Palisade Parenchyma Research Articles

Macro-microscopic and HPTLC Atlas of Canavalia gladiata (Jacq.) DC. Fruit

Pharmacognosy Research,2023,15,2,277-287.DOI:10.5530/pres.15.2.030Published:February 2023Type:Original Article Authors:Susikumar Sundharamoorthy, Gokula Kannan Sundharamoorthy, Achintya Kumar Mandal, Shakila Ramachandran, Senthilvel Govindaraju, and Sunil Kumar Koppala Narayanan Author(s) affiliations:Susikumar Sundharamoorthy1,*, Gokula Kannan Sundharamoorthy2, Achintya Kumar Mandal1, Shakila Ramachandran1, Senthilvel Govindaraju1, Sunil Kumar Koppala Narayanan1 1Siddha Central Research Institute, Central Council for Research in Siddha, Ministry of AYUSH, Govt. of India, A. A. Hospital Campus, Arumbakkam, Chennai, Tamil Nadu, INDIA. 2Department of Plant Biology and Biotechnology, Ramakrishna Mission Vivekananda College, Mylapore, Chennai, Tamil Nadu, INDIA. Abstract:Background: Canavalia gladiata (Jacq.) DC. (Family Leguminosae) is a large annual or perennial climber with a terete glabrous stem, native to Indo-Malaysian and also distributed in tropical, subtropical regions. C. gladiata (Jacq.) DC. is generally confused with another closely related species i.e. C. ensiformis (Linn.) DC (Jack bean). The tender pods of both the above species have close similarity in morphology, especially shape and size of fruit, therefore it is difficult to differentiate on their vegetative and also fruiting stages. The plant C. ensiformis mentioned as a synonym of C. gladiata in many of the earlier literature though they are 2 different taxa. Some authors published different colour seeds in the name of C. gladiata. It is doubtful if C. ensiformis (Linn.) DC. or C. gladiata (Jacq.) DC was studied during that analysis. Objectives: A systematic pharmacognostical study has been executed to identify the correct botanical source. Materials and Methods: All the studies were carried out by standard procedures in Pharmacopoeias and other authentic literature. Results: Macroscopically surface characters followed by odour and taste, anatomically TS of the pericarp, plecenta, testa, cotyledon and radical, powder microscopically epidermal cells with stomata and prismatic crystal cystolith, trichomes, testa palisade cells, sclereids with different shape and size, brownish content, starch grains, tracheids, fibres and prismatic crystals of calcium oxalate are the unique diagnostic characters observed. HPTLC with different spots having unique Rf values in the pericarp, testa, cotyledon and seeds will be helpful for critical identification of the species. Conclusion: The findings of the present study will be helpful in the identification and differentiation of related species as the whole drug or in powder form. Keywords:Jack bean, Seed anatomy, Sword bean, Vegetable Crude Drug.View:PDF (1.49 MB)

Changes in the morphology traits, anatomical structure of the leaves and transcriptome in Lycium barbarum L. under salt stress.

Salt stress directly affects the growth of plants. The limitation of leaf grow is among the earliest visible effects of salt stress. However, the regulation mechanism of salt treatments on leaf shape has not been fully elucidated. We measured the morphological traits and anatomical structure. In combination with transcriptome analysis, we analyzed differentially expressed genes (DEGs) and verified the RNA-seq data by qRT-PCR. Finally, we analyzed correlation between leaf microstructure parameters and expansin genes. We show that the leaf thickness, the width, and the leaf length significantly increased at elevated salt concentrations after salt stress for 7 days. Low salt mainly promoted the increase in leaves length and width, but high salt concentration accelerated the leaf thickness. The anatomical structure results indicated that palisade mesophyll tissues contribute more to leaf thickness than spongy mesophyll tissues, which possibly contributed to the increase in leaf expansion and thickness. Moreover, a total of 3,572 DEGs were identified by RNA-seq. Notably, six of the DEGs among 92 identified genes concentrated on cell wall synthesis or modification were involved in cell wall loosening proteins. More importantly, we demonstrated that there was a strong positive correlation between the upregulated EXLA2 gene and the thickness of the palisade tissue in L. barbarum leaves. These results suggested that salt stress possibly induced the expression of EXLA2 gene, which in turn increased the thickness of L. barbarum leaves by promoting the longitudinal expansion of cells of the palisade tissue. This study lays a solid knowledge for revealing the underlying molecular mechanisms of leaf thickening in L. barbarum in response to salt stresses.

Study of Camellia sinensis diploid and triploid leaf development mechanism based on transcriptome and leaf characteristics.

Polyploidization results in significant changes in the morphology and physiology of plants, with increased growth rate and genetic gains as the number of chromosomes increases. In this study, the leaf functional traits, photosynthetic characteristics, leaf cell structure and transcriptome of Camellia sinensis were analyzed. The results showed that triploid tea had a significant growth advantage over diploid tea, the leaf area was 59.81% larger, and the photosynthetic capacity was greater. The morphological structure of triploid leaves was significantly different, the xylem of the veins was more developed, the cell gap between the palisade tissue and the sponge tissue was larger and the stomata of the triploid leaves were also larger. Transcriptome sequencing analysis revealed that in triploid tea, the changes in leaf morphology and physiological characteristics were affected by the expression of certain key regulatory genes. We identified a large number of genes that may play important roles in leaf development, especially genes involved in photosynthesis, cell division, hormone synthesis and stomata development. This research will enhance our understanding of the molecular mechanism underlying tea and stomata development and provide a basis for molecular breeding of high-quality and high-yield tea varieties.

Variations in leaf anatomical characteristics drive the decrease of mesophyll conductance in poplar under elevated ozone.

Decline in mesophyll conductance (gm ) plays a key role in limiting photosynthesis in plants exposed to elevated ozone (O3 ). Leaf anatomical traits are known to influence gm , but the potential effects of O3 -induced changes in leaf anatomy on gm have not yet been clarified. Here, two poplar clones were exposed to elevated O3 . The effects of O3 on the photosynthetic capacity and anatomical characteristics were assessed to investigate the leaf anatomical properties that potentially affect gm . We also conducted global meta-analysis to explore the general response patterns of gm and leaf anatomy to O3 exposure. We found that the O3 -induced reduction in gm was critical in limiting leaf photosynthesis. Changes in liquid-phase conductance rather than gas-phase conductance drive the decline in gm under elevated O3, and this effect was associated with thicker cell walls and smaller chloroplast sizes. The effects of O3 on palisade and spongy mesophyll cell traits and their contributions to gm were highly genotype-dependent. Our results suggest that, while anatomical adjustments under elevated O3 may contribute to defense against O3 stress, they also cause declines in gm and photosynthesis. These results provide the first evidence of anatomical constraints on gm under elevated O3 .

The structure of the eggshell and eggshell membranes of Crocodylus niloticus.

The macro- and microstructure, elemental composition, and crystallographic characteristics of the eggshell and eggshell membranes of the Crocodylus niloticus egg was investigated using optical and electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and computerised tomography. The translucent ellipsoid egg is composed of two basic layers, the outer calcified layer referred to as the shell and an inner organic fibre layer, referred to as the shell membrane. The outer inorganic calcite shell is further divided into an external, palisade and mammillary layers with pore channels traversing the shell. The external layer is a thin layer of amorphous calcium and phosphorus, the underlying palisade layer consist of irregular wedge-shaped crystals composed calcite with traces of magnesium, sodium, sulphur and phosphorus. The crystals are mostly elongated, orientated perpendicular to the shell surface ending in cone-shaped knobs, which forms the inner mammillary layer. The elemental composition of the mammillae is like that of the palisade layer, but the crystal structure is much smaller and orientated randomly. The highest number of mammillae and shell pores are found at the equator of the egg, becoming fewer towards the egg poles. The shell thickness follows the same pattern, with the thickest area located at the equator. The eggshell membrane located right beneath and embedded in the mammillary layer of the shell; it is made up of unorganised fibre sheets roughly orientated at right angles to one another. Individual fibres consist of numerous smaller fibrils forming open channels that run longitudinally through the fibre.

Comparative Analysis of Morphological, Physiological, Anatomic and Biochemical Responses in Relatively Sensitive Zinnia elegans ‘Zinnita Scarlet’ and Relatively Tolerant Zinnia marylandica ‘Double Zahara Fire Improved’ under Saline Conditions

Salinity is one of the major abiotic stresses in plants. The aim of the present study was to determine the effects of salinity on relatively sensitive Zinnia elegans Jacq. ‘Zinnita Scarlet’ and relatively tolerant Zinnia marylandica D.M. Spooner et al. ‘Double Zahara Fire Improved’ through a comparative analysis of morphological, physiological, anatomic, and biochemical traits. Plants were irrigated at five levels of salt concentrations (0 [control], 50, 100, 150, 200 mM NaCl) for three weeks at one-day intervals in pots under greenhouse conditions. The effects of salinity stress on plant growth parameters, ion leakage, the loss of turgidity, minimum fluorescence (FO’), plant nutrient elements, leaf anatomic parameters, stoma response to the application of light and abscisic acid perfusion, proline content, chlorophyll a, b and total chlorophyll, and carotenoid content were investigated. Differences in the stages and levels of plant response in the relatively sensitive and relatively tolerant cultivar were determined. Proline accumulation appeared to be higher in Double Zahara Fire Improved (D.Za.F.I.) than Zinnita Scarlet (Zi.S.) in the low concentration of salinity. After the application of abscsic acid perfusion to intact leaf surfaces, the stomata of the relatively tolerant cultivar D.Za.F.I. closed earlier (7 min) than Zi.S. (29 min). Ion leakage (32.3%) and Na accumulation (0.9%) in the aerial parts increased dramatically for Zi.S in the 50 mM NaCl treatment. Moreover, values of plant growth parameters, minimum fluorescence (FO’), photosynthetic pigments, and plant nutrient elements all showed a greater decreasing percentage in Zi.S. compared to D.Za.F.I. Stomatal densities for both the abaxial and adaxial surfaces of the leaf decreased in parallel with the increase in salt stress. Palisade parenchyma cell height and leaf thickness values decreased in Zi.S. as salinity increased. In D.Za.F.I., leaf thickness increased by up to 100 mM NaCl while the height of palisade parenchyma cells decreased under high salt stress conditions (100 mM and above). Recommendations for future research include molecular-level evaluations and the study of how to increase salt tolerance in these potentially valuable ornamental cultivars.

Calcium silicate mitigates the physiological stress induced by 6-benzylaminopurine during the in vitro multiplication of Quercus robur

For Quercus species, efficient large-scale proliferation may be dependent on or enhanced by exposure to synthetic cytokinins, such as 6-benzylaminopurine (BAP). However, it can also induce physiological disturbances. In contrast to BAP, the addition of silicon to the medium has been carried out to improve the characteristics related to growth and physiology during in vitro culture. We aimed to assess the morphophysiological modulations in Quercus robur shoots exposed to BAP and calcium silicate (CaSiO3), used alone or synergistically, during in vitro multiplication. Shoots were cultured with BAP at 0 or 3.50 μM combined with CaSiO3 concentrations at 0, 6, 12, or 18 μM. The morphophysiological traits and photosynthetic apparatus functioning were quantified at 46 days of growth. De novo shoot regeneration was verified only in explants cultured under BAP exposure. Shoots cultured with CaSiO3 supplementation and BAP-free media had the largest leaf area, which was a response to larger epidermal cells. Additionally, thicker tissues (adaxial epidermis, palisade, and spongy parenchyma) were observed in leaves that grew under CaSiO3. BAP supplementation induced shoots with a ∼18% reduction of the contents of chlorophyll and phenolic compounds. BAP also induced harmful effects on the photosynthetic apparatus, reducing 8% of the fraction of oxygen-evolving complex (OEC centers) and 33% of active reaction centers (RC/CSm). Such results were attenuated when the shoots were co-exposed to CaSiO3. The positive effects of CaSiO3 were confirmed by the ≥ 42% increase in the total performance index (PI(TOTAL)). The addition in the concentration range between 12 and 18 μM CaSiO3 can mitigate the harmful effects of BAP during the in vitro multiplication phase of Q. robur.

A pharmacognostic approach, including phytochemical and GC-MS analysis, targeted towards the authentication of Strobilanthes jomyi P. Biju, Josekutty, Rekha & J.R.I.Wood

The genera Strobilanthes Blume have a rich history in therapeutic culture all over the world. Asian countries like India, China, Myanmar and Thailand still use Strobilanthes genus-based medicinal preparations for various diseases. Strobilanthes jomyi is a newly discovered species from Kerala, India. Some tribal communities of Kasaragod district still use S. jomyi leaf extract as a wound healing medication. The current study aims to investigate the pharmacognostic, phytochemical and GC-MS analysis of the leaves, stems and roots of S. jomyi. The microscopic, macroscopic, organoleptic, fluorescent, phytochemicals and GC-MS analysis of the leaves, stem, and root of S. jomyi were estimated using various standard protocols. The macroscopic and microscopic characters of leaves revealed the presence of non-glandular trichomes with paracytic stomata in the leaves. The transverse section of the stem and petiole showed the presence of raphides and the root showed the presence of tannin cells. Cystoliths were observed only in the petiole. Powder morphology of leaves, stems and roots revealed the presence of fibers, trichomes, palisade cells, spiral xylem vessels, bordered pit vessels and raphides. The vegetative part of S. jomyi powder exhibited various fluorescent coloration based on numerous chemical treatments along with different tastes, smells, colors and textures by organoleptic assays. Qualitative phytochemical analysis of different vegetative parts revealed the presence of flavonoids and other phytochemicals. GC-MS study revealed that lupeol a significant bioactive compound was present in all the vegetative parts of S. jomyi. The results acquired from this study can be used for the standardization, identification, quality and purity check of plant samples.

Thickness of Leaf Anatomical Tissue Dicot Ornamental Plants at Different Light Intensities

Different light intensities affect the leaf anatomy. This study aims to measure the thickness of the anatomical tissue of the leaves of six types of dicot ornamental plants at different light intensities. This study used a quantitative experimental method with a completely randomized factorial design (CRD-Factorial). This design consisted of two factors, namely the main factors were six types of plants, namely Codiaeum variegatum (L.) A. Juss., Bougainvillea glabra Choisy, Tabernaemontana divaricata (L.) R, Br. Ex Roem. & Schult., Syzygium paniculatum Gaertn, Excoecaria cochinchinensis Lour., and Aerva sanguinolenta BI. The second factor is the different light conditions (open and shading) with three replications. Parameters measured were total leaf anatomical tissue thickness, upper and lower epidermis, palisade, and spongy using a modified paraffin method from Johansen. Data were analyzed using the CRD-Factorial ANOVA model followed by the LSD test. Correlation done between palisade, spongy, and lower epidermis thickness with total tissue thickness. The results showed that the leaf anatomy of six types of dicot ornamental plants varied. All plants have one layer of upper and lower epidermis tissue. In Codiaeum variegatum (L.) A. Juss., Syzygium paniculatum Gaertn, and Excoecaria cochinchinensis Lour. has two layers of palisade tissue while the Bougainvillea glabra Choisy, Tabernaemontana divaricata (L.) R,Br. Ex Roem. & Schult. and Aerva sanguinolenta BI has one layer of palisade tissue. Meanwhile, the spongy tissue in all plants has one layer of tissue. The thickness of the leaf tissue decreased in the shading area along with the depletion of the palisade, spongy, and lower epidermis tissue as indicated by a correlation from moderately strong to very strong. Shrinkage of palisade tissue, sponges, and lower epidermis is a plant's attempt to get optimal light in shading areas. The more lower epidermis srink, the thickness of leaf become thin while the thickness of palisade and sponge varied so the thickness of total leaf from each species also varied.

Revisiting Vickers and Gorlin criteria in histopathological subtypes of ameloblastoma.

Ameloblastoma is a benign tumour of odontogenic epithelial origin arising from enamel organ tissue that has not undergone differentiation to the point of hard tissue formation. This study was conducted with an aim to provide a baseline data to analyse whether various histopathological variants of ameloblastoma satisfies all the characteristic histopathological features of Vickers and Gorlin criteria. A retrospective study of 25 cases of intraosseous ameloblastoma was carried out in the Department of Oral Pathology and Microbiology in accordance with the Institutional Ethics Committee. Histopathological slides of ameloblastoma subtypes were analysed microscopically to assess Vickers and Gorlin criteria. Statistical analysis was done using the Chi-square test. A P- value of < 0.05 was set for statistical significance. Presence of hyperchromatic nuclei was seen in all the variants (100%), except for the desmoplastic variant which showed only 60% positivity. Basal cell palisading, reverse polarity and subnuclear vacuolization were seen predominantly only in acanthomatous (100%), and follicular variants (83%). Vickers and Gorlin criteria have become an integral part of diagnosis of histopathological subtypes of ameloblastoma and should be applied vigilantly in the diagnosis as these may not always fulfill all the gold standard criteria when individual subtypes are assessed.

Anatomical and phytochemical studies and ethnomedicinal uses of Colchicum autumnale L.

Background: In the world, great importance is attached to the intensification of plants. To date, most medicinal plants are only partially used. In case of Colchicum autumnale L. currently mainly the corms are used for the extraction of alkaloids. The purpose of this study was to investigate the intensification of the use of this perspective plant reported from the study area. This article examines the anatomy and phytochemistry of leaf and corm of C. autumnale, which is grown as a medicinal crop in Uzbekistan. Methods: The leaves were fixed in 70% ethanol according to the generally accepted method; transverse and paradermal sections were examined on the fixed material. When studying the anatomical features of the leaf, preparations was formed by manually cutting a transverse section of the leaf were observed by a MOTIC V1 microscope. The slides were stained with glycerin jelly having safranin. Cells and tissues were measured using a micrometer MOB-15. To determine the amount of alkaloids contained in the leaves and in corms, a chemical analysis was carried out in the laboratory of alkaloids of the Institute of Chemistry of Plant Substances. Results: On the transverse section of the stomata of the leaves of Colchicum autumnale anomocytic type, 2-3 rows of parenchyma and palisade cells, the characteristic size of the stomata. The root structure of C. autumnale consists of 4-5 rows of corolla, 4 protoxylems and 1 metaxylem, and the presence of rhomboid calcium oxalate crystals in its parenchyma is a characteristic feature of the species. As a result of studying the chemical composition of the plant in the conditions of the Tashkent region, it was observed that the amount of alkaloids in the aerial part of the colchicum, in the leaves was 0.4% and in the corm 0.14%. Conclusion: The current work sought to resolve taxonomic issues involving species that share the majority of their physical characteristics and to clarify relationships between important taxa by utilizing leaf epidermal characteristics. As a result of chemical analysis, it was revealed that the amount of alkaloids in the leaves of Colchicum autumnale, introduced in the conditions of the Tashkent region (Uzbekistan), is higher than in natural regions. This proves that in the conditions of Uzbekistan it is possible to grow Colchicum and obtain high-quality raw materials. Key words: autumn crocus, meadow saffron, anatomy, phytochemistry, ethnomedicine.

Roles of type II H+-PPases and PPsPase1/PECP2 in early developmental stages and PPi homeostasis of Arabidopsis thaliana.

The regulation of intracellular pyrophosphate (PPi) level is crucial for proper morphogenesis across all taxonomic kingdoms. PPi is released as a byproduct from ~200 metabolic reactions, then hydrolyzed by either membrane-bound (H+-PPase) or soluble pyrophosphatases (PPases). In Arabidopsis, the loss of the vacuolar H+-PPase/FUGU5, a key enzyme in PPi homeostasis, results in delayed growth and a number of developmental defects, pointing to the importance of PPi homeostasis in plant morphogenesis. The Arabidopsis genome encodes several PPases in addition to FUGU5, such as PPsPase1/PECP2, VHP2;1 and VHP2;2, although their significance regarding PPi homeostasis remains elusive. Here, to assess their contribution, phenotypic analyses of cotyledon aspect ratio, palisade tissue cellular phenotypes, adaxial side pavement cell complexity, stomatal distribution, and etiolated seedling length were performed, provided that they were altered due to excess PPi in a fugu5 mutant background. Overall, our analyses revealed that the above five traits were unaffected in ppspase1/pecp2, vhp2;1 and vhp2;2 loss-of-function mutants, as well as in fugu5 mutant lines constitutively overexpressing PPsPase1/PECP2. Furthermore, metabolomics revealed that ppspase1/pecp2, vhp2;1 and vhp2;2 etiolated seedlings exhibited metabolic profiles comparable to the wild type. Together, these results indicate that the contribution of PPsPase1/PECP2, VHP2;1 and VHP2;2 to PPi levels is negligible in comparison to FUGU5 in the early stages of seedling development.

Structural and Physiological Traits of Compound Leaves of Ceratonia siliqua Trees Grown in Urban and Suburban Ambient Conditions.

Ceratonia siliqua L. (carob tree) is an endemic plant to the eastern Mediterranean region. In the present study, anatomical and physiological traits of successively grown compound leaves (i.e., the first, third, fifth and seventh leaves) of C. siliqua were investigated in an attempt to evaluate their growth under urban and suburban environmental conditions. Chlorophyll and phenolic content, as well as the specific leaf area of the compound leaves were determined. Structural traits of leaflets (i.e., thickness of palisade and spongy parenchyma, abaxial and adaxial epidermis, as well as abaxial and adaxial periclinal wall) were also investigated in expanding and fully expanded leaflets. Fully expanded leaflets from urban sites exhibited increased thickness of the lamina and the palisade parenchyma, while the thickness of the spongy parenchyma was thicker in suburban specimens. The palisade tissue was less extended than the spongy tissue in expanding leaflets, while the opposite held true for the expanded leaflets. Moreover, the thickness of the adaxial and the abaxial epidermises, as well as the adaxial and abaxial periclinal wall were higher in suburban leaflets. The chlorophyll content increased concomitantly with the specific leaf area (SLA) of both expanding and expanded leaflets, and strong positive correlations were detected, while the phenolic content declined with the increased SLA of expanding and expanded leaflets. It is noteworthy that the SLA of expanding leaflets in the suburban site was comparable to the SLA of expanded leaflets experiencing air pollution in urban sites; the size and the mass of leaf blades of C. siliqua possess adaptive features to air pollution. These results, linked to the functional structure of expanding and expanded successive foliar tissues, provide valuable assessment information coordinated with an adaptive process and yield of carob trees exposed to the considered ambient conditions, which have not hitherto been published.

Adaptive evolution of leaf anatomical features in mangrove Rhizophoraceae cues differential strategies of salt tolerance

The monophyletic mangrove Rhizophoraceae (tribe Rhizophoreae) group has been studied by leaf anatomical features to understand whether the adaptive strategies for salt tolerance are generalized or specific to species or genera (or clade). Thickness data from leaf and different layers in leaf cross-sectional view are acquired to discuss adaptive evolution in the tribe. An increase in leaf thickness is the most common phenomenon in mangroves. The development of thin to thick but always well-developed hypodermis layers in the leaves of Rhizophoreae is a strategic advantage to store water and prevent high-intensity light of solar irradiation. In contrast, the hypodermis layer in non-mangrove Carallia brachiata is rudimentary though thicker than some mangrove species. The existence of hypodermis in non-mangrove relatives of Rhizophoreae might pave their way to saline intertidal habitat. The clade bearing all the species of Bruguiera shows a decreasing trend of allocation to the hypodermis layer whereas an increasing trend was observed in case of the palisade layer. The positioning of chloroplasts deep into the elongated palisade cells in Bruguiera may minimize the photodamage effect. An efficient ultrafiltration mechanism in the Bruguiera clade may result in a slow accumulation of salts in mesophyll tissue and thereby allocation to the hypodermis layer is reduced. A lower palisade layer was developed in the ancestor of Ceriops and Kandelia. This layer is more developed in Kandelia than in Ceriops due to the presence of a thinner upper hypodermis layer in the former genus. The thin upper hypodermis is inefficient in preventing high-intensity light; consequently, the photodamage effect is likely in the upper palisade layer of Kandelia. The lower palisade layer possibly compensates photodamage effect of the upper palisade layer. Maximized allocation to the upper hypodermal layer in Rhizophora clade may indicate its highest salinity tolerance ability. The compact spongy layer in Rhizophoreae divulges their limited primary productivity in comparison to their terrestrial relative. The contrastive allotment of leaf layers in the species or genera (or clades) of Rhizophoreae cues different strategies of salt tolerance despite the fact that they originated from a common ancestor of saline intertidal habitat.

Dissecting succulence: Crassulacean acid metabolism and hydraulic capacitance are independent adaptations in Clusia leaves.

Succulence is found across the world as an adaptation to water-limited niches. The fleshy organs of succulent plants develop via enlarged photosynthetic chlorenchyma and/or achlorophyllous water storage hydrenchyma cells. The precise mechanism by which anatomical traits contribute to drought tolerance is unclear, as the effect of succulence is multifaceted. Large cells are believed to provide space for nocturnal storage of malic acid fixed by crassulacean acid metabolism (CAM), whilst also buffering water potentials by elevating hydraulic capacitance (CFT ). The effect of CAM and elevated CFT on growth and water conservation have not been compared, despite the assumption that these adaptations often occur together. We assessed the relationship between succulent anatomical adaptations, CAM, and CFT , across the genus Clusia. We also simulated the effects of CAM and CFT on growth and water conservation during drought using the Photo3 model. Within Clusia leaves, CAM and CFT are independent traits: CAM requires large palisade chlorenchyma cells, whereas hydrenchyma tissue governs interspecific differences in CFT . In addition, our model suggests that CAM supersedes CFT as a means to maximise CO2 assimilation and minimise transpiration during drought. Our study challenges the assumption that CAM and CFT are mutually dependent traits within succulent leaves.

Responses of photosystem to long-term light stress in a typically shade-tolerant species Panax notoginseng.

Photosynthetic adaptive strategies vary with the growth irradiance. The potential photosynthetic adaptive strategies of shade-tolerant species Panax notoginseng (Burkill) F. H. Chen to long-term high light and low light remains unclear. Photosynthetic performance, photosynthesis-related pigments, leaves anatomical characteristics and antioxidant enzyme activities were comparatively determined in P. notoginseng grown under different light regimes. The thickness of the upper epidermis, palisade tissue, and lower epidermis were declined with increasing growth irradiance. Low-light-grown leaves were declined in transpiration rate (Tr) and stomatal conductance (Cond), but intercellular CO2 concentration (C i) and net photosynthesis rate (P n) had opposite trends. The maximum photo-oxidation (P m) was greatly reduced in 29.8% full sunlight (FL) plants; The maximum quantum yield of photosystem II (F v/F m) in 0.2% FL plants was significantly lowest. Electron transport, thermal dissipation, and the effective quantum yield of PSI [Y(I)] and PSII [Y(II)] were declined in low-light-grown plants compared with high-light-grown P. notoginseng. The minimum value of non-regulated energy dissipation of PSII [Y(NO)] was recorded in 0.2% FL P. notoginseng. OJIP kinetic curve showed that relative variable fluorescence at J-phase (V J) and the ratio of variable fluorescent F K occupying the F J-F O amplitude (W k) were significantly increased in 0.2% FL plants. However, the increase in W k was lower than the increase in V J. In conclusion, PSI photoinhibition is the underlying sensitivity of the typically shade-tolerant species P. notoginseng to high light, and the photodamage to PSII acceptor side might cause the typically shade-tolerant plants to be unsuitable for long-term low light stress.

Morphoanatomical Changes in Eucalyptus grandis Leaves Associated with Resistance to Austropuccinia psidii in Plants of Two Ages.

The fungus Austropuccinia psidii infects young tissues of Eucalyptus plants until they are two years old in the nursery and field, causing Myrtaceae rust. The characteristics making older eucalypt leaves resistant to A. psidii and the reason for the low levels of this pathogen in older plants need evaluations. The aim of this study was to evaluate the morphological differences between Eucalyptus grandis leaves of different growth stages and two plant ages to propose a visual phenological scale to classify E. grandis leaves according to their maturation stages and to evaluate the time of leaf maturation for young and adult plants. A scale, based on a morphological differentiation for E. grandis leaves, was made. The color, shape and size distinguished the leaves of the first five leaf pairs. Anatomical analysis showed a higher percentage of reinforced tissue, such as sclerenchyma-like tissue and collenchyma, greater leaf blade thickness, absence of lower palisade parenchyma in the mature leaves and a higher number of cavities with essential oils than in younger ones. Changes in anatomical characteristics that could reduce the susceptibility of older E. grandis leaves to A. psidii coincide with the time of developing leaf resistance. Reduced infection of this pathogen in older plants appears to be associated with a more rapid maturation of their leaf tissues.

Steric Barrier‐Steered Reaction Sites in Micellar Catalysis

AbstractIn the pursuit of an advanced micellar catalysis system, the reaction sites in micelles determine its catalytic performances. However, the intrinsic polarity gradient of micelles anchors the reactants in the fixed regions, leading to an unmet challenge to steer the reaction sites to the optimal ones. To overcome this limitation, a Förster resonance energy transfer (FRET) spectroscopic ruler is established to position the true sites of reactants in micellar catalysis by using tetraphenylethylene (TPE) in the aggregation‐induced emission (AIE) micelles as the FRET donor and Nile red as the FRET acceptor. Subsequently, the customizable TPE steric barriers in the AIE micelles are apt to mediate the reactants into the polar micellar surface, the semipolar palisade layer, or the nonpolar internal layer, achieving the corresponding catalytic efficiencies. Additionally, the universality of steric barrier‐steered reaction sites in micellar catalysis is further demonstrated by the simple incorporation of small nonpolar molecules into the commercially available surfactants. To the authors’ knowledge, this is the first report on the design of steric barriers to steer the reaction sites in micellar catalysis. These findings open up attractive perspectives for the exploration of new classes of efficient micellar catalysis systems in a variety of reactions.

The Effects of Enhanced Ultraviolet-B Radiation on Leaf Photosynthesis and Submicroscopic Structures in Mangifera indica L. cv. ‘Tainong No 1’

Objective: In the future, the stress of enhanced UV-B radiation on the Earth will first affect the photosynthesis of plants, including mangoes. Therefore, it is necessary to study the effects of enhanced UV-B radiation on the photosynthesis of mangoes. Methods: ‘Tainong No 1’ mango trees in the field were selected as the experimental material and divided into 2 groups: one group was shined under 96 kJ·m−2·d−1 UV-B lamps for artificially simulated treatment of enhanced UV-B radiation, and the other group was shined under sunshine directly as the control (CK). The main photosynthetic physiological indicators were measured with conventional methods, and the expression levels of the genes encoding large and small subunits of the Rubisco enzyme were measured with fluorescent qPCR. The changes in stomatal morphology and chloroplast structure were observed with scanning electron microscopy and transmission electron microscopy. Results: The content of malondialdehyde (MDA) and the relative conductivity in the leaves of the treatment tended to be significantly higher than those of the CK. The net photosynthetic rate (Pn) of the treatment tended to decrease and be lower than that of CK. The dynamics of intercellular CO2 concentration (Ci) of the treatment and CK changed differently from each other but generally tended to decrease, and that of the treatment tended to be significantly higher than that of CK. The stomatal conductance (Gs) of the treatment and CK both generally decreased, and that of the treatment was always significantly lower than that of CK. The contents of chlorophyll a, chlorophyll b and total chlorophyll and the ratio of chlorophyll a/b of the treatment were lower than those of CK, while the carotenoid content showed the opposite trend. The stomata and the surface of leaves of the treatment were sunken and damaged, respectively. The palisade tissue, spongy tissue and upper epidermis thickened more, and the total thickness significantly increased. Meanwhile, the ratio of palisade tissue to spongy tissue decreased. During treatment, the chloroplasts were swollen and shortened, the number of chloroplasts was reduced, the starch grains were degraded, and the grana lamella were distorted, loosely arranged and blurred. The expression of the genes encoding the Rubisco large subunit (rbcL) in the treatment was significantly inhibited, while that encoding the Rubisco small subunit (rbcS) decreased first and increased later. In conclusion, 96 kJ·m−2·d−1 enhanced UV-B radiation treatment caused damage to the leaf cell membrane system. This led to stomatal limitation of photosynthesis by destroying the stomatal structure and nonstomatal limitation of photosynthesis by damaging the submicrostructure of the chloroplasts and downregulating the expression of rbcL. The leaves may resist the photosynthetic damage caused by enhanced UV-B radiation by upregulating rbcS expression as much as possible.

Detection of silver nanoparticles inside leaf of European beech (Fagus sylvatica L.)

In a greenhouse experiment, silver nanoparticles (Ag-NPs) were applied on European beech (Fagus sylvatica L.) leaves using the droplet application method. Scanning electron microscopy (SEM) analyses showed that after 24 h silver nanoparticles were mostly present in aggregates or as single particles on the surface of the leaf, surrounding or covering the stomata. Analyses of cross sections of the leaf revealed that some silver nanoparticles were adhering to the cell walls of the mesophyll and palisade cells, most likely after penetration into the leaf through the stomata as particles and not as Ag ions. Our preliminary results showed evidence of foliar uptake of silver nanoparticles in European beech. This opens new insights on the ability of trees to take up solid nanosized particles, eventually contained in raindrops, through their leaves, and potentially transport them to other parts of the tree. This study would be helpful for investigating the role of trees in atmospheric ultrafine particle mitigation.