RESUMO
BACKGROUND: This study was aimed to determine the taxonomic position and delimitation of fifteen Lamiaceae taxa using leaf epidermal morpho-anatomical features in Lahore. A main objective of the study was also the revision and upgradation of Lamiaceae taxa in the flora of Pakistan, as no details of studied species are found in the flora of Pakistan. METHODS: The examination of significant anatomical parameters, such as epidermal cell shape and size, stomatal types, guard and subsidiary cells shape and size, stomatal cavity size, trichome size and shape, oil droplets, crystals, and secretory cavity characteristics were studied using light microscopic (LM) and scanning electron microscopic (SEM) techniques. Among all the studied Lamiaceae species, these anatomical features varied significantly. Principal component analysis and correlation were done to distinguish the species' similarities. RESULTS: Most species had pentagonal and hexagonal epidermal cells with straight anticlinal wall thickness. On the adaxial surface, paracytic stomata were found in Ocimum basilicum L. and Rosmarinus officinalis L. Diacytic stomata was observed in Ajuga reptans L. and anisocytic stomata in Galeopsis tetrahit L. In the abaxial surface, trichomes were present in five species, i.e., Mentha suaveolens Ehrh. A. reptans, Thymus vulgaris L., M. haplocalyx, and Salvia splendens Ewat. In S. splendens, peltate and glandular trichomes were seen whereas, in other species, trichomes were long, unbranched glandular and had tapering ends. In adaxial side trichomes were present only in M. suaveolens, A. reptans, S. bazyntina, O. basciculum, S. splendens, S. officinalis, S. rosemarinus. In other species, trichomes were absent on the adaxial surface. In abaxial view, M. suaveolens had the largest length of trichomes, and O. basciculum had the smallest. S. splendens L. had the largest trichome width, while T. vulgaris had the smallest. CONCLUSION: Hence, according to these findings, morpho-anatomical traits are useful for identifying Lamiaceae taxa. Also, there is a need of upgradation and addition of studied taxa in flora of Pakistan comprehensively.
Assuntos
Lamiaceae , Folhas de Planta , Paquistão , Lamiaceae/anatomia & histologia , Lamiaceae/ultraestrutura , Folhas de Planta/anatomia & histologia , Folhas de Planta/ultraestrutura , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/ultraestrutura , Microscopia Eletrônica de Varredura , Tricomas/anatomia & histologia , Tricomas/ultraestrutura , Epiderme Vegetal/anatomia & histologia , Epiderme Vegetal/ultraestruturaRESUMO
Dwarf bamboo (Indocalamus decorus) is an O3-tolerant plant species. To identify the possible mechanism and response of leaf morphological, antioxidant, and anatomical characteristics to elevated atmospheric O3 (EO3) concentrations, we exposed three-year-old I. decorus seedlings to three O3 levels (low O3-LO: ambient air; medium O3-MO: Ambient air+70 ppb high O3-HO: Ambient air+140 ppb O3) over a growing season using open-top chambers. Leaf shape and stomatal characteristics, and leaf microscopic structure of I. decorus were examined. The results indicated that 1) the stomata O3 flux (Fst) of HO decreased more rapidly under EO3 as the exposure time increased. The foliar O3 injury of HO and MO occurred when AOT40 was 26.62 ppm h and 33.20 ppm h, respectively, 2) under EO3, leaf number, leaf mass per area, leaf area, and stomata length/width all decreased, while leaf thickness, stomatal density, width, and area increased compared to the control, 3) MDA and total soluble protein contents all showed significantly increase under HO (36.57% and 32.77%) and MO(31.91% and 19.52%) while proline contents only increased under HO(33.27%). 4) MO and HO increased bulliform cells numbers in the leaves by 6.28% and 23.01%, respectively. HO reduced the transverse area of bulliform cells by 13.73%, while MO treatments had no effect, and 5) the number of fusoid cells interspace, the transverse area of fusoid cells interspace, and mesophyll thickness of HO significantly increased by 11.16%, 28.58%, and 13.42%, respectively. In conclusion, I. decorus exhibits strong O3 tolerance characteristics, which stem from adaptions in the leaf's morphological, structural, antioxidant, and anatomical features. One critical attribute was the enlargement of the bulliform cell transverse area and the transverse area of fusoid cells interspace that drove this resistance to O3. Local bamboo species with high resistance to O3 pollution thus need to be promoted for sustained productivity and ecosystem services in areas with high O3 pollution.
Assuntos
Poluentes Atmosféricos , Ozônio , Folhas de Planta , Folhas de Planta/anatomia & histologia , Folhas de Planta/efeitos dos fármacos , Ozônio/toxicidade , Poluentes Atmosféricos/toxicidade , Poluentes Atmosféricos/análise , Poaceae/efeitos dos fármacos , Poaceae/anatomia & histologia , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/anatomia & histologiaRESUMO
This article describes detailed and novel data on the anatomy and histochemistry of leaves, stems, and roots of Camonea umbellata (L.) A.R.Simões & Staples in different environments for the identification of characters with taxonomical value and of ecological importance, with provision of light and scanning electron microscopy images. To analyze the characters, we collected samples of the vegetative organs of three individuals in each of three populations, which were in a grazing area, an urban environment, and a biological reserve. The main diagnostic anatomical markers for the identification of C. umbellata include amphistomatic leaves, tetracytic and brachyparatetracytic stomata, peltate trichomes, long simple trichomes, epidermis with striated cuticle ornamentation, mesophyll with acute borders, presence of druses, secretory channels, angular collenchyma, fibrous pericycle in the stem, intraxylary phloem in the vegetative organs, oil bodies throughout the midrib, petiole, stem and root, and epicuticular waxes of the crust and coiled rodlet types. Since the characters above did not show variation in the environments evaluated, we consider these characters taxonomically useful for the identification of C. umbellata. RESEARCH HIGHLIGHTS: The anatomy of the aerial vegetative organs of Camonnea umbellata retains common Convolvulaceae characters. The sinuosity of the epidermal cell walls and the density of trichomes in the epidermis of the petiole were visually variable characters among the analyzed individuals. Amphistomatic leaves, tetracytic and brachyparatetracytic stomata, peltate trichomes, epidermis with striated cuticle ornamentation, dorsiventral mesophyll with border acute, presence of druses, secretory structures, angular collenchyma, fibrous pericycle in the stem, intraxillary phloem, presence of oil bodies in all organs, and epicuticular waxes of the crust type and coiled rods were considered important anatomical markers for the recognition and correct identification of Camonea umbellata.
Assuntos
Microscopia Eletrônica de Varredura , Microscopia , Folhas de Planta , Raízes de Plantas , Caules de Planta , Tricomas , Folhas de Planta/anatomia & histologia , Folhas de Planta/ultraestrutura , Caules de Planta/anatomia & histologia , Caules de Planta/ultraestrutura , Tricomas/ultraestrutura , Tricomas/anatomia & histologia , Raízes de Plantas/anatomia & histologia , Raízes de Plantas/ultraestrutura , Estômatos de Plantas/ultraestrutura , Estômatos de Plantas/anatomia & histologia , Epiderme Vegetal/ultraestrutura , Epiderme Vegetal/anatomia & histologiaRESUMO
This research is to examine the macromorphological and foliar epidermal anatomical features of Lilium rosthornii Diels and its ability to plastically adapt to environmental forces, which is crucial for its taxonomic classification. L. rosthornii has macromorphological characteristics such as linear to lanceolate leaves of up to 20 cm in length and 2-3 cm in breadth, grouped in a whorled pattern. The blooms are voluminous and conspicuous, measuring up to 15 cm in diameter and are supported by a towering stalk that grows up to 1 m in height. The foliar epidermal structure of L. rosthornii exhibits a stomatal length of 82.02 ± 5.77 µm and a width of 29.19 ± 1.39 µm. These measurements suggest that the plant's stomata are influenced by its ploidy levels and may serve as adaptive mechanisms to enhance water consumption efficiency. The leaf structure shows a significant thickness of 398.74 ± 97.96 µm, which might potentially contribute to its ability to withstand environmental challenges. Additionally, the presence of defensive adaptations in the top and lower epidermal layers further supports this observation. The palisade tissue measurement (58.87 ± 9.56 m) and spongy tissue measurement (32.42 ± 12.72 µm) indicate a potential for photosynthetic optimization. Furthermore, there is a possible correlation between the vascular bundle width (28.15 ± 6.52 °m) and the efficiency of nutrition delivery. The results of this study emphasize the notable diversity in the foliar structures of L. rosthornii, offering valuable understanding of its morphological adaptations that have ecological and taxonomic significance. The findings provide a deeper comprehension of the potential impact of anatomical characteristics on plant function and categorization, hence providing significant insights to the domain of plant morphology and systematics. RESEARCH HIGHLIGHTS: Examines Lilium rosthornii's anatomical features and environmental adaptability for taxonomic relevance. Leaf thickness and epidermal defenses indicate resilience to environmental stress. Highlights the diversity in L. rosthornii's foliar structures, with implications for ecological and taxonomic significance Offers insights into the impact of anatomical characteristics on plant function and classification.
Assuntos
Lilium , Epiderme Vegetal , Folhas de Planta , Estômatos de Plantas , Folhas de Planta/anatomia & histologia , Lilium/anatomia & histologia , Epiderme Vegetal/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , Adaptação FisiológicaRESUMO
In the Mediterranean region, a reduction of annual precipitation and a longer and drier summer season are expected with climate change by the end of the century, eventually endangering forest survival. To cope with such rapid changes, trees may modulate their morpho-anatomical and physiological traits. In the present study, we focused on the variation in leaf gas exchange and different leaf morpho-anatomical functional traits of Quercus pubescens Willd. in summer using a long-term drought experiment in natura consisting of a dynamic rainfall exclusion system where trees have been submitted to amplified drought (AD) (~-30% of annual precipitation) since April 2012 and compared them with trees under natural drought (ND) in a Mediterranean forest. During the study, we analyzed net CO2 assimilation (An), stomatal conductance (gs), transpiration (E), water-use efficiency (WUE), stomatal size and density, density of glandular trichomes and non-glandular trichomes, thickness of the different leaf tissues, specific leaf area and leaf surface. Under AD, tree functioning was slightly impacted, since only An exhibited a 49% drop, while gs, E and WUE remained stable. The decrease in An under AD was regulated by concomitant lower stomatal density and reduced leaf thickness. Trees under AD also featured leaves with a higher non-glandular trichome density and a lower glandular trichome density compared with ND, which simultaneously limits transpiration and production costs. This study points out that Q. pubescens exhibits adjustments of leaf morpho-anatomical traits which can help trees to acclimate to AD scenarios as those expected in the future in the Mediterranean region.
Assuntos
Secas , Florestas , Folhas de Planta , Quercus , Quercus/fisiologia , Quercus/anatomia & histologia , Folhas de Planta/fisiologia , Folhas de Planta/anatomia & histologia , Chuva , Transpiração Vegetal/fisiologia , Árvores/fisiologia , Árvores/anatomia & histologia , Mudança Climática , Estômatos de Plantas/fisiologia , Estômatos de Plantas/anatomia & histologiaRESUMO
Shading is an environmental factor that has been little investigated regarding its effects on emergent aquatic plants. Typha domingensis Pers. is an emergent macrophyte that demonstrates some plasticity for self-shading, and as it can shade other species in the same area, the effect of shading on its traits deserves further investigation. The objective of the present study was to evaluate the gas exchange, leaf anatomy, and growth of T. domingensis cultivated under increasing shading intensities. The plants were collected and propagated in a greenhouse, and the clones were subjected to four shading intensities: 0% (unshaded), 35%, 73%, and 83% shading created by black nets. Growth traits, clonal production, photosynthesis, transpiration, and leaf anatomy were evaluated. The 73% and 83% shading promoted the death of all plants, but all plants survived in the 35% and unshaded treatments. Compared with the unshaded treatment, the 35% shading treatment promoted a higher photosynthetic rate and greater transpiration, supporting increased growth and production of clones. The increase in the photosynthetic rate in the 35% shading was related to the increase in leaf area which increased the photosynthesis of the whole plant. The 73% and 83% treatments inhibited the development of photosynthetic parenchyma and stomata in T. domingensis, leading to a drastic reduction in photosynthesis and energy depletion. Therefore, T. domingensis does not tolerate intense shading, but its photosynthetic characteristics and growth are favored by mild shading, a factor that may be of great importance for its competitiveness and invasive behavior.
Assuntos
Fotossíntese , Folhas de Planta , Typhaceae , Fotossíntese/fisiologia , Folhas de Planta/fisiologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/efeitos da radiação , Folhas de Planta/crescimento & desenvolvimento , Typhaceae/fisiologia , Transpiração Vegetal/fisiologia , Luz Solar , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Estômatos de Plantas/anatomia & histologiaRESUMO
The classification and identification of Aster glehnii F. Schmidt are determined from its foliar epidermal anatomical features. Scanning electronic microscopy has been used to determine the foliar epidermal anatomical characteristics of the species in detail. This study compared the qualitative and quantitative characteristics of the leaf epidermis of A. glehnii for taxonomic identification to be used as a reference for future studies on the species. A. glehnii has smooth, thin cuticles, depressed anomocytic stomata dispersed randomly throughout the leaf surface, polygonal epidermal cells with straight to slightly curved anticlinal walls, and no trichomes. There are obvious veins containing thick-walled bundle sheath cells. The stomatal density is between 100 and 150 stomata per millimeter. The vein density ranges from five to 10 veins per millimeter, and the epidermal cells are 10 to 20 µm long and 5 to 10 µm in width. Understanding the connections between the different A. glehnii species and categorizing and identifying them depend heavily on these foliar epidermal structural features. Taxonomy and conservation are closely intertwined because the former serves as the basis for comprehending and safeguarding biodiversity. RESEARCH HIGHLIGHTS: Optical microscopy of the A. glehnii leaf epidermis for taxonomic identification SEM was used to identify and authenticate endemic species Microscopic identification of endemic species can assist in the conservation.
Assuntos
Microscopia Eletrônica de Varredura , Epiderme Vegetal , Folhas de Planta , Estômatos de Plantas , Folhas de Planta/anatomia & histologia , Folhas de Planta/ultraestrutura , Folhas de Planta/citologia , Epiderme Vegetal/ultraestrutura , Epiderme Vegetal/anatomia & histologia , Epiderme Vegetal/citologia , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/ultraestrutura , Asteraceae/anatomia & histologia , Asteraceae/citologia , Asteraceae/classificação , Asteraceae/ultraestruturaRESUMO
AbstractQuantifying the relative contribution of functional and developmental constraints on phenotypic variation is a long-standing goal of macroevolution, but it is often difficult to distinguish different types of constraints. Alternatively, selection can limit phenotypic (co)variation if some trait combinations are generally maladaptive. The anatomy of leaves with stomata on both surfaces (amphistomatous) present a unique opportunity to test the importance of functional and developmental constraints on phenotypic evolution. The key insight is that stomata on each leaf surface encounter the same functional and developmental constraints but potentially different selective pressures because of leaf asymmetry in light capture, gas exchange, and other features. Independent evolution of stomatal traits on each surface imply that functional and developmental constraints alone likely do not explain trait covariance. Packing limits on how many stomata can fit into a finite epidermis and cell size-mediated developmental integration are hypothesized to constrain variation in stomatal anatomy. The simple geometry of the planar leaf surface and knowledge of stomatal development make it possible to derive equations for phenotypic (co)variance caused by these constraints and compare them with data. We analyzed evolutionary covariance between stomatal density and length in amphistomatous leaves from 236 phylogenetically independent contrasts using a robust Bayesian model. Stomatal anatomy on each surface diverges partially independently, meaning that packing limits and developmental integration are not sufficient to explain phenotypic (co)variation. Hence, (co)variation in ecologically important traits like stomata arises in part because there is a limited range of evolutionary optima. We show how it is possible to evaluate the contribution of different constraints by deriving expected patterns of (co)variance and testing them using similar but separate tissues, organs, or sexes.
Assuntos
Magnoliopsida , Estômatos de Plantas , Estômatos de Plantas/anatomia & histologia , Magnoliopsida/anatomia & histologia , Teorema de Bayes , Folhas de Planta/anatomia & histologia , FenótipoRESUMO
Sustaining crop productivity and resilience in water-limited environments and under rising temperatures are matters of concern worldwide. We investigated the leaf anatomical traits that underpin our recently identified link between leaf width (LW) and intrinsic water use efficiency (iWUE), as traits of interest in plant breeding. Ten sorghum lines with varying LW were grown under three temperatures to expand the range of variation of both LW and gas exchange rates. Leaf gas exchange, surface morphology and cross-sectional anatomy were measured and analysed using structural equations modelling. Narrower leaves had lower stomatal conductance (gs ) and higher iWUE across growth temperatures. They also had smaller intercellular airspaces, stomatal size, percentage of open stomatal aperture relative to maximum, hydraulic pathway, mesophyll thickness, and leaf mass per area. Structural modelling revealed a developmental association among leaf anatomical traits that underpinned gs variation in sorghum. Growing temperature and LW both impacted leaf gas exchange rates, but only LW directly impacted leaf anatomy. Wider leaves may be more productive under well-watered conditions, but consume more water for growth and development, which is detrimental under water stress.
Assuntos
Estômatos de Plantas , Sorghum , Temperatura , Estômatos de Plantas/anatomia & histologia , Fotossíntese , Folhas de Planta/anatomia & histologiaRESUMO
The genus Iris L., comprising approximately 210 species, is one of the most species-rich genera in the family Iridaceae. In this study, the first comprehensive leaf micromorphological characters of Korean irises were studied using light and scanning electron microscopy. Our objective was to evaluate the foliar micromorphological characteristics (namely epidermal cells, stomata types, and guard cell size) of Korean Iris taxa in a systematic context. All the investigated Korean Iris taxa had amphistomatic or hypostomatic leaves with anomocytic stomatal complexes. Guard cell length varied among species, ranging from 24.8 µm (I. rossii) to 56.0 µm (I. domestica). Although the presence of papillae on the outer periclinal wall is not of taxonomic significance, leaf margin pattern, guard cell size, and sunken stomata type were useful for species-level identification of Korean Iris species. The occurrence of polymorphic stomatal types was reported here for the first time, and the correlation between genome size and epidermal guard cell length was discussed.
Assuntos
Epiderme Vegetal , Estômatos de Plantas , Microscopia Eletrônica de Varredura , Epiderme Vegetal/anatomia & histologia , Folhas de Planta/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , República da CoreiaRESUMO
The commonly observed negative relationship between stomatal density (SD) and atmospheric CO2 has led to SD being proposed as an indicator of atmospheric CO2 concentration. The use of SD as a proxy for CO2 , however, has been hampered by an insufficient understanding of the intraspecific variation of this trait. We hypothesized that SD in Pinus sylvestris, a widely distributed conifer, varies geographically and that this variation is determined by major climatic variables. By sampling needles from naturally growing trees along a latitudinal range of 32.25°, equivalent to 13.7°C gradient of mean annual temperature (MAT) across Europe, we found that SD decreased from the warmest southern sites to the coldest sites in the north at a rate of 4 stomata per mm2 for each 1°C, with MAT explaining 44% of the variation. Additionally, samples from a provenance trial exhibited a positive relationship between SD and the MAT of the original localities, suggesting that high SD is an adaptation to warm temperature. Our study revealed one of the strongest intraspecific relationships between SD and climate in any woody species, supporting the utility of SD as a temperature, rather than direct CO2 , proxy. In addition, our results predict the response of SD to climate warming.
Assuntos
Dióxido de Carbono , Pinus sylvestris/fisiologia , Estômatos de Plantas/fisiologia , Adaptação Fisiológica , Clima , Europa (Continente) , Pinus sylvestris/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , TemperaturaRESUMO
Stomata are essential pores flanked by guard cells that control gas exchange in plants. We can utilize stomatal size and density measurements as a proxy for a plant's capacity for gas exchange. While stomatal responses to stressful environments are well studied; data are lacking in the responses across mutant genotypes of the same species in these trait and treatment interactions or genetic variation in phenotypic plasticity. We evaluated the effects of soil nutrient variation on macroscopic and stomatal traits of Arabidopsis thaliana T-DNA insertion mutants for which prior performance in a single benign growing condition were available. Nutrient-induced stress significantly impacted traits including plant biomass, height, fruit number, and leaf number which we denote as macroscopic traits. We found evidence that genotype by environment effects exist for macroscopic traits, yet total stomatal area variation, or "microscopic variation" across environments was modest. Divergence from the wildtype line varied by mutant background and these responses were variable among traits. These findings suggest that Arabidopsis employs a strategy of physiological compensation, sacrificing morphological traits to maintain stomatal production.
Assuntos
Arabidopsis/anatomia & histologia , Arabidopsis/genética , Mutação , Nutrientes , Estômatos de Plantas/anatomia & histologia , Solo/químicaRESUMO
Plant stomata are essential structures (pores) that control the exchange of gases between plant leaves and the atmosphere, and also they influence plant adaptation to climate through photosynthesis and transpiration stream. Many works in literature aim for a better understanding of these structures and their role in the evolution process and the behavior of plants. Although stomata studies in dicots species have advanced considerably in the past years, even there is not much knowledge about the stomata of cereal grasses. Due to the high morphological variation of stomata traits intra- and inter-species, detecting and classifying stomata automatically becomes challenging. For this reason, in this work, we propose a new system for automatic stomata classification and detection in microscope images for maize cultivars based on transfer learning strategy of different deep convolution neural netwoks (DCNN). Our performed experiments show that our system achieves an approximated accuracy of 97.1% in identifying stomata regions using classifiers based on deep learning features, which figures out as a nearly perfect classification system. As the stomata are responsible for several plant functionalities, this work represents an important advance for maize research, providing an accurate system in replacing the current manual task of categorizing these pores on microscope images. Furthermore, this system can also be a reference for studies using images from different cereal grasses.
Assuntos
Processamento de Imagem Assistida por Computador/métodos , Microscopia/métodos , Fotossíntese , Fenômenos Fisiológicos Vegetais , Estômatos de Plantas/classificação , Transpiração Vegetal , Zea mays/fisiologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/fisiologia , Zea mays/anatomia & histologiaRESUMO
Controlling the distribution of stomata is crucial for the adaptation of plants to new, or changing environments. While many plant species produce stomata predominantly on the abaxial leaf surface (hypostomy), some produce stomata on both surfaces (amphistomy), and the remaining few produce them only on the adaxial surface (hyperstomy). Various selective pressures have driven the evolution of these three modes of stomatal distribution. Despite recent advances in our understanding of stomatal development and dorsiventral leaf polarity, the genetic basis for the evolution of different stomatal distributions is still unclear. Here, we propose the genus Callitriche as a new model system to investigate patterns in the evolution of stomatal distribution. Callitriche comprises species with diverse lifestyles, including terrestrial, amphibious, and obligately aquatic plants. We found that species in this genus cover all three modes of dorsiventral stomatal distribution, making it a desirable model for comparative and evolutionary analyses on distribution modes. We further characterized the genetic basis of the different distribution modes, focusing on the stomatal key transcription factor SPEECHLESS. Future research using the promising model system Callitriche would open a new direction for evolutionary developmental biology studies on stomata.
Assuntos
Evolução Biológica , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/crescimento & desenvolvimento , Estômatos de Plantas/genética , Plantaginaceae/anatomia & histologia , Plantaginaceae/crescimento & desenvolvimento , Plantaginaceae/genética , Regulação da Expressão Gênica de Plantas , Genes de PlantasRESUMO
The combined response of exclusion of solar ultraviolet radiation (UV-A+B and UV-B) and static magnetic field (SMF) pre-treatment of 200 mT for 1 h were studied on soybean (Glycine max) leaves using synchrotron imaging. The seeds of soybean with and without SMF pre-treatment were sown in nursery bags kept in iron meshes where UV-A+B (280-400 nm) and UV-B (280-315 nm) from solar radiation were filtered through a polyester filters. Two controls were planned, one with polythene filter controls (FC)- which allows all the UV (280-400 nm); the other control had no filter used (open control-OC). Midrib regions of the intact third trifoliate leaves were imaged using the phase-contrast imaging technique at BL-4, Indus-2 synchrotron radiation source. The solar UV exclusion results suggest that ambient UV caused a reduction in leaf growth which ultimately reduced the photosynthesis in soybean seedlings, while SMF treatment caused enhancement of leaf growth along with photosynthesis even under the presence of ambient UV-B stress. The width of midrib and second-order veins, length of the second-order veins, leaf vein density, and the density of third-order veins obtained from the quantitative image analysis showed an enhancement in the leaves of plants that emerged from SMF pre-treated seeds as compared to untreated ones grown in open control and filter control conditions (in the presence of ambient UV stress). SMF pre-treated seeds along with UV-A+B and UV-B exclusion also showed significant enhancements in leaf parameters as compared to the UV excluded untreated leaves. Our results suggested that SMF-pretreatment of seeds diminishes the ambient UV-induced adverse effects on soybean.
Assuntos
Glycine max/efeitos da radiação , Campos Magnéticos , Folhas de Planta/efeitos da radiação , Síncrotrons , Raios Ultravioleta , Folhas de Planta/anatomia & histologia , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Feixe Vascular de Plantas/anatomia & histologia , Feixe Vascular de Plantas/efeitos da radiação , Espectrofotometria UltravioletaRESUMO
The leaf intercellular airspace is a tortuous environment consisting of cells of different shapes, packing densities, and orientation, all of which have an effect on the travelling distance of molecules from the stomata to the mesophyll cell surfaces. Tortuosity, the increase in displacement over the actual distance between two points, is typically defined as encompassing the whole leaf airspace, but heterogeneity in pore dimensions and orientation between the spongy and palisade mesophyll likely result in heterogeneity in tortuosity along different axes and would predict longer traveling distance along the path of least tortuosity, such as vertically within the columnar cell matrix of the palisade layer. Here, we compare a previously established geometric method to a random walk approach, novel for this analysis in plant leaves, in four different Eucalyptus species. The random walk method allowed us to quantify directional tortuosity across the whole leaf profile, and separately for the spongy and palisade mesophyll. For all species tortuosity was higher in the palisade mesophyll than the spongy mesophyll and horizontal (parallel to the epidermis) tortuosity was consistently higher than vertical (from epidermis to epidermis) tortuosity. We demonstrate that a random walk approach improves on previous geometric approaches and is valuable for investigating CO2 and H2 O transport within leaves.
Assuntos
Eucalyptus/anatomia & histologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/citologia , Ar , Isótopos de Carbono/análise , Parede Celular/ultraestrutura , Eucalyptus/ultraestrutura , Imageamento Tridimensional , Células do Mesofilo/química , Microscopia Eletrônica de Varredura , Células Vegetais , Folhas de Planta/ultraestrutura , Estômatos de Plantas/anatomia & histologiaRESUMO
1',4'-trans-diol-ABA is a key precursor of the biosynthesis of abscisic acid (ABA) biosynthesis in fungi. We successfully obtained the pure compound from a mutant of Botrytis cinerea and explored its function and possible mechanism on plants by spraying 2 mg/L 1',4'-trans-diol-ABA on tobacco leaves. Our results showed that this compound enhanced the drought tolerance of tobacco seedlings. A comparative transcriptome analysis showed that a large number of genes responded to the compound, exhibiting 1523 genes that were differentially expressed at 12 h, which increased to 1993 at 24 h and 3074 at 48 h, respectively. The enrichment analysis demonstrated that the differentially expressed genes (DEGs) were primarily enriched in pathways related to hormones and resistance. The DEGs of transcription factors were generally up-regulated and included the bHLH, bZIP, ERF, MYB, NAC, WRKY and HSF families. Moreover, the levels of expression of PYL/PYR, PP2C, SnRK2, and ABF at the ABA signaling pathway responded positively to exogenous 1',4'-trans-diol-ABA. Among them, seven ABF transcripts that were detected were significantly up-regulated. In addition, the genes involved in salicylic acid, ethylene and jasmonic acid pathways, reactive oxygen species scavenging system, and other resistance related genes were primarily induced by 1',4'-trans-diol-ABA. These findings indicated that treatment with 1',4'-trans-diol-ABA could improve tolerance to plant abiotic stress and potential biotic resistance by regulating gene expression, similar to the effects of exogenous ABA.
Assuntos
Ácido Abscísico/análogos & derivados , Nicotiana/efeitos dos fármacos , Nicotiana/genética , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Ácido Abscísico/farmacologia , Botrytis/química , Secas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ontologia Genética , Redes Reguladoras de Genes , Genes de Plantas , Modelos Biológicos , Reguladores de Crescimento de Plantas/genética , Proteínas de Plantas/genética , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/fisiologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Nicotiana/fisiologia , Fatores de Transcrição/genéticaRESUMO
Opportunistic diversification has allowed ferns to radiate into epiphytic niches in angiosperm dominated landscapes. However, our understanding of how ecophysiological function allowed establishment in the canopy and the potential transitionary role of the hemi-epiphytic life form remain unclear. Here, we surveyed 39 fern species in Costa Rican tropical forests to explore epiphytic trait divergence in a phylogenetic context. We examined leaf responses to water deficits in terrestrial, hemi-epiphytic and epiphytic ferns and related these findings to functional traits that regulate leaf water status. Epiphytic ferns had reduced xylem area (-63%), shorter stipe lengths (-56%), thicker laminae (+41%) and reduced stomatal density (-46%) compared to terrestrial ferns. Epiphytic ferns exhibited similar turgor loss points, higher osmotic potential at saturation and lower tissue capacitance after turgor loss than terrestrial ferns. Overall, hemi-epiphytic ferns exhibited traits that share characteristics of both terrestrial and epiphytic species. Our findings clearly demonstrate the prevalence of water conservatism in both epiphytic and hemi-epiphytic ferns, via selection for anatomical and structural traits that avoid leaf water stress. Even with likely evolutionarily constrained physiological function, adaptations for drought avoidance have allowed epiphytic ferns to successfully endure the stresses of the canopy habitat.
Assuntos
Gleiquênias/fisiologia , Folhas de Planta/fisiologia , Evolução Biológica , Costa Rica , Secas , Folhas de Planta/química , Estômatos de Plantas/anatomia & histologia , Estômatos de Plantas/fisiologia , Pressão , ÁguaRESUMO
Abscisic acid (ABA) can induce rapid stomatal closure in seed plants, but the action of this hormone on the stomata of fern and lycophyte species remains equivocal. Here, ABA-induced stomatal closure, signaling components, guard cell K+ and Ca2+ fluxes, vacuolar and actin cytoskeleton dynamics, and the permeability coefficient of guard cell protoplasts (Pf) were analyzed in species spanning the diversity of vascular land plants including 11 seed plants, 6 ferns, and 1 lycophyte. We found that all 11 seed plants exhibited ABA-induced stomatal closure, but the fern and lycophyte species did not. ABA-induced hydrogen peroxide elevation was observed in all species, but the signaling pathway downstream of nitric oxide production, including ion channel activation, was only observed in seed plants. In the angiosperm faba bean (Vicia faba), ABA application caused large vacuolar compartments to disaggregate, actin filaments to disintegrate into short fragments and Pf to increase. None of these changes was observed in the guard cells of the fern Matteuccia struthiopteris and lycophyte Selaginella moellendorffii treated with ABA, but a hypertonic osmotic solution did induce stomatal closure in fern and the lycophyte. Our results suggest that there is a major difference in the regulation of stomata between the fern and lycophyte plants and the seed plants. Importantly, these findings have uncovered the physiological and biophysical mechanisms that may have been responsible for the evolution of a stomatal response to ABA in the earliest seed plants.