Leaf Cross Sections Research Articles

Plant species identification using shortest paths in graphs applied to color images of palisade parenchyma

Aiming to identify plants, we propose to evaluate the color texture of the palisade parenchyma, from microscopic images of leaf cross-sections, using a graph based approach. Our texture analysis approach models the image texture as a graph and uses measurements computed from the shortest paths between specific vertices to provide a feasible texture signature. For a more consistent evaluation, we compared our approach to different methods for color texture analysis in a texture classification experiment. The results obtained indicate that our approach is the most suitable for this histological analysis as it surpassed all the other texture approaches using Linear Discriminant Analysis, and obtained the second best accuracy using 1-Nearest Neighbor. These results also corroborate the feasibility of using both histological (as the palisade parenchyma) and computer analysis for identification and delimitation of plant taxa.

Effect of salicylic acid on photochemistry and antioxidant capacity in Salvia nemorosa plants subjected to water stress.

Oxidative stress is commonly induced when plants are grown under drought stress conditions.To analyze how salicylic acid (SA) can partly alleviate drought-induced oxidative stress and negative impacts of drought on physiology and growth of Salvia nemorosa plants, we investigated the physiological responses of S. nemorosa to SA application under drought stress. The treatments were composed of Co (control, 100% field capacity), Dr (drought, 50% field capacity), SA (500 µM) and DSA (SA + drought). Plant growth and relative water content (RWC) were negatively affected by drought stress; however, SA treatment significantly improved the growth rate and enhanced the drought tolerance of seedlings. This increased tolerance in SA-supplied plants was obtained by reduced damaging effect on performance index (PIabs) and maximal quantum yield of photosystem II (PSII) (Fv/Fm) through improvement of reaction centers (RC/CS) with associated changes in excitation energy trapping (TRo/CS) and electron transport (ET0/CS) per excited cross-section of leaf. Additionally, under drought condition, plants cultivated with SA exhibited better protection against oxidative damage because of higher catalase (CAT) and ascorbate peroxidase (APX) activities and lower levels of malondoialdehyde (MDA) and hydrogen peroxide (H2O2). The present study suggests that salicylic acid can play a protective role during drought stress by enhancing the photosynthetic capacity and the antioxidant defense system.

The light response of mesophyll conductance is controlled by structure across leaf profiles.

Mesophyll conductance to CO2 (gm ) may respond to light either through regulated dynamic mechanisms or due to anatomical and structural factors. At low light, some layers of cells in the leaf cross-section approach photocompensation and contribute minimally to bulk leaf photosynthesis and little to whole leaf gm (gm,leaf ). Thus, the bulk gm,leaf will appear to respond to light despite being based upon cells having an anatomically fixed mesophyll conductance. Such behaviour was observed in species with contrasting leaf structure using the variable J or stable isotope method of measuring gm,leaf . A species with bifacial structure, Arbutus × 'Marina', and an isobilateral species, Triticum durum L., had contrasting responses of gm,leaf upon varying adaxial or abaxial illumination. Anatomical observations, when coupled with the proposed model of gm,leaf to photosynthetic photon flux density (PPFD) response, successfully represented the observed gas exchange data. The theoretical and observed evidence that gm,leaf apparently responds to light has large implications for how gm,leaf values are interpreted, particularly limitation analyses, and indicates the importance of measuring gm under full light saturation. Responses of gm,leaf to the environment should be treated as an emergent property of a distributed 3D structure, and not solely a leaf area-based phenomenon.

Vegetative Anatomy of the Haemodoraceae and Its Phylogenetic Significance

Premise of research. Haemodoraceae are a relatively small monocot family consisting of 14 genera and approximately 108 species and are distributed in parts of Australia, southern Africa, South and Central America, and eastern North America. The family is divided into two subfamilies, Haemodoroideae and Conostylidoideae. This research focuses on the vegetative anatomy of the family, with an emphasis on leaf anatomical features. The aims of this project are (1) to acquire new vegetative anatomical data for a large selection of Haemodoraceae and (2) to evaluate these data in the context of both phylogenetic relationships and environmental factors.Methodology. Cross sections of roots, stems (scapes), or leaves of 60 species and 63 ranked taxa from all 14 genera of the family were prepared and stained using standard histological methods, and SEMs were made of the leaf surface. Line drawings were prepared of leaf cross sections of an exemplar of each genus. Tissues and cells were examined and photographed, and comparisons were made among taxa. For leaf epidermal cells, the ratio of cell wall transectional area∶cell transectional area was calculated and plotted. Several discrete anatomical characters and character states were defined and plotted on a recently derived cladogram and examined for phylogenetic signal. Correlation of certain anatomical features with environmental factors was also noted.Pivotal results. Leaf anatomy provides several phylogenetically informative traits, including bulliform cells, tannin cells, marginal fiber caps, the relative wall transectional area of epidermal cells, the morphology of palisade cells, the distribution of fibers in the vascular bundle, leaf aerenchyma, mucilage cells, and silica bodies. These features generally correlate significantly with the pattern of phylogenetic relationships in the family. Silica cells, tannin cells, and mucilage cells, all of which may function to deter herbivory, are generally restricted to particular clades. The relative epidermal wall thickness of members of the genus Conostylis is significantly higher than in other members of the family, a feature that may represent an adaptation to their hot, dry environments.Conclusions. The systematic and ecological value of studying plant vegetative anatomy is supported by this study. Vegetative anatomical features of the Haemodoraceae show considerable and significant variation. Numerous anatomical features exhibit a high phylogenetic signal and are apomorphic for specific clades. Some anatomical features are possible adaptations to habitat, climate, or herbivory. However, quantifiable ecological data are needed in future studies for assessing the adaptive significance of these anatomical features.

Anatomical, Histochemical and Cytogenetic Features of <i>Doryopteris triphylla</i> (Pteridaceae)

Doryopteris triphylla (Pteridaceae-Cheilanthoideae) grows in xeric habitats in Brazil, Paraguay, Uruguay and Argentina. The aim of this study was to characterize D. triphylla anatomically, histochemically and cytogenetically. For anatomical characterization, rhizomes, roots, petioles and leaves were made and then stained using Safranine-Astra Blue for further observations. Leaf blades were also cleared. For histochemical analysis, leaf cross sections were stained with different reagents to identify glandular trichomes compounds. For cytogenetic characterization, a karyogram was performed using laboratory cultivated roots. Results show a dictyostelic rhizome covered with scales with apical secreting gland; diarch roots; petiole cross-sections show thick cuticle, uniseriate epidermis, parenchymatic cortex cells with thick walls and a vascular bundle with two xylem groups; and hypostomatic fronds with glandular trichomes. Histochemical studies of secretion products of the glandular trichomes were positive for polysaccharides, pectins, lipids, acid lipids, dihydroxyphenols, phenols and flavonoids. Cytogenetically, D. triphylla is described as a diploid species (2n = 60), with chromosomes gradually decreasing in size. The apical glands in scales of rhizomes, the presence of two xylem groups in the vascular bundle in the petiole and the glandular trichomes on the abaxial surface are new contributions to the species. The type of chemical products secreted by glandular leaf trichomes and karyotype estimation is shown for the first time in this species.

Gymnomitrion fissum (Gymnomitriaceae, Marchantiophyta) — a new species with fissured leaf surface from China

Study of selected specimens of Gymnomitrion collected by D. G. Long in Yunnan, China, revealed a new species, G. fissum Mamontov et Potemkin, sp. nov., with a fissured leaf surface. Comparison of SEM images of the leaf surface and leaf cross sections shows that the leaf surface of G. fissum is different from that of other known species with a superficially similar leaf surface, i. e. Mylia taylorii, M. verrucosa s. l. and Trabacellula tumidula. It has fissures around the cell lumen rather than grids and perforations. Outer cell walls of Gymnomitrion fissum are much thicker than in Mylia taylorii, M. verrucosa s. l. and Trabacellula tumidula, and their outer layers tend to be partly or completely caducous. G. fissum is related to the group of species assigned to the former genus Apomarsupella.

Nitrogen Limitation Adaptation (NLA) is involved in source-to-sink remobilization of nitrate by mediating the degradation of NRT1.7 in Arabidopsis.

Recent studies on nitrate transporters (NRTs) have greatly increased our knowledge of the mechanisms regulating nitrogen (N) homeostasis in plants. However, an understanding of how these NRTs are regulated is still lacking. The nitrogen limitation adaptation (nla) mutant is hypersensitive to N limitation. In the nla mutant, 15 N-nitrate spotted on old leaves preferentially accumulated in the youngest leaves. Analysis of leaf cross-sections indicated that NLA expression was expressed in the sieve element and companion cell system. The results of bimolecular fluorescence complementation (BiFC), split-ubiquitin yeast two-hybrid and co-immunoprecipitation (CoIP) assays demonstrated that NLA interacts with NRT1.7 in the plasma membrane. The following findings suggest that NLA directs the ubiquitination of NRT1.7: the down-regulation of NRT1.7 protein abundance in 35S::NLA/35S::Myc-NRT1.7 double transgenic plants compared with 35S::Myc-NRT1.7 transgenic plants; the up-regulation of NRT1.7 protein abundance in the nla mutant compared with wild-type plants; and the direct degradation of truncated NRT1.7 recombinant protein by NLA. Furthermore, analysis of NLA and NRT1.7 protein abundance in mirna827 knock-out plants showed that N deficiency-guided translational repression of NLA depends on miRNA827. Our findings reveal that plants regulate source-to-sink remobilization of nitrate by the ubiquitin-mediated post-translational regulatory pathway.

Characterization of S-nitrosoglutathione reductase from Brassica and Lactuca spp. and its modulation during plant development

Cellular homeostasis of S-nitrosoglutathione (GSNO), a major cache of nitric oxide bioactivity in plants, is controlled by the NADH-dependent S-nitrosoglutathione reductase (GSNOR) belonging to the family of class III alcohol dehydrogenases (EC 1.1.1.1). GSNOR is a key regulator of S-nitrosothiol metabolism and is involved in plant responses to abiotic and biotic stresses. This study was focused on GSNOR from two important crop plants, cauliflower (Brassica oleracea var. botrytis, BoGSNOR) and lettuce (Lactuca sativa, LsGSNOR). Both purified recombinant GSNORs were characterized in vitro and found to exists as dimers, exhibit high thermal stability and substrate preference towards GSNO, although both enzymes have dehydrogenase activity with a broad range of long-chain alcohols and ω-hydroxy fatty acids in presence of NAD+. Data on enzyme affinities to their cofactors NADH and NAD+ obtained by isothermal titration calorimetry suggest the high affinity to NADH might underline the GSNOR capacity to function in the intracellular environment. GSNOR activity and gene expression peak during early developmental stages of lettuce and cauliflower at 20 and 30 days after germination, respectively. GSNOR activity was also measured in four other Lactuca spp. genotypes with different degree of resistance to biotrophic pathogen Bremia lactucae. Higher GSNOR activities were found in non-infected plants of susceptible genotypes L. sativa UCDM2 and L. serriola as compared to resistant genotypes. GSNOR and GSNO were localized by confocal laser scanning microscopy in vascular bundles and in epidermal and parenchymal cells of leaf cross-sections. The presented results bring new insight in the role of GSNOR in the regulation of S-nitrosothiol levels in plant growth and development.

Pharmacobotanical study of Hypericum thymopsis

Hypericum thymopsis Boiss., Hypericaceae, is an endemic herb which generally grows at the calcareous steppe regions of Central Turkey. In flowering stage, the aerial parts of this species are used for wound-healing and sedation, and its infusions are used against stomach diseases and throat infections by local people. The aim of this study, to examine and to reveal of the morphology, anatomy and histology of the aerial vegetative and reproductive organs of the H. thymopsis, which are used in popular medicine and thus contributing to the pharmacognostic evaluation of the species. In comparison with previous published morphological description of the species, some different findings about plant height and leaf length were found. In addition, some morphological characteristics such as dimensions of sepals and ovaries, length of filaments, anthers, pistils and pedicels were examined here for the first time. The anatomical characteristics of stem, leaf, sepal, filament and pistil were studied using light microscopy and additionally for stem and leaf using scanning electron microscopy. The stem has the secondary growth, and circular shape. The leaves are amphistomatic and the mesophyll is dorsiventral. Stomata are anisocytic and sunken. The glandiferous emergences are present on stem and translucent glands exist in leaf mesophyll. Type A secretory canals are present in stem, leaf, sepal and petal cross section. While type B secretory canals are observed in sepal and petal, type C secretory canals are observed solely in ovary cross section. All the structural features herein found can assist the diagnosis of H. thymopsis.

مطالعه صفات تشریحی برگ و دمبرگ سرده Alchemilla از تیره گل سرخیان در ایران و کاربرد آنها در تاکسونومی عددی

The current study deals with leaf and petiole anatomical survey of 24 species of the genus Alchemilla from Iran. After collecting and identifying the specimens, leaf and petiole cross sections were prepared by hand and best sections were taken for staining and light microscope studies. In this survey, 43 anatomical traits were carefully examined. The result showed that glandular trichome, number and arrangement of adjacent epidermal cells and their wavy or smooth walls, presence and absence of the extraxylary fibers are the most outstanding anatomical evidences. In order to determine the species relationship, 39 quantitative characters were undertaken in principal component analysis (PCA). PCA analysis led to complete separation of some species including A. persica, A. caucasica, A. hessii, A. pseudocartalinica, A. rechingeri, A. melancholica, A. hyrcana, A. microscopica and A. erythropoda, formation of 3 main groups and two subgroups. Our findings revealed that leaf and petiole anatomical characters are limited taxonomic value. The numerical analysis of these traits has disability in revealing the species relationship.

Phenetic Variation and Preliminary Phytochemical Screening of Piper Species in Sri Lanka

The genus Piper has high commercial importance as it contains cultivated crops (black pepper and betel) and medicinal plants that are mostly used in traditional medicine. In Sri Lanka the genus Piper is represented by ten species including five wild species. It is necessary to examine their chemical composition and morphology as they have received little attention for utilizing their valuable traits for crop improvement. Piper nigrum L., P. betle L., P. longum L., P. chuvya (Miq.) C. DC., P. siriboa L., P. sylvestre Lam., P. zeylanicum Miq. P. walkeri Miq were subjected to morphological and phytochemical study using the specimens collected from natural habitats and from the cultivations. The air dried and powdered leaves were used for qualitative phytochemical screening. Qualitative phytochemical screening was carried out to identify the different chemical compounds in petroleum ether, chloroform, methanol and water. The study confirmed the presence of tannins, flavonoids, terpenoids, glycosides, alkaloids and phenolic compounds. Anatomical studies were carried out by obtaining leaf epidermal peels and cross sections. Thirteen morphological and anatomical characters were subjected to cluster analysis using PAST software to infer their relationships. According to the phenogram (Single linkage, Euclidean distance) the taxa were divided into two main clusters; P. longum , P. zeylanicum , P. sylvestre , P. nigrum and P. walkeri formed one cluster whereas P. chuvya , P. betle , P. siriboa formed the other cluster sharing similarities. P. betle varieties were clustered together with P. siriboa and P. chuvya within the second cluster. Therefore, potential strengths in disease resistance of P. siriboa and P. chuvya can be used to develop improved varieties of betel to minimize economic losses due to epidemics in cultivations.

Taxonomic remarks on the genus Sternbergia L. (Amaryllidaceae) in Turkey based on leaf anatomy, karyosystematic analysis and nuclear DNA content

Anatomy of leaf cross sections, karyological studies, and nuclear DNA content analysis by flow cytometry were carried out on the six Sternbergia species from Turkey: S. candida (endemic to the country), S. clusiana, S. colchiciflora, S. lutea, S. sicula and S. vernalis. In karyological analysis, number and morphology of the somatic chromosomes, the ploidy level and karyotype formula of the specimens used in the study were investigated in detail. The measurements of somatic chromosomes were calculated with formula of the relative variation in chromosome lenght (CVCL) and mean centromeric asymmetry (MCA). According to the results of this study, there are two different basic chromosome numbers. i.e. x = 10 (S. candida, S. clusiana, S. colchiciflora and S. vernalis) and x = 11 (S. lutea and S. sicula). Results of karyotype analysis corroborated results of previous studies. The smallest chromosome length was measured as 3.05 μm in S. clusiana while the longest length of 20.89 μm was observed in S. sicula. This is the first study reporting nuclear DNA content results for Sternbergia. Based on results of the nuclear DNA content analysis, there is a great variation within the genus in the interspecific level as 2C DNA content varies between 54.03 and 80.42 pg among the species investigated in the study. Anatomical features of the leaves were good taxonomic markers, especially concerning their palisade cells, ribs, cuticle, laticifer canals, vascular bundles, crystals, stomatal index, and stomata structure. Analytical drawings were presented. Six noteworthy leaf characters were quantified, organized in a data matrix, and analysed with UPGMA methods. In conclusion, cytological characteristics of the Sternbergia species together with their leaf features proved to be quite useful in identification and therefore can provide more clarity for taxonomic revision of the genus.

OsLBD3-7 Overexpression Induced Adaxially Rolled Leaves in Rice.

Appropriate leaf rolling enhances erect-leaf habits and photosynthetic efficiency, which consequently improves grain yield. Here, we reported the novel lateral organ boundaries domain (LBD) gene OsLBD3-7, which is involved in the regulation of leaf rolling. OsLBD3-7 works as a transcription activator and its protein is located on the plasma membrane and in the nucleus. Overexpression of OsLBD3-7 leads to narrow and adaxially rolled leaves. Microscopy of flag leaf cross-sections indicated that overexpression of OsLBD3-7 led to a decrease in both bulliform cell size and number. Transcriptional analysis showed that key genes that had been reported to be negative regulators of bulliform cell development were up-regulated in transgenic plants. These results indicated that OsLBD3-7 might acts as an upstream regulatory gene of bulliform cell development to regulate leaf rolling, which will give more insights on the leaf rolling regulation mechanism.

Morpho-anatomical investigations on Momordica charantia L. (Cucurbitaceae)

Momordica charantia L. (Cucurbitaceae) used for some medicinal purposes like antidiabetic, anticancer, antiviral and treat to gastritis was investigated. Morphological studies were supported by morphometric measurements and drawings of male and female flowers, fruit and seeds of the species. In anatomical studies, cross sections of stem and leaf, upper and lower surface sections of leaves were evaluated. It was detected that the stem with typical anatomical properties of a climbing dicotyl plant. The leaves were amphistotamic and with lots of cyctoliths on the lower surface of leaves. Stomata are anomocytic and situated much more at the lower surface of leaves. Morpho-anatomical investigations on Momordica charantia L. (Cucurbitaceae)*

A review of the genus Nymphoides (Menyanthaceae) in Iran

The genus Nymphoides is a freshwater aquatic dicot represented by two species in Iran. Based on our current regional taxonomic revision of this genus, we recognize Nymphoides cristata, previously identified as Nymphoides indica in Flora Iranica. However, these species are easily distinguished from each other by having crested petal lobes in the latter. We investigated the morphology and anatomy of Nymphoides cristata and Nymphoides peltata. The most important morphological features for differentiation between these species are corolla color and inflorescence type. The anatomy of cross-sections of leaf, petiole, stem and the surface sections of leaf were studied. The following characters were found to be taxonomically informative: the presence of stellate, polyramous and ramiform foliar sclereids as well as the presence of astrosclereids in petioles and stems of both examined taxa, while spheroidal sclereids are only observed in the stems of Nymphoides peltata.

Effect of foliar-applied silicon on photochemistry, antioxidant capacity and growth in maize plants subjected to chilling stress

Low temperature is one of the major adverse climatic factors that suppress plant growth and sustainable agricultural development. In these climate conditions, silicon (Si) can mitigate various abiotic stresses including low temperature. In this study, the roles of foliar-applied silicon (10 mM potassium metasilicate) in enhancing tolerance to chilling stress were investigated in maize (Zea mays ‘Fajr’) plants. The low temperature stress caused significant reduction of plant growth and relative water content; however, Si ameliorated these effects. Si supply in maize exhibited a significantly positive effect on accumulation of free amino acids, and reduced the necrotic leaf area. The decrease in maximum quantum yield of PSII (Fv/Fm) was reversible during recovery, but not in the non-Si-treated leaves. This can be explained by enhancement of protective pigments; carotenoid and anthocyanin leading to the protection of PSII from damage. Additionally, analysis of OJIP transients revealed that Si reduced cold damaging effect on performance index (PIabs) and Fv/Fm through improvement of excitation energy trapping (TR0/CS) and electron transport (ET0/CS) per excited cross-section of leaf. The malondialdehyde (MDA) concentration, which was significantly increased under chilling stress, was decreased by Si. The reduced glutathione and ascorbate concentrations were higher in Si-treated plants as compared to those without application of Si under chilling stress. These results indicated that Si could enhance the chilling stress tolerance of maize plants through improving the biomass accumulation, maintaining a high level of glutathione, ascorbic acid, protein, protective pigments, and enhancing the photochemical reactions. This study also suggests that the foliar-applied Si increases recovery ability from chilling injury.

Leaf Blade Anatomy of Philippine Medinilla Gaudich. Species in Relation to their Epiphytic Habit

Leaf anatomy of four epiphytic species of Philippine Medinilla , namely, M. magnifica Lindl., M. miniata Merr., M. pendula Merr., and M. teysmannii Miq., was characterized by observation of leaf cross sections prepared through paraffin method. Similarities among the four species revealed by this study include thick hypodermis below the upper epidermis, palisade mesophyll comprising one layer of elongated lignified parenchyma cells, spongy mesophyll with scarce air spaces, and polocytic stomates present only in the lower epidermis. These features aid in water conservation which is highly crucial among epiphytes. Presence of druse crystals in all four species was observed. This feature functions for structural support, defense against herbivory, calcium storage, and increasing photosynthetic efficiency. In hypodermis, number of cell layers, cell shape, and relative thickness vary among the four species in this study. The spongy mesophyll of the four species differ in number of cell layers. Because these variations can differentiate these species from one another, they are deemed to be useful in taxonomy. This study shows that anatomical features of the Medinilla species used in this study are related to their epiphytic nature and their occurrence in the forest understory. Keywords: Medinilla , epiphyte, sclerified mesophyll, hypodermis, druse, polocytic stomates

Anatomical characteristics and tissue localization of various flavonoid subclasses in Cotinus coggygria stem and leaf cross-sections

Leaves, twigs and wood of Cotinus coggygria (Anacardiaceae) are employed in European and Chinese traditional medicine to treat skin and mucosal injuries, fever, diarrhea, emesis and to enhance appetite. While being a popular medicinal plant, ancient tinctorial species and common ornamental shrub, its anatomical characteristics and tissue localization of major groups of active compounds have not been studied yet, to the best of our knowledge. Freehand cross sections of the stem at different developmental stages, leaf lamina and petiole were performed. Tissue types were studied using conventional dyes (toluidine blue; congo red and malachite green). Folin-Ciocalteu reagent, shift reagents (ammonia) and Naturstoffreagenz A were used to complement light microscopy and autofluorescence observations of flavonoid localization. Microscopes of type Optika XDS-3FL inverted fluorescence, and Olympus BH-2 for observation in visible light were employed. C. coggygria stem has a typical secondary structure. The bark contains resin ducts placed in the phloem; in younger twigs they are limited by outer sclerenchyma arches. Vascular cambium generates distinct annual rings, with a porous structure. The vessel frequency is of 100 – 200 mm2, and their perforations are simple. Medullar rays are narrow (1 – 2 cells). Chalcone and aurone derivatives are present in inner wood rings aged at least 2 years, in earlywood parts. Leaves display epidermis with anomocytic stomata on the lower surface. A hypodermis is present on the adaxial side. The midrib contains four main vascular bundles and cambium. The phloem encloses resin secretory cavities. The center of the midrib is occupied by parenchyma. Palisade parenchyma is two cells deep, and spongy mesophyll is situated towards the abaxial side. Reducing flavonoids are present in leaf mesophyll.

“Rolled-upness”: phenotyping leaf rolling in cereals using computer vision and functional data analysis approaches

Background The flag leaf of a wheat (Triticum aestivum L.) plant rolls up into a cylinder in response to drought conditions and then unrolls when leaf water relations improve. This is a desirable trait for extending leaf area duration and improving grain size particularly under drought. But how do we quantify this phenotype so that different varieties of wheat or different treatments can be compared objectively since this phenotype can easily be confounded with inter-genotypic differences in root-water uptake and/or transpiration at the leaf level if using traditional methods?Results We present a new method to objectively test a range of lines/varieties/treatments for their propensity of leaves to roll. We have designed a repeatable protocol and defined an objective measure of leaf curvature called “rolled-upness” which minimises confounding factors in the assessment of leaf rolling in grass species. We induced leaf rolling by immersing leaf strips in an osmoticum of known osmotic pressure. Using micro-photographs of individual leaf cross-sections at equilibrium in the osmoticum, two approaches were used to quantify leaf rolling. The first was to use some properties of the convex hull of the leaf cross-section. The second was to use cubic smoothing splines to approximate the transverse leaf shape mathematically and then use a statistic derived from the splines for comparison. Both approaches resulted in objective measurements that could differentiate clearly between breeding lines and varieties contrasting genetically in their propensity for leaf rolling under water stress. The spline approach distinguished between upward and downward curvature and allowed detailed properties of the rolling to be examined, such as the position on the strip where maximum curvature occurs.ConclusionsA method applying smoothing splines to skeletonised images of transverse wheat leaf sections enabled objective measurements of inter-genotypic variation for hydronastic leaf rolling in wheat. Mean-curvature of the leaf cross-section was the measure selected to discriminate between genotypes, as it was straightforward to calculate and easily construed. The method has broad applicability and provides an avenue to genetically dissect the trait in cereals.Electronic supplementary materialThe online version of this article (doi:10.1186/s13007-015-0095-1) contains supplementary material, which is available to authorized users.

Environmental Effect on the Leaf Morphology and Anatomy of Berberis microphylla G. Forst

Berberis microphylla G. Forst is a fruit shrub native from Patagonia, considered as a non-timber forest product. In recent years, there has been an increased demand for its fruits, both for fresh and industrialized consumption, being the establishment of commercial orchards in different sites a need to meet this demand. B. microphylla cloned plants have been introduced from Ushuaia, Tierra del Fuego to Buenos Aires province in order to evaluate its phenotypic plasticity and the possibility of fruit production. At the same time, a comparative study on the morphology and anatomy of the mature leaves of B. microphylla grown in two different environmental conditions was carried out. Moreno leaves were significantly larger than Ushuaia leaves in all the morphological parameters registered, while Ushuaia leaves were more circular than Moreno leaves with the highest roundness and elongation indexes. Nevertheless, histological sections showed that Ushuaia leaves have one more layer of palisade cells respect to Moreno leaves. Ushuaia leaves showed higher palisade cells, larger abaxial epidermal cells and thicker cuticles than Moreno leaves. The stomatal density was superior on Moreno leaves. Scanning Electron Microscope of abaxial epidermis showed a surface with numerous ridges of different forms that prevent the layout of epidermal cells on Moreno leaves. Appearance of this surface is glossy and oily. On the contrary, epidermal cells are well recognized on Ushuaia leaves. Stomata of anomocytic type were observed and surface looks waxy. Auto-fluorescence on leaf cross sections were observed on the vascular bundles and partially on the epidermis cells. B. microphylla leaves showed a high phenotypic plasticity between the two sites of cultivation. The changes in the leaf morphology and structure observed in Moreno leaves could indicate that the plants are trying to adjust its morphology to the new culture conditions i.e. higher temperatures and lower irradiance.