Protoplasma最新文献

Skink, anguid, and pygopod lizards possess an extremely flat skin, imparting a compact and solid body and shining surface that facilitates their slider and/or fossorial movements. The present morphological study, conducted using immunohistochemistry and electron microscopy, has analyzed the microscopical morphology of extremely overlapped scales in different lizards, including species with limb reduction (scincids such as Lerista bougainvilli, Scincella lateralis, Lampropholis delicata) or legless (pygopods such as Lialis burtonis and Delma molleri and the anguid Anguis fragilis). The outer surface of the epidermis shows different micro-structures of the Oberhautchen layer containing corneous beta-proteins (CBPs) with variable immunoreactivity for these proteins. The beta-layer is relatively thick in most of these species, probably in relation to the resistance against strong mechanical forces acting on scales during the movements on harsh substrates. The scincid and anguid lizards also possess and regenerate osteoderms that reinforce scales flatness and mechanical resistance during the serpentiform or fossorial movements of these reptiles. Osteoderms are absent in pygopods. Roundish cells with a granular content are detected in the deep hinge region of scales in Lerista and Lampropholis skinks. Whether these cells may secrete substances that facilitate scale anti-friction and also determine shining of the skin surface remains to be shown.

Purple acid phosphatases (PAPs) play a vital role in plant phosphorus nutrition, serving as a crucial family of metallo-phosphoesterase enzymes. This research aimed to identify the PAP genes from the A/B/D genomes of Triticum aestivum to elucidate evolutionary mechanisms of the gene family in plants and provide genomic information for subsequent research on phosphorous-use efficiency in wheat crops. In total, 105 PAP genes (TaPAPs) were identified from the A/B/D genomes by using the Arabidopsis thaliana and Oryza sativa PAP protein sequences as queries for BLASTP against the wheat protein database. The TaPAPs were grouped into six subfamilies, Ia (17), Ib (26), IIa (11), IIb (30), IIIa (12), and IIIb (9), based on their similarities in the structure of genes and the presence of conserved protein motifs. A majority of TaPAPs were derived from tandemly (20) or segmentally (87) duplicated, with the homoeologous chromosomes 5A/B/D harboring the most duplicated PAP genes. Further analysis indicated that TaPAPs were responsible for the modulation of seed, root, and leaf development and hormone synthesis and signaling, as well as plant responses to abiotic stresses, including low temperatures, drought, and anaerobic conditions. Nine TaPAPs (TaPAP9-4A/4B/4D, TaPAP24-6A/6B/6D, and TaPAP28-7A/7B/7D) were constitutively expressed in diverse tissues such as root, shoot, leaf, spike, and seed, while the remaining genes exhibited tissue-specific expression patterns. Concerning the response to phosphate (Pi) deprivation, 57 TaPAPs were highly expressed in roots under Pi stress, including TaPAP31-4A, 4B, and 4D homeologs from the subfamily IIIb. A TaPAP31-4A transgene in A. thaliana promoted plant growth and development while increasing plant resistance to Pi-deficiency stress by enhancing the secretion of phosphatase. These discoveries provide a scientific foundation for comprehending the role of TaPAPs, offering valuable insights for identifying additional candidate genes and fostering the development of new wheat varieties with enhanced tolerance to low phosphorus conditions.

In response to the restrictions imposed by their epiphytic habit, orchids have developed structural traits that allow greater efficiency in water uptake and use, such as a complex adventitious root system with velamen. The composition of cell wall of this specialized epidermis can be altered according to the substrate to which it is fixed, influencing wall permeability, absorption, and storage of water in roots. The current study aimed to evaluate the cell wall composition of adventitious roots of Vanilla phaeantha (Orchidaceae) that grow attached to the phorophyte, fixed in the soil, or hung free. Immunocytochemical analyses were used to determine the protein, hemicellulose, and pectin composition of the cell walls of aerial and terrestrial roots. We observed that pectins are present in the different tissues of the aerial roots, while in the terrestrial roots, they are concentrated in the cortical parenchyma. The deposition of xyloglucans, extensins, and arabinogalactans was greater in the epidermis of the free side of the roots attached to the phorophyte. The strong labeling of pectins in aerial roots may be related to the influx of water and nutrients, which are generally scarce in this environment. The arrangement of hemicelluloses and proteins with the pectins may be associated with increased cell rigidity and sustainability, a feature of interest for the aerial roots. In summary, the habit of roots can interfere with the non-cellulosic composition of the cell walls of V. phaeantha, possibly related to changes in cell functionality.

Sooty moulds are saprophytic epiphytic fungi that grow mostly on insect secretions, but they can also be associated with plant secretions. In this study, we aimed to describe de interaction of Capnodium alfenasii sooty mould with the extrafloral shoot nectaries of Azadirachta indica. Anatomical and histochemical studies were carried out on serial sections of extrafloral shoot nectaries of A. indica without and with C. alfenasii infestation. The total soluble sugar content of the secreted nectar was determined, and the conidial germination of the fungus in distilled water and in dextrose and nectar solutions was evaluated. The shoot nectaries of A. indica are elongated structures that occur in pairs near the base of the petiole. The exuded nectar contains an average of 534.8 µg of total soluble sugars per µL of nectar and provides ideal conditions for conidial germination and fungal growth. C. alfenasii hyphae grow on the nectary, penetrate through breaks in the cuticle, travel under the cuticle and penetrate the secretory tissue by inter- and intracellular routes. The present report is the first to describe the interaction of C. alfenasii with the A. indica nectary, including the penetration of hyphae into nectariferous tissues and the plant defence mechanisms.

Germination is an essential phenomenon in the life cycle of plants, and a variety of external and internal factors influence it. Fire and the produced smoke have been vital environmental stimulants for the germination of seeds in many plant species, like Leucospermum cordifolium and Serruria florida. These plants do not germinate at all if fire and smoke are not present. This phenomenon of germination in plant species has existed in the ecosystem since ancient times. Various studies to study the response of seeds to smoke and its extracts have been undertaken for stimulation of germination by burning various plant materials and bubbling the smoke produced through water. The application of plant-derived smoke and smoke water is well known for promoting germination, breaking dormancy, and checking abiotic stress. This significantly indicates that plant-derived smoke contains some bioactive metabolites responsible for the physiological metabolism of seed germination and is involved in enhancing seed vigor. The present review deals with the ancient use of smoke and smoke extracts for seed priming, the cost-efficient method of its preparation, the mode of action of karrikins relating to its perception by plants, and its significant effects on various crops, including its ability to check biotic and abiotic stresses.

Many insect-induced galls are considered complex structures due to their tissue compartmentalization and multiple roles performed by them. The current study investigates the complex interaction between Nothofagus obliqua host plant and the hymenopteran gall-inducer Espinosa nothofagi, focusing on cell wall properties and cytological features. The E. nothofagi galls present an inner cortex with nutritive and storage tissues, as well as outer cortex with epidermis, chlorenchyma, and water-storing parenchyma. The water-storing parenchyma cells are rich in pectins, heteromannans, and xyloglucans in their walls, and have large vacuoles. Homogalacturonans contribute to water retention, and periplasmic spaces function as additional water reservoirs. Nutritive storage cell walls support nutrient storage, with plasmodesmata facilitating nutrient mobilization crucial for larval nutrition. Their primary and sometimes thick secondary cell walls support structural integrity and act as a carbon reserve. The absent labeling of non-cellulosic epitopes indicates a predominantly cellulosic nature in nutritive cell walls, facilitating larval access to lipid, protein, and reducing sugar-rich contents. The nutritive tissue, with functional chloroplasts and high metabolism-related organelles, displays signs of self-sufficiency, emphasizing its role in larval nutrition and cellular maintenance. Overall, the intricate cell wall composition in E. nothofagi galls showcases adaptations for water storage, nutrient mobilization, and larval nutrition, contributing significantly to our understanding of plant-insect interactions.

Rhizochromulina is a genus of unicellular dictyochophycean algae (Heterokontophyta), comprising a single species R. marina and numerous strains. Recently, we described the first arctic rhizochromuline-Rhizochromulina sp. strain B44. Amoeboid cells of this algae are able to transform into flagellates, and this transition can be triggered by prolonged mechanical disturbance. Thin branching pseudopodia of the neighboring rhizochromuline cells fuse to form a meroplasmodium. The pseudopodia contain microtubules, but do not contain actin microfilaments; actin forms the cytoplasmic cytoskeleton and extends only to the bases of the pseudopodia. Microtubule-driven pseudopodia are characteristic to a plethora of eukaryotes, but the role of microtubular and actin cytoskeleton in locomotion of these organisms remains poorly understood. We conducted a series of experiments where amoeboid cells of Rhizochromulina sp. B44 were treated with either 10 µM nocodazole, 10 µM latrunculin B, or both drugs simultaneously. Cellular locomotion was captured on camera, tracked, and then analyzed with the help of the generalized additive mixed model. The obtained results indicate that both drugs, when applied separately, decrease the motility of the studied cells. Unexpectedly, the combined treatment had the opposite effect, as the cells became more motile. The analysis also revealed a non-linear pattern of relationship between motility of amoeboid cells of rhizochromulines and density of their population.

Sucrose (SUC) is a signaling molecule with multiple physiological functions. G protein is a kind of receptor that converts extracellular first messenger into intracellular second messenger. However, it is little known that SUC interplays with G protein signaling in maize thermotolerance. In this work, using maize seedlings as materials, the interplay between SUC and G protein signaling in maize thermotolerance was investigated. The results indicate that heat stress-decreased survival percentage and tissue viability of the seedlings was mitigated by SUC. Similarly, heat stress-increased malondialdehyde content and electrolyte leakage also was reduced by SUC. These findings show that SUC can potentially enhance thermotolerance in maize seedlings. Also, SUC-enhanced thermotolerance was abolished by suramin (G protein inhibitor) and N-ethylmaleimide (SUC transport inhibitor), but enhanced by 3-O-methyl-D-glucose (G protein activator), indicating the interplay of SUC and G protein signaling in maize thermotolerance. To investigate the possible mechanism behind SUC-G protein interaction in enhancing maize thermotolerance, osmoregulation in mesocotyls of seedlings were evaluated before and after heat stress. The results suggest that osmolytes (SUC, glucose, fructose, total soluble sugar, proline, and glycine betaine) contents in mesocotyls under non-heat and heat stress were increased by SUC in varying degrees. Likewise, the osmolyte-metabolizing enzymes (sucrose-phosphate synthase, sucrose synthase, pyrroline-5-carboxylate synthase, ornithine aminotransferase, betaine-aldehyde dehydrogenase, and trehalase) activities were enhanced by SUC. Analogously, ZmSPS1, ZmSUS6, ZmP5CS, ZmOAT, ZmBADH, and ZmTRE1 expression in mesocotyls was up-regulated by SUC to different extent. These findings illustrate that the functional crosstalk of sucrose and G protein signaling in maize thermotolerance by modulating osmoregulation system.

Plant anatomical and histochemical studies are concerned with the structural organization of tissues as well as localization of various metabolites and enzyme activity inside cells and tissues. Traditionally, rotary microtomes are used for paraffin and resin-embedded samples which provide excellent preservation of tissue morphology but removes enzymes, lipid components, and various specialized metabolites. Freeze sectioning apparently remained unexplored in plant histology because of the presence of rigid cell walls and highly vacuolated cytoplasm in plant tissues. In this study, we have described a simple cryostat-based sectioning technique using polyethylene glycol (PEG) as embedding medium after glycerol infiltration that protects the plant tissues from freezing and thawing damage. We have also compared the suitability of inexpensive aqueous PEG solution as compared to commercially available optimal cutting temperature (OCT) medium and obtained identical microscopic images. Diverse plant organs from different genera were sectioned to check the application of this method in plant anatomical studies. In all the cases, cross sections were shown to be well preserved similar to paraffin-embedded plant tissues. In addition, histochemical analyses showed retention of metabolites and even enzymes in the tissues, which can make this method an alternate choice in cryo-microtomy replacing the expensive OCT medium.

Microscopic analyses of cytoskeleton organization are crucial for understanding various cellular activities, including cell proliferation and environmental responses in plants. Traditionally, assessments of cytoskeleton dynamics have been qualitative, relying on microscopy-assisted visual inspection. However, the transition to quantitative digital microscopy has introduced new technical challenges, with segmentation of cytoskeleton structures proving particularly demanding. In this study, we examined the utility of a deep learning-based segmentation method for accurate quantitative evaluation of cytoskeleton organization using confocal microscopic images of the cortical microtubules in tobacco BY-2 cells. The results showed that, although conventional methods sufficed for measurement of cytoskeleton angles and parallelness, the deep learning-based method significantly improved the accuracy of density measurements. To assess the versatility of the method, we extended our analysis to physiologically significant models in the context of changes in cytoskeleton density, namely Arabidopsis thaliana guard cells and zygotes. The deep learning-based method successfully improved the accuracy of cytoskeleton density measurements for quantitative evaluations of physiological changes in both stomatal movement in guard cells and intracellular polarization in elongating zygotes, confirming its utility in these applications. The results demonstrate the effectiveness of deep learning-based segmentation in providing precise and high-throughput measurements of cytoskeleton density, and has the potential to automate and expedite analyses of large-scale image datasets.