenrosa carentonensis sp. nov. (Cenomanian Flints of Charente-Maritime, France) Using Synchrotron Microtomography Linked with Palaeoecology

We report exceptionally well-preserved plant remains ascribed to the extinct conifer Glenrosa J. Watson et H.L. Fisher emend. V. Srinivasan inside silica-rich nodules from the Cenomanian of the Font-de-Benon quarry, Charente-Maritime, western France. Remains are preserved in three dimensions and mainly consist of fragmented leafy axes. Pollen cones of this conifer are for the first time reported and in some cases remain connected to leafy stems. Histology of Glenrosa has not previously been observed; here, most of internal tissues and cells are well-preserved and allow us to describe a new species, Glenrosa carentonensis sp. nov., using propagation phase-contrast X-ray synchrotron microtomography, a non-destructive technique. Leafy axes consist of characteristic helically arranged leaves bearing stomatal crypts. Glenrosa carentonensis sp. nov. differs from the other described species in developing a phyllotaxy 8/21, claw-shaped leaves, a thicker cuticle, a higher number of papillae and stomata per crypt. Pollen cones consist of peltate, helically arranged microsporophylls, each of them bearing 6–7 pollen sacs. The new high resolution tomographic approach tested here allows virtual palaeohistology on plants included inside a dense rock to be made. Most tissues of Glenrosa carentonensis sp. nov. are described. Lithological and palaeontological data combined with xerophytic features of Glenrosa carentonensis sp. nov. suggest that this conifer has been adapted to survive in harsh and instable environments such as coastal area exposed to hot, dry conditions.

Cyclones and the formation of plant beds in late Carboniferous tropical swamps

Rapid deposition of sediments over the Euramerican Carboniferous swamps has resulted in exceptionally well-preserved plant fossils that often contain fragments of both swamp- and levee-living plants. There is virtually no evidence that the fragments were the result of natural abscission; a fact emphasised by the presence of mature cones that are still full of spores, fern fronds that rarely appear withered or enrolled, and pteridosperm fronds with glandular trichomes still containing the remains of exudant. Very strong winds of cyclone intensity would have been needed to cause such damage to the vegetation while, at the same time, producing flooding with sediment-laden water.

A combined biogeochemical and palaeobotanical approach to study permafrost environments and past dynamics

When investigating past peatland processes and related carbon cycle dynamics, it is essential to identify and separate different peat environments: bogs, fens and permafrost, and their historical plant assemblages. Bog peat layers contain relatively well-preserved plant material for palaeoecological examination, whereas fen and permafrost peats are often highly humified, which in turn constrains reconstructions of past plant assemblages. Here, we analysed the chemical composition of arctic peat plateau plants to create a local reference training-set of plant biomarkers. We then combined palaeobotanical, biogeochemical and chronological analyses to one permafrost peat sequence collected from the East European Russian tundra (67°03′N, 62°57′E) to investigate past peatland dynamics and to evaluate the performance of the biomarker method in a highly decomposed permafrost environment. The results show that the chronologically constrained macrofossil analysis provided most of the essential information about the peatland succession. However, a more robust reconstruction of the past peatland dynamics was achieved by combining palaeobotanical and biogeochemical data sets. The similarity of the lipid biomarker distributions of the arctic and boreal peatland plants also implies that any established modern biomarker training-set of peatland plants could be applied universally to palaeoecological studies on peat sediments.

Neuropterid fossil plants from the basal part of the Middle Carboniferous Manhang Formation in the Taebaek area, Korea and their significance

Some well-preserved neuropterid fossil plants were abundantly found in dark gray shale beds of lowermost basal part of the Middle Carboniferous Manhang Formation, which occur in the road cuts of Route 35 near the Hyeobsim Bridge in the Jangseong area, Taebaek City, Gangwon Province, Korea. The fossil plants include three species of Paripteris Gothan: P. gigantea (Sternberg), P. kaipingiana (Sze), and P. otozamioides (Sze and Lee). The latter two species were newly discovered and firstly described from the Korean Peninsula. The present fossil plants are the oldest land vascular plant fossils in the Republic of Korea. Based on the world-wide geologic range of these fossil plants, the basal part of the Manhang Formation in the Taebaek area corresponds to the upper Namurian stage of the Middle Carboniferous Period in age. This age assignment means that the deposition of the Manhang Formation started when the Middle Carboniferous sea transgressed on the Sino-Korean Craton.

Herd structure in Late Cretaceous polar dinosaurs: A remarkable new dinosaur tracksite, Denali National Park, Alaska, USA

The discovery of a new tracksite of mostly hadrosaurid dinosaur footprints, made by a herd living in an ancient high-latitude continental ecosystem, provides insight into the herd structure and behavior of northern polar dinosaurs and perspective on populations of large-bodied herbivores in an Arctic greenhouse world. This tracksite occurs in the Upper Cretaceous Cantwell Formation in the Alaska Range (Denali National Park, Alaska, United States), and it is the largest tracksite known from this far north. Preservation of the tracksite is exceptional: most tracks, regardless of size, contain skin impressions and they co-occur with well-preserved plant fossils and invertebrate trace fossils of terrestrial and aquatic insects. Statistical analyses of the tracks show that individuals of four different age classes of hadrosaurids lived together in a large social group. Our research results independently corroborate the growth curve for hadrosaurids proposed by paleohistologists that suggests that these dinosaurs experienced a period of rapid growth early in their life history.

Peatland ferruginization during late Quaternary in the Uberaba Plateau (South-Eastern Brazil)

Due to the poor preservation of old peat formations and the limited research developed on them, the contribution of peat oxidation to the global C cycle at geological scales is poorly understood. Iron duricrusts containing abundant well-preserved plant structures have been reported above Humic Gleysols in the Uberaba Plateau (Brazil). We show that the iron accumulation results from an in-situ impregnation of peat, fast enough to preserve the plant structures. The formation of iron oxides results from two processes: precipitation in the pores and C/Fe replacement. The iron duricrusts were probably triggered by oxidation of the peatland following dry climatic events during the last 50 kyr. The large amount of iron dissolved in peatland waters was immobilized contemporaneously with the destruction of organic matter. The oxidation of organic matter from the lower peat, dated at ca 24–27 kyr BP, may have released between 0.08 and 2.26 kg CO2 m−2 yr−1 in the atmosphere. These rates are in a good agreement with present-day measurements of CO2 release from drained peatlands. Although peatland formation has been identified as a significant contributor to the global CO2 uptake, our findings suggest that natural peatland oxidation should also be considered as a source of atmospheric CO2 during past climate change.

Yuzhou Flora—A hidden gem of the Middle and Late Cathaysian Flora

The Yuzhou Flora of the southern North China Platform possesses the typical regional features of the Middle and Late Cathaysian Flora. For a long time during the Permian, this area was located on shoreline marine tidal flats and deltas at low latitudes with a warm and humid climate. Consequently, many successive layers with abundant well-preserved plant fossils and a complete evolutionary sequence were developed. This is a unique and ideal place to study the Middle and Late Cathaysian Flora. We have recognized 111 genera and 307 species from this flora. The rapid morphological evolution and uninterrupted stratigraphic succession of Lobatannularia (Sphenophytes) make this group one of the bases for biostratigraphic divisions of the Permian System of the North China Platform. Ninety percent of Pteridophytes belong to the order Marattiales, which are well developed during the early and middle stages of the Yuzhou Flora but experience a sudden decline during the late stage. Ancient Pteridospermatophytes only flourished during the Middle Permian whereas advanced Peltaspermales are extremely well developed at the end of the early Late Permian. Among them Shenzhouphyllum is one of characteristic elements in the late stage of the Yuzhou Flora. The Cycadophytes evolved relatively early in this area and they differentiated and proliferated during the late Middle to early Late Permian. The number of species of Ginkgophytes is small but this group is extremely abundant, especially in the early Late Permian. The Gigantopteridales (preangiosperms) is a very important and unique group in the Yuzhou Flora. Based upon their venation and leaf architecture, this group can be divided into three evolutionary stages, i.e., appearance and differentiation, first flourishing, and second flourishing and sudden disappearance, which form the basis for biostratigraphic division and correlation of the Permian System of the North China Platform. Based upon the evolutionary trend of venation pattern and leaf architecture, we propose some taxonomic changes at the generic level. The Yuzhou Flora emerged at the middle Early Permian (Zisongian) and suddenly disappeared at the early Late Permian (Wujiapingian). It is later replaced by the Euro-American Zechstein flora in the late Late Permian. The Yuzhou Flora is divided into three (early, middle and late) stages based upon the cyclic development of its plant groups. Five fossil plant assemblage zones are recognized from the Yuzhou Flora based upon the succession of each group and their combined characters in different layers.

An Early Permian Glossopteris flora from the Umrer Coalfield, Wardha Basin, Maharashtra, India

Tewari, R., Pandita, S.K., Agnihotri, D., Pillai, S.S.K. & Bernardes-De-Oliveira, M.E.C., September 2012. An Early Permian Glossopteris flora from the Umrer Coalfield, Wardha Basin, Maharashtra, India. Alcheringa 36, 359–376. ISSN 0311-5518. A rich and well-preserved Glossopteris-dominated plant fossil assemblage is described from the Barakar Formation of the Makardhokra and Umrer open-cast projects, Umrer Coalfield, Nagpur District, Wardha Basin, Maharashtra, India. The assemblage includes equisetalean axes, cordaitalean leaves (Noeggerathiopsis hislopii), Gangamopteris clarkeana and diverse Glossopteris leaves and a fertile organ assigned to Scutum sp. cf. S. leslii. The flora, although similar to that of the Barakar Formation of the Damodar Basin complex (the reference basin system with respect to the qualitative and quantitative distribution of Indian Permian plant taxa), exhibits unique characteristics and is Artinskian to Kungurian in age. Besides supplementing knowledge of the broader Wardha Basin flora, this is the first systematic documentation of the Glossopteris flora from the Barakar Formation of this basin.

A new flora from the Upper Permian of Bletterbach (Dolomites, N-Italy)

A new fossiliferous horizon from the famous Bletterbach area is described. The new megafossil locality of late Permian age yields well-preserved plant megafossils, as well as cuticles and in situ pollen. In the flora representatives of the horsetails, seed ferns (Sphenopteris, Lepidopteris, Peltaspermum), putative cycadophytes (two types of Taeniopteris), ginkgophytes (three different leaf types) and conifers (Ortiseia, Pseudovoltzia, Quadrocladus, Pagiophyllum) were distinguished. Remains of doubtful botanical attribution comprise Dicranophyllum-like leaves and Leptostrobus-type of female fructifications as well as permineralized wood and charcoal. Remains of lycophytes reported from the Bletterbach cannot be confirmed. Some of these groups are recorded for the first time from the Bletterbach.

Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

Abstract. Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the major trends in cultural evolution of prehistoric peoples that inhabited the region.

Mangrove-bearing limestone from the Eocene Dammam Formation, Arabian Gulf: implications for the mangrove dispersal controversy

Fossil mangrove remains are found within the shallow carbonate strata of the Middle Eocene Dammam Formation of the Arabian Gulf. This formation is of wide distribution across most eastern parts of the Arabian Platform and represents the terminal stages of the Tethys Sea. The stand consists of well-preserved mangrove plant molds with the associated fossils of large foraminifera, gastropods, and barnacles. It forms part of carbonate ridges that circumscribe a present-day mangrove stand in Al-Khor estuary, NW Qatar. The two systems are comparable in many aspects in terms of sediment characterization and their faunal and flora contents. This finding supports the notion that mangrove ecosystems were common in the region at least since the Early Eocene and in alliance with the vicariance hypothesis, which states that earliest mangrove was restricted to the Tethys Sea.