Leaf Parenchyma Research Articles

Host Recognition for Survival of Plant Pathogens

The intact, healthy plant is a community of cells built in a fortress-like fashion. Plant cells consist of cell wall contains the nucleus and various organelles and all the substances for which the pathogens attack them. The cytoplasm and the organelles it contains are separated from each other by membranes that carry various types of proteins embedded in them (Fig. 5-2). The plant surfaces that come in contact with the environment either consist of cellulose, as in the epidermal cells of roots and in the intercellular spaces of leaf parenchyma cells, or consist of a cuticle that covers the epidermal cell walls, as is the case in the aerial parts of plants. Often an additional layer, consisting of waxes, is deposited outside the cuticle, especially on younger parts of plants Pathogens attack plants because during their evolutionary development they have acquired the ability to live off the substances manufactured by the host plants, and some of the pathogens depend on these substances for survival. Many substances are contained in the protoplast of the plant cells, however, and if pathogens are to gain access to them they must first penetrate the outer barriers formed by the cuticle and/or cell walls. Even after the outer cell wall has been penetrated, further invasion of the plant by the pathogen necessitates the penetration of more cell walls. Furthermore, the plant cell contents are not always found in forms immediately utilizable by the pathogen and must be broken down to units that the pathogen can absorb and assimilate. Moreover, the plant, reacting to the presence and activities of the pathogen, produces structures and chemical substances that interfere with the advance or the existence of the pathogen; if the pathogen is to survive and to continue living off the plant, it must be able to overcome such obstacles. Therefore, for a pathogen to infect a plant it must be able to make its way into and through the plant, obtain nutrients from the plant, and neutral

Metabolite profiling and histochemical localization of alkaloids in Hippeastrum papilio (Ravena) van Scheepen

Hippeastrum papilio (Amaryllidaceae) is a promising new source of galanthamine - an alkaloid used for the cognitive treatment of Alzheimer's disease. The biosynthesis and accumulation of alkaloids are tissue - and organ-specific. In the present study, histochemical localization of alkaloids in H. papilio's plant organs with Dragendorff's reagent, revealed their presence in all studied samples. Alkaloids were observed in vascular bundles, vacuoles, and intracellular spaces, while in other plant tissues and structures depended on the plant organ. The leaf parenchyma and the vascular bundles were indicated as alkaloid-rich structures which together with the high proportion of alkaloids in the phloem sap (49.3% of the Total Ion Current – TIC, measured by GC-MS) indicates the green tissues as a possible site of galanthamine biosynthesis. The bulbs and roots showed higher alkaloid content compared to the leaf parts. The highest alkaloid content was found in the inner bulb part. GC-MS metabolite profiling of H. papilio's root, bulb, and leaves revealed about 82 metabolites (>0.01% of TIC) in the apolar, polar, and phenolic acid fractions, including organic acids, fatty acids, sterols, sugars, amino acids, free phenolic acids, and conjugated phenolic acids. The most of organic and fatty acids were in the peak part of the root, while the outermost leaf was enriched with sterols. The outer and middle parts of the bulb had the highest amount of saccharides, while the peak part of the middle leaf had most of the amino acids, free and conjugated phenolic acids.

Overexpression of OsSnRK1a through a green tissue-specific promoter improves rice yield by accelerating sheath-to-panicle transport of nonstructural carbohydrates and increasing leaf photosynthesis

The redistribution of nonstructural carbohydrates (NSCs) in rice (Oryza sativa) sheaths contributes greatly to grain filling. Sucrose nonfermenting-1-related protein kinase 1 (SnRK1) regulates sheath-to-panicle transport of NSCs during rice grain filling; however, it is unknown whether elevated activity of SnRK1 in sheaths improves NSC transport and grain filling. Expression of OsSnRK1a is mainly responsible for regulating SnRK1 activity in rice sheaths. Analysis of transgenic rice plants containing the OsSnRK1a promoter::GUS construct indicated that OsSnRK1a is widely expressed in rice. Notably, OsSnRK1a is highly expressed in mesophyll cells of sheaths. Therefore, a green tissue promoter specifically expressed in sheaths and leaf parenchyma cells and phloem tissue was used to over-express OsSnRK1a in japonica rice. The transgenic lines exhibited increased SnRK1a expression and SnRK1 activity in sheaths. The NSC and starch in the transgenic lines and WT all showed accumulation before heading and during the early-filling stage, and declining at the peak filling stage. But the starch and NSC content in transgenic lines was lower than that of WT. Moreover, the transgenic lines showed lower sucrose contents and higher sucrose efflux rates. The accelerated sheath NSC transport improved grain filling, and stimulated panicle development in transgenic lines. SnRK1a expression and SnRK1 activity were also increased in the leaves of transgenic lines, which improved leaf photosynthetic activity and contributed to optimal grain filling and panicle development. These results verify the promotion of high SnRK1 activity in sheath NSC transport, and also provide a new approach to improving sheath NSC transport and rice yield.

Identification of a Cucumber Mosaic Virus from Cucurbita pepo on New Reclamation Land in Egypt and the Changes Induced in Pumpkin Plants

In 2020, the leaves and fruit of 50 pumpkin plants with suspected cucumber mosaic virus (CMV) symptoms of leaf mosaic, vein yellowing, and mild leaf curling were collected from Sharq El-Owainat (Al Wadi El-Gaded governorate), a new reclamation land in Egypt. This study was aimed at deciphering and characterizing the causal agent of the leaf yellowing disease associated with pumpkin plants in Egypt. The causal agent was identified by serological, cytological, and molecular means. The serological identification by DAS–ELISA confirmed the presence of CMV in 20% of the plants. The cytological identification by electron microscopy revealed typical cucumovirus isometric particles of 28–30 nm diameter in the cytoplasm of the leaf parenchyma, epidermal cells, the integument, and the nucleus. Molecular characterization by one-step reverse transcriptase-PCR yielded the required size of amplicon (678 bp) for CMV. Additionally, mechanical sap inoculation was used to determine the host range and symptomatology of the isolated CMV in seventeen different plant species belonging to six different plant families. CMV replicated, moved systemically, and induced a range of symptoms in sixteen plant species. The isolated CMV was transmitted to pumpkin plants at a 16.4% rate by seeds. CMV-infected pumpkin plant leaves were characterized by a substantially low concentration of photosynthetic pigments, a high level of reducing sugars, relatively low protein levels, and a significant increase in total phenol contents, implying their potential role as antiviral agents. Ultrathin sections of infected cells revealed histological changes and cytological abnormalities in comparison to healthy plants. This is the first identification of CMV on new reclamation land in Egypt, pinpointing its swift spread, which could pose a major constraint to pumpkin production in Egypt.

Indirect organogenesis for high frequency shoot regeneration of two cultivars of Sansevieria trifasciata Prain differing in fiber production

Sansevieria trifasciata is used as an indoor plant, in traditional medicine and as a fiber source. Here we characterized fibers of two of varieties of S. trifasciata, Lorentii and Hahnii, and report a protocol for their propagation based on indirect shoot organogenesis. Structural and ribbon fibers were scattered within leaf parenchyma when viewed with confocal laser scanning microscopy. Chemical analysis of the fibers by mass spectrometry and high-performance chromatography revealed higher contents of cellulose and xylose in Lorentii than in Hahnii and significant differences for total lignin between both. A protocol for de novo shoot production was then developed using leaf explants. Time-course histological analyses showed that the first events of transdifferentiation were triggered preferentially in cells surrounding fibers and vascular bundles. Callogenesis and shoot performances were quantified for both varieties, and 2,4-D at 2 and 3 mg·L-1 yielded the best results for primary calli induction and fresh calli mass. The length, number, and mass of shoots produced did not differ significantly between the two cultivars. The fast morphogenic response of S. trifasciata to in vitro culture may be useful for mass propagation or other biotechnological purposes such as metabolite production.

Agromyzidae (Insecta: Diptera) species as an important agricultural pest

The Agromyzidae family represent a very particular group of phytophagous insects because of their habit. The larvae of this group of insects, when feeding on the plant, build galleries in the leaf parenchyma that also provide them with shelter. Although most representatives of this group of insects are leaf miners (around 75%), there are agromyzid larvae that can feed on roots, stems, pods and inflorescences of herbaceous plants, and trunks and branches of trees. The aim of this manuscript was to carry out an inventory of the Agromyzidae Family (Insecta: Diptera) related to its biogeography, bioecology, habitat, geographic distribution, taxonomy, life cycle, phenology and taxonomic and conceptual aspects of the Family, Subfamilies and Species. To this end, a bibliographic survey of Agromyzidae was carried out in the years 1937 to 2021. Only complete articles published in scientific journals and expanded abstracts presented at national and international scientific events, Doctoral Thesis and Master's Dissertation were considered. Data were also obtained from platforms such as: Academia.edu, Frontiers, Qeios, Pubmed, Biological Abstract, Publons, Dialnet, World, Wide Science, Springer, RefSeek, Microsoft Academic, Science and ERIC.

Chromosome Number, Ploidy Level, and Nuclear DNA Content in 23 Species of Echeveria (Crassulaceae)

Echeveria is a polyploid genus with a wide diversity of species and morphologies. The number of species registered for Echeveria is approximately 170; many of them are native to Mexico. This genus is of special interest in cytogenetic research because it has a variety of chromosome numbers and ploidy levels. Additionally, there are no studies concerning nuclear DNA content and the extent of endopolyploidy. This work aims to investigate the cytogenetic characteristics of 23 species of Echeveria collected in 9 states of Mexico, analyzing 2n chromosome numbers, ploidy level, nuclear DNA content, and endopolyploidy levels. Chromosome numbers were obtained from root tips. DNA content was obtained from the leaf parenchyma, which was processed according to the two-step protocol with Otto solutions and propidium iodide as fluorochrome, and then analyzed by flow cytometry. From the 23 species of Echeveria analyzed, 16 species lacked previous reports of 2n chromosome numbers. The 2n chromosome numbers found and analyzed in this research for Echeveria species ranged from 24 to 270. The range of 2C nuclear DNA amounts ranged from 1.26 pg in E. catorce to 7.70 pg in E. roseiflora, while the 1C values were 616 Mbp and 753 Mbp, respectively, for the same species. However, differences in the level of endopolyploidy nuclei were found, corresponding to 4 endocycles (8C, 16C, 32C and 64C) in E. olivacea, E. catorce, E. juarezensis and E. perezcalixii. In contrast, E. longiflora presented 3 endocycles (8C, 16C and 32C) and E. roseiflora presented 2 endocycles (8C and 16C). It has been suggested that polyploidization and diploidization processes, together with the presence of endopolyploidy, allowed Echeveria species to adapt and colonize new adverse environments.

First Report of Pseudomonas cichorii Causing Bacterial Leaf Spot on Romaine Lettuce (Lactuca sativa var. longifolia) and Escarole (Cichorium endivia) in New Jersey.

We previously reported an outbreak of bacterial leaf spot (BLS) caused by Pseudomonas cichorii occurring on sweet basil in New Jersey during the summer of 2018 (Patel et al. 2019), a growing season characterized by increased leaf wetness due to high humidity and unusually high levels of summer rains. Leaf spot was also observed, as a one-time event, on older mature leaves on romaine and escarole lettuce during that same year. Symptoms on escarole were observed as grayish brown-to-black concentric lesions on leaf parenchyma tissue, ranging from 1 mm to 1-2 cm in diameter. In more severely diseased samples, lesions coalesced to form larger necrotic areas giving a blight appearance. On occasion, infection was observed in leaf midveins as brownish gray necrosis. Symptoms on romaine lettuce were observed mostly as coalesced blackened lesions on leaf parenchyma tissue near margins with a rotted consistency that spread to the midvein in severe cases. Margins of leaf lesions were excised and macerated in sterile water before streaking onto Nutrient Agar (NA) and King's medium B agar (KMB) (Schaad et al. 2001). Growth on both NA and KMB were predominantly cream-colored circular bacterial colonies with undulated margins. Colonies on KMB fluoresced blue under 365nm UV light. Two representative colonies isolated from each host were selected for further characterization. All isolated tested negative for levan production, positive for oxidase, negative for potato rot, negative for arginine dihydrolase, and induced a strong hypersensitive response on tobacco within 24 h, consistent with LOPAT descriptions for P. cichorii (Lelliott et al. 1966). A single strain from each host (ESC6F2 and Rom1-1) was further characterized genetically to confirm species. PCR analysis using two primers sets: 16S rRNA gene universal primers 27F/1492R and Hcr1 primers used to amplify a 520 bp region of the pathogenicity gene cluster hrcRST in P. cichorii (Patel et al. 2019; Cottyn et al. 2011). Partial 16S rDNA gene sequences were deposited in the GenBank database for each isolate (ESC6F2: MT974180; and Rom1-1: MT982172). Sequence comparisons of ESC6F2 and Rom1-1 shared 99% identity with each other and several P. cichorii strains within the GenBank database, including strain B5-2-1 isolated from sweet basil in NJ the same year (MK501753). The partial hrcRST locus (strain ESC6F2: MW048775 and Rom1-1: MW048774) shared 100% identity to each other and strain B5-2-1 (MK507764), and 99% identity with P. cichorii strain P18-1 (MH396007) isolated from Ocimum basilicum in Hawaii. Koch's postulate was performed on escarole var. Full Heart and Romaine lettuce var. Ideal Cos to confirm pathogenicity of the isolated strains. Bacterial suspensions (1x107 cfu/ml) were syringe-injected (0.1 ml) into the leaf midribs, and pressure infiltrated into leaf parenchyma tissue of 3 plants. Control plants were inoculated with sterile water. Blackened necrosis developed within 72 h around bacteria-inoculation points, which expanded beyond inoculation points within a week. In contrast, control plants remained healthy and symptomless. Although significant crop loss occurred due to BLS on escarole and romaine lettuce, P. cichorii has not been isolated from diseased plant material since 2018. This suggests inoculum sources did not persist beyond 2018, or favorable environmental conditions for disease are inconsistent to cause noticeable damage to New Jersey crops.

Description of Intra-Annual Changes in Cambial Activity and Differentiation of Secondary Conductive Tissues of Aesculus hippocastanum Trees Affected by the Leaf Miner Cameraria ohridella

Aesculus hippocastanum trees are commonly infested by the leaf miner Cameraria ohridella, whose larval activity causes the destruction of the leaf parenchyma and induces defoliation. Pest attacks result in, e.g., production of smaller fruits and tree re-flowering in autumn. Concerning pest influence on stem structure only scarce information of narrower annual growth rings of wood has been published. Therefore, we determined the effect of the presence of the leaf miner infestation on intra-annual cambial activity and on differentiation of conductive tissues. These data were compared with phenological phases and pest activity. Pest feeding resulted in changes in onset, cessation and duration of cambial divisions, and differentiation of secondary xylem. The duration of cambial activity was about a month shorter in heavily infested trees and was connected with premature tree defoliation. Affected trees were characterised by a reduction in cambial divisions and earlier cessation of wood differentiation resulting in narrower wood rings. Furthermore, the infested trees exhibited altered wood structure, with more vessels of smaller diameters, however these changes did not affect its theoretical hydraulic conductivity. Interestingly, pest attack did not influence secondary phloem differentiation. The probable influence of long-term infestation on tree growth and condition was discussed.

The implication of leaf anatomical structure for the selective breeding of lilacs.

The cultivars of the common lilac (Syringa vulgaris) grown in the south of the Russian Far East are not always winter-hardy and are often damaged by fungal diseases due to a very humid climate. A promising trend in the selective breeding of lilacs in Russia is the creation of new breeding material based on the gene pool of the broadleaf lilac (S. oblata) and its hybrids in order to introduce valuable adaptive traits into cultivars. The present work aimed to identify the traits of leaf anatomy in species and cultivars of Syringa resistant and susceptible to Pseudocercospora lilacis, the causative agent of brown leaf spot disease. The study was carried out on the living collection of the Botanical Garden-Institute, Far Eastern Branch, Russian Academy of Sciences (Vladivostok). The leaf anatomical structure of two Syringa species showing different degrees of resistance to P. lilacis in the monsoon climate of the Far East (resistant S. oblata and weakly resistant S. vulgaris, and also their hybrid cultivars) has been analyzed. The differences between species, subspecies, and cultivars are quantitative: they differ in the number of spongy mesophyll layers, the cell height in the f irst layer of palisade mesophyll, the cell height in the upper and lower epidermises, and the thickness of both mesophylls. The interspecif ic hybrids resistant or weakly resistant to P. lilacis (brown leaf spot disease) mainly retain the leaf anatomy structure of the maternal plant. One of the traits determining the resistance of hybrid lilac cultivars is an increased number of spongy mesophyll layers in the leaf blade. The study of leaf anatomy has shown that the four-layered spongy mesophyll leaf parenchyma correlates with the resistance of lilacs from the subsection Euvulgaris to P. lilacis. In S. oblata, this trait is inherited down the maternal line. To establish lilac cultivars resistant to fungal diseases, it is advisable to cross the two species (S. oblata and S. vulgaris) or their cultivars using one of S. oblata subspecies as a maternal plant.

External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana.

Exogenous application of double-stranded RNAs (dsRNAs) and small-interfering RNAs (siRNAs) to plant surfaces has emerged as a promising method for regulation of essential genes in plant pathogens and for plant disease protection. Yet, regulation of plant endogenous genes via external RNA treatments has not been sufficiently investigated. In this study, we targeted the genes of chalcone synthase (CHS), the key enzyme in the flavonoid/anthocyanin biosynthesis pathway, and two transcriptional factors, MYBL2 and ANAC032, negatively regulating anthocyanin biosynthesis in Arabidopsis. Direct foliar application of AtCHS-specific dsRNAs and siRNAs resulted in an efficient downregulation of the AtCHS gene and suppressed anthocyanin accumulation in A. thaliana under anthocyanin biosynthesis-modulating conditions. Targeting the AtMYBL2 and AtANAC032 genes by foliar dsRNA treatments markedly reduced their mRNA levels and led to a pronounced upregulation of the AtCHS gene. The content of anthocyanins was increased after treatment with AtMYBL2-dsRNA. Laser scanning microscopy showed a passage of Cy3-labeled AtCHS-dsRNA into the A. thaliana leaf vessels, leaf parenchyma cells, and stomata, indicating the dsRNA uptake and spreading into leaf tissues and plant individual cells. Together, these data show that exogenous dsRNAs were capable of downregulating Arabidopsis genes and induced relevant biochemical changes, which may have applications in plant biotechnology and gene functional studies.

Features of leaf mesostructure organization under plant growth regulators treatment on broad bean plants

It was studied the mesostructure organization of leaf apparatus and pigment content of leaves under application of growth regulators with a different mechanism of action-chlormequat chloride (1%) (retardant of quaternary ammonium compounds group) and Emistim C (0,1 ml/l) (growth stimulator) on broad bean plants. The plant growth regulators treatment on broad beans led to the thickening of leaves due to an increase in the growth of columnar and spongy leaf parenchyma. Growth regulators influenced the formation of the stomatal apparatus of broad beans leaves in different ways. The inhibitory compound chlormequat chloride caused a decrease in the number of lower epidermal cells and stomata with a simultaneous increase in the area of the stomatal cell. The application of stimulator compound Emistim C led to an increase in epidermal cells, without differences in the number of stomata but the area of stomatal cells increased significantly. It has been established the enhancement of photosynthetic processes due to an increase in the chlorophyll content in assimilative cells of leaves under chlormequat chloride on broad beans.

АНАТОМО-ДИАГНОСТИЧЕСКИЕ ПРИЗНАКИ ЛИСТЬЕВ ЛИМОНА (CITRUS LIMON (L.) BURM. F.)

The article summarizes the results of studying the anatomical structure of the leaves of a medicinal lemon plant (Citrus limon (L.) Burm. f.) from the Rutaceae family, which is used in the pharmaceutical industry to produce valuable lemon essential oil with antibacterial and antioxidant properties. There is no complete information about the anatomical structure of lemon leaves in the literature, which makes it challenging to conduct microdiagnosis of medicinal raw materials. Therefore, the study of the anatomical features of lemon leaves is relevant. The researchers took the medicinal plant material of the fresh leaves of Citrus limon from the greenhouse of the Botanical Garden named after S.I. Rostovtsev. They carried out anatomical analysis of raw materials and histochemical reactions according to the regulatory documentation of the State Pharmacopoeia of the Russian Federation. The microscopic structure showed that the leaves of Citrus limon are dorsoventral, the leaf blade is hypostomatic. The stomatal apparatus of the leaves is anomocytic. In the leaf, endogenous secretory structures were observed, represented by round-shaped lysigenic essential oil receptacles formed in the columnar and spongy mesophyll of the leaf and the main petiole parenchyma. The essential oil was synthesized in the secretory cells of the receptacle, which eventually underwent autolysis and released contents into the resulting cavity. A collateral conductive bundle with a ring-shaped cross-section represents the central vein of the leaf blade and leaf petiole. The characteristic marker features of the leaf also include the presence of single rhomboid crystals and drusen calcium oxalate in the leaf petiole mesophyll and parenchyma. As a result of the studies, significant anatomical and diagnostic signs of Citrus limon leaves were found, which can be used in writing pharmacopeia articles.

Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits.

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.

Variation in leaf anatomy, vascular traits and nanomechanical cell-wall properties among European beech (Fagus sylvatica L.) provenances

Structural and ultrastructural traits of leaf xylem vary among European beech ( Fagus sylvatica L.) provenances in relation to climate. High tracheary element lumen area was observed in central Europe and decreased towards the range margins, while tracheary element density displayed opposite trend. Leaf anatomy and xylem cell-wall deformation were associated with climate continentality at the sites of origin. Understanding structural and physiological properties of tree populations adapted to local climate in response to climate may be of direct relevance for forestry. Identifying patterns of heritable geographical variation and phenotypic associations of leaf-anatomical, vascular and cell-wall properties in European beech, a dominant tree species of European forests. Fifteen beech populations planted in a common-garden test were studied employing gas exchange and chlorophyll a fluorescence measurements as well as light and atomic force microscopies of leaf samples. Nanomechanical properties of leaf-xylem cell walls did not show a clear geographical trend, but were correlated with the temperature seasonality of the site of origin. Populations from eastern Germany, northern Poland and the Czech Republic showed lower tracheary element lumen area and higher tracheary element density compared with the other populations, while xylem conductivity negatively correlated with latitude. Thickness of leaf parenchyma layers increased towards the East and, consequently, correlated with temperature indicators of climate continentality. No correlation between structural and physiological traits was observed. The observed trends and associations with climate indicate adaptive variation of the studied traits.

Rising CO2 in the field does not offset warming or drought constraints on leaf growth of a C3 forage

AbstractThe regrowth of a C3 forage Stylosanthes capitata in a rain-fed field provided the weekly data collection in the southeast of Brazil during a heat event in autumn. A system named Trop-T-FACE simulated the free-air carbon dioxide enrichment and the enhanced temperature in four climatic regimes: current atmospheric conditions (Control), CO2 enrichment (600 ppm, eC), warming (2 °C above ambient canopy temperature, eT), and a combination of eC + eT. The area and biomass of foliage per shoot decreased, and the number of flowers per shoot and flowered ramification increased under single eC treatment besides the increment in palisade parenchyma of leaves. Increased investment in flowering in eC occurred notably when the soil water content was higher than 0.30 m3 m–3. Single eT treatment also impaired the area or biomass of foliage production per shoot, raised the shoot mortality, and promoted the increment of the spongy leaf parenchyma. There was some mitigation of the adverse effects of foliage production of eT or eC in eC + eT, but under this combined treatment, the shoot mortality also increased. Changes in leaf tissues under eC or eT or some mitigation of adverse effects in eC + eT did not offset the constraints on leaf growth per shoot. The harmful impact on foliage production by eC, eT, or eC + eT under rain-fed conditions indicated no advantages for feeding the livestock with the C3 forage S. capitata in expected climate change under field conditions.

Features of leaf mesostructure organization under plant growth regulators treatment on broad bean plants

It was studied the mesostructure organization of leaf apparatus and pigment content of leaves under application of growth regulators with a different mechanism of action-chlormequat chloride (1%) (retardant of quaternary ammonium compounds group) and Emistim C (0,1 ml/l) (growth stimulator) on broad bean plants. The plant growth regulators treatment on broad beans led to the thickening of leaves due to an increase in the growth of columnar and spongy leaf parenchyma. Growth regulators influenced the formation of the stomatal apparatus of broad beans leaves in different ways. The inhibitory compound chlormequat chloride caused a decrease in the number of lower epidermal cells and stomata with a simultaneous increase in the area of the stomatal cell. The application of stimulator compound Emistim C led to an increase in epidermal cells, without differences in the number of stomata but the area of stomatal cells increased significantly. It has been established the enhancement of photosynthetic processes due to an increase in the chlorophyll content in assimilative cells of leaves under chlormequat chloride on broad beans.

Mesophyll thickness and sclerophylly among Calotropis procera morphotypes reveal water-saved adaptation to environments

Calotropis procera (Aiton) Dryand (Apocynaceae) is a native species in tropical and subtropical Africa and Asia. However, due to its fast growing and drought-tolerant, it has become an invasive species when it was introduced into Central and South America, as well as the Caribbean Islands. Currently, C. procera displays a wide distribution in the world. Invasiveness is important, in particular, because many invasive species exert a high reproductive pressure on the invaded communities or are highly productive in their new distributed areas. It has been suggested that a very deep root system and a high capacity to reduce stomatal conductance during water shortage could allow this species to maintain the water status required for a normal function. However, the true mechanism behind the successful distribution of C. procera across wet and dry environments is still unknown. C. procera leaves were collected from 12 natural populations in Brazil, Colombia and Mexico, ranging from wet to dry environments during 2014–2015. Many traits of morphology and anatomy from these distinct morphotypes were evaluated. We found that C. procera leaves had a considerable capacity to adjust their morphological, anatomical and physiological traits to different environments. The magnitude of acclimation responses, i.e., plasticity, had been hypothesized to reflect the specialized adaptation of plant species to a particular environment. However, allometric models for leaf area (LA) estimation cannot be grouped as a single model. Leaves are narrower and thicker with low amounts of air spaces inside the leaf parenchyma in wet environments, while they are broader and thinner with a small number of palisade cell layers in dry environments. Based on these, we argue that broader and thinner leaves of C. procera dissipate incident energy at the expense of a higher rate of transpiration to survive in environments in which water is the most limiting factor and to compete in favorable wet environments.

Comparative anatomical investigation of five Artemisia L. (Anthemideae, Asteraceae) species in view of taxonomy

Comparative anatomical analysis of vegetative organs has been conducted on Artemisia campestris L., A. absinthium L., A. arborescens L., A. judaica L. and A. herba-alba Asso, using light microscopy, in order to examine the most important anatomical features and to find new valid taxonomic characters. Results have shown that general root, stem and leaf anatomical features and nonglandular and glandular trichomes are shared by all species. However, some characters (parenchyma sheath, which surrounded vascular bundle and extended to both epidermises, subepidermal collenchyma and the absence of secretory canals in the leaves) link together A. absinthium and A. arborescens from the same section. Some characters, as periderm and lignified pith parenchyma cells (A. campestris and A. arborescens), nonendodermal secretory canals in root cortex (A. absinthium and A. judaica) and secretory canals in the leaf phloem (A. judaica and A. herba-alba), connect species belonging to different sections. Moreover, some characters could be considered as species-specific, nonendodermal secretory canals in the root secondary phloem, triangular leaf shape on the cross section and secretory canals in the leaf parenchyma for A. campestris, secretory canals in the stem pith for A. absinthium, crystals in the pith parenchyma cells for A. arborescens and the absence of root secretory canals for A. herba-alba. Given results revealed qualitative characters, on the basis of which the studied species are anatomically distinguishable between each other, provide valuable features for better species identification and contribute to the anatomy of the genus Artemisia.

Morphological, anatomical, physiological and biochemical adaptations of Pittosporum tobira (Thunb.) W.T.Aiton and P. heterophyllum Franch. to the illumination level

Anatomical, morphological, physiological and biochemical adaptations of leaf as the most ecologically sensitive organ in the species P. tobira and P. heterophyllum, grown in the zones of greenhouse complex with different degree of illumination (1 zone – the level of illumination is 100–300 lx, zone 2 – 3000–7000 lx, and zone 3 – more than 10 thousand lx).) were studied. We revealed the structural morphological and anatomical adaptations, which manifested in the increase of leaf structure xeromorphy (thickening of the leaf, adaxial epidermis and columnar parenchyma, increasing pubescence density) under conditions of high insolation. With a low level of illumination in plants of both species, the thickness of the lamina decreased, mainly due to the mesophyll – the number of layers of the columnar parenchyma and the size of the cells reduced. Interspecific differences in the content of photosynthetic pigments in both species studied were found. A common trend in plants under low light conditions was decrease of chlorophyll a compared with the control, whereas the concentration of chlorophyll b in the leaves of plants increased with shading and high insolation. The result of the adaptation of the photosynthetic apparatus of Pittosporum plants, which normalizes its functioning, is a decreasing chlorophyll index both during shading and intense solar radiation. The maximum is determined in the range of 3–7 thousand lx. Such light regime is optimal for plants of the species studied. The observed decreasing pigment index in P. heterophyllum leaves is considered as an adaptive response of more light-loving species of the genus to their cultivation in the shade. The dependence of the peroxidase activity in Pittosporum leaves on the illumination level was studied. Adaptive reactions manifested in changes of peroxidase fractional composition in the leaves of the plants grown in different conditions. The obtained results on the activation and inactivation of the enzymatic activity of free and cell wall-associated peroxidase are interesting for using as an additional diagnostic indicator of stress degree for the plants of the interiors. It was established that adaptive changes in experimental plants were determined by the origin of species and their ecological and biological features.