Epidermal Cell Width Research Articles

Lamiales epidermal dynamics: Unveiling antimicrobial resilience in a structural symphony.

This research on Lamiales epidermal anatomy not only provides in-depth understanding of their structural traits but also highlights the significance of uncovering the inherent antimicrobial resilience embedded within these plants. Such insights hold promise for advancing natural product-based approaches in medicine, potentially contributing to the development of novel antimicrobial agents inspired by Lamiales unique biological defense mechanisms. Scanning microscopic tools were utilized to conduct foliar epidermal anatomy of nine species that belong to seven genera and four families within the Lamiales order, Plantaginaceae, Scrophulariaceae, Verbenaceae, and Lamiaceae. This approach aimed to gather both qualitative and quantitative data, facilitating the assessment of taxonomic microanatomical significance. The shape of epidermal cells and their anticlinal walls; number of epidermal cells, stomata, and trichomes; type of stomata and trichomes; length and width of epidermal cells, trichomes, stomatal pore, guard cells, and subsidiary cells; and stomatal index were determined statistically. Most of the species examined were amphistomatous and showed extensive array of trichomes diversity. The exploration of Lamiales epidermal micromorphology and their antimicrobial potential were significant for their implications in multidisciplinary fields. The pharmacological research to utilize sustainable agricultural practices prompts avenues to strengths of Lamiales order for the development of novel antimicrobial solutions and ecological benefits. RESEARCH HIGHLIGHTS: Diverse trichome morphometry reveals a wide array of trichome structures across Lamiales species. Epidermal microscopic architecture variability of epidermal cell shapes and sizes signifies the interspecies variability. Secondary metabolite localization within microanatomical structures elucidates potential hotspots for antimicrobial compound production.

Effect of shading on trichome formation and CAPRICE-like gene expression in tea (Camellia sinensis var. sinensis) leaves

Tea (Camellia sinensis var. sinensis) is one of the most popular beverages worldwide and is highly regarded for its unique taste and health benefits. The traditional practice of shading tea plants before harvest is employed to ensure the production of high-quality Japanese green tea. However, the precise effects of shading on trichome formation, leaf tissue structure, and the expression of related genes remain largely unknown. In the present study, we conducted a comparative analysis to investigate the effect of shading on the aforementioned aspects of tea leaves. Our findings revealed a significant decrease in the number of trichomes in the youngest 1st stage leaves under shaded conditions compared with that under full-light conditions. Histological analyses revealed that epidermal cells in tea leaves under shaded conditions were thinner, further indicating the influence of light on leaf structures. To delve deeper into the regulatory mechanisms, the expression levels of six Camellia sinensis CAPRICE (CsCPC) genes encoding R3 MYB transcription factors, which have been implicated in trichome formation in tea plants, were examined using real-time reverse transcription PCR. Among the six genes, CsCPC-1, Camellia sinensis ENHANCER OF TRY AND CPC 1–2 (CsETC1–2), and CsETC3 exhibited increased expression under shaded conditions, indicating their potential involvement in the light-mediated regulation of tea leaf characteristics. The expression levels of the phenylpropanoid pathway structural genes Camellia sinensis cinnamic acid 4-hydroxylase (CsC4H), Camellia sinensis cinnamoyl CoA reductase (CsCCR), and Camellia sinensis flavanone 3′ hydroxylase (CsF3′H), were significantly reduced under shaded conditions, suggesting the regulation of phenylpropanoid content. Our study demonstrated that shading treatment induces significant changes in the number of trichomes in younger leaves, alters the width of epidermal cells, and affects the expression levels of CsCPCs and genes related to the phenylpropanoid pathway. These findings have the potential to enhance tea leaf quality, and offer pragmatic implications for tea farming.

SMALL PLANT AND ORGAN 1 (SPO1) Encoding a Cellulose Synthase-like Protein D4 (OsCSLD4) Is an Important Regulator for Plant Architecture and Organ Size in Rice

Plant architecture and organ size are considered as important traits in crop breeding and germplasm improvement. Although several factors affecting plant architecture and organ size have been identified in rice, the genetic and regulatory mechanisms remain to be elucidated. Here, we identified and characterized the small plant and organ 1 (spo1) mutant in rice (Oryza sativa), which exhibits narrow and rolled leaf, reductions in plant height, root length, and grain width, and other morphological defects. Map-based cloning revealed that SPO1 is allelic with OsCSLD4, a gene encoding the cellulose synthase-like protein D4, and is highly expressed in the roots at the seedling and tillering stages. Microscopic observation revealed the spo1 mutant had reduced number and width in leaf veins, smaller size of leaf bulliform cells, reduced cell length and cell area in the culm, and decreased width of epidermal cells in the outer glume of the grain. These results indicate the role of SPO1 in modulating cell division and cell expansion, which modulates plant architecture and organ size. It is showed that the contents of endogenous hormones including auxin, abscisic acid, gibberellin, and zeatin tested in the spo1 mutant were significantly altered, compared to the wild type. Furthermore, the transcriptome analysis revealed that the differentially expressed genes (DEGs) are significantly enriched in the pathways associated with plant hormone signal transduction, cell cycle progression, and cell wall formation. These results indicated that the loss of SPO1/OsCSLD4 function disrupted cell wall cellulose synthase and hormones homeostasis and signaling, thus leading to smaller plant and organ size in spo1. Taken together, we suggest the functional role of SPO1/OsCSLD4 in the control of rice plant and organ size by modulating cell division and expansion, likely through the effects of multiple hormonal pathways on cell wall formation.

Light and scanning electron microscopic characterization of thirty endemic Fabaceae species of district Lahore, Pakistan.

In the present study anatomical characterization of 30 species of Fabaceae endemic to Lahore, Pakistan were done under light and scanning electron microscopy. Variety of qualitative and quantitative anatomical characters like epidermal cells shapes and size, stomata types, length, and width of guard cells, subsidiary cells, trichomes, silica bodies, shapes, and their numbers were studied. Overall polygonal, irregular smooth, thick walled epidermal cells were observed at both abaxial and adaxial surfaces except Dalbergia sisso Roxb in which hexagonal epidermal cells were reported. Milletia ovelifolia Kurz. possessed the largest length of epidermal cell i.e., 273.1 μm whereas Calliandra bella Benth. showed the smallest length i.e., 76.5 μm. Average width of epidermal cells ranged from 44 to 265.5 μm. M. ovelifolia Kurz had largest width while Acacia nilotica L. had the smallest width respectively. In adaxial surface epidermal cells length ranged 317 to 46.4 μm, Glycyrriza glabra L. showed the smallest length whereas Prosopis juliflora DC. had largest length. In adaxial numbers of stomata is high as compare to the abaxial surface, mostly paracytic, anisocytic, and anomocytic stomata were observed. There is not much variations observed in trichomes of studied members. Generally non glandular, unbranched, uniserate, mulicellular bulbous base with pointed tips were reported . Oval, rounded, triangular shaped silica bodies were observed in some species. It is concluded that qualitative and quantitative anatomical variations in epidermal cells, stomata and trichomes are of good taxonomic value for the studied Fabaceae species.

Spore morphology and leaf epidermal anatomy as a taxonomic source in the identification of Asplenium species from Malakand division Pakistan.

Several studies have demonstrated the usefulness of leaf epidermal, and spore morphological characters in the taxonomy of genus Asplenium. However, works on the Pakistani species of Asplenium are not existent. With the objective to verify the efficacy of leaf epidermal and spore morphological traits, the leaf epidermis and spore morphology in nine Asplenium species occurring in Malakand division was studied. The spores were studied under light microscope (LM) and scanning electron microscope (SEM), whereas for leaf epidermal anatomy, the LM was used. The spores are monolete, ellipsoidal in shape, the equatorial and polar diameter ranges between 28.3 and 50.2 × 27.6 and 45.8 μm. The exospore thickness varied from 0.5 to 3.8 μm. The perispore is 0.8-3.5 μm thick, ornamented, and morphologically variable. The spores characters specifically the perispore ornamentation are useful in distinguishing species within the genus. The irregular spore shape and unusual development of perispore wall surface characterize aborted spores in the species of Asplenium × alternifolium. The most informative quantitative characters appeared to be length and width of epidermal cells, and length and width of stomata were useful to distinguish species. The most significant qualitative characters to distinguish species were the anticlinal wall pattern. Our study has shown that considerable variations exist in the leaf epidermis of Asplenium species, at least some of which has taxonomic significance. We confirmed the prevalent taxonomic value of stomatal and epidermal cells traits. The leaf epidermal anatomy and spore morphological features showed to be a good source of information for taxonomy of the genus Asplenium.

Scanning electron microscopic screening of 20 medicinally important Asteroideae taxa.

In the present study anatomical characterization of 20 medicinally important Asteroideae species were done under light and scanning electron microscopy. Variety of qualitative and quantitative anatomical characters like epidermal cells, stomata, guard cells, subsidiary cells, trichomes and oil droplets were observed. Generally pentagonal, polygonal, irregular or hexagonal, smooth, undulating thick walled epidermal cells were observed in studied species. In abaxial surface Thymophylla tenuiloba L. possessed the largest length of epidermal cell that is, 221.6 (156.6-286.6) μm whereas Bellis perenis L. showed the smallest length that is, 46.4 (32.6-60.2) μm. Average width of epidermal cells ranged from 57 (22-92) μm to 169 (127.9-210.1) μm. Cosmos sulphureus Cav. had smallest width while Thymophylla tenuiloba L. had the largest width. In adaxial surface Artemisia absinthium L. possessed the largest length of epidermal cell that is, 269 (165.1-372.9) μm whereas Bellis perenis L. showed the smallest length that is, 61.4 (42.6-80.2) μm. Average width of epidermal cells ranged from 50.8 (32.6-69) μm to 260 (116-202) μm. Thymophylla tenuiloba L. had smallest width while Dahlia pinnata Cav. had the largest width. Among stomatal characters anisocytic, anomocytic, and diacytic stomata were observed in selected species of Asteroideae. Nonglandular uniserate, multicellular, unbranched pointed tips with bulbous base trichomes were reported in some Asteroideae members while some possessed glandular, capitates mushroom like multicellular trichomes covered with tubercle papicles. Rounded, oval, triangular shaped oil droplets were observed in some species. It is concluded that qualitative and qualitative anatomical variations in trichomes, stomata and epidermal cells are of good taxonomic value for the Asteroideae species.

The Influence of Light Wavelength on Growth and Antioxidant Capacity in Pachyrhizus erosus (L.) Urban

Pachyrhizus erosus is a plant that is traditionally used in Asia as a food and herbal medicine. This study examined the impact of light-emitting diodes (LEDs), light-emitting plasma (LEP), and fluorescent lamps (FLs) on the growth, antioxidant properties, and phenolic metabolites of P. erosus. Phenolic compound concentration and composition were determined by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) system. Radical scavenging activity was measured using stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. P. erosus antioxidant activity and phenolic compound composition were improved by the application of LEDs and LEP. Blue LED light also produced significantly higher DPPH radical scavenging activity and ABTS values than the other LED and fluorescent light treatments. In P. erosus seedlings, dry weight, fresh weight, plant height, leaf area, and chlorophyll content were greater under blue LED than under FL light. Furthermore, growth under the blue LED enhanced the epidermal cell length, epidermal cell width, and number of stomata. Antioxidant activity and total phenolic and total flavonoid contents positively correlated in the P. erosus grown under blue LED light condition. Among LED treatments, blue LED produced higher total phenolic compounds, dominated by malonyl daidzin and l-phenylalanine. DPPH assay was highly and significantly correlated with vitexin, salicylic acid, p-coumaric acid, p-hydroxybenzoic acid, l-phenylalanine, daidzein, and daidzin. The present study demonstrated that changes in the growth pattern, antioxidant activity, composition, and metabolite concentration occurred in response to light of different wavelengths in P. erosus seedlings. Thus, LED exposure has the potential to enhance the growth characteristics, metabolite accumulation, and antioxidant properties of P. erosus.

Foliar anatomical study of <i>Thaumatococcus daniellii</i> (Benth.) Benth. and <i>Megaphrynium macrostachyum</i> (Benth) Milne-Redh. in Ile-Ife and Osogbo environs, Osun State, Nigeria

Foliar, petiole and stem anatomical characters of Thaumatococcus daniellii and Megaphrynium macrostachyum in Ile-Ife and Osogbo, environs, Osun State in Nigeria are reported. The aim is to determine the macro and micro-characters that could facilitate their identification and classification. It is envisaged that this will further enhance the conservation of the two species and prevent them from extinction. Transverse sections of the leaf, petiole and stem were undertaken using Reichert Sledge Microtome (RSM) and observations were made using Light Microscope (LM). Diagnostic characters employable for their delimitation are their habits, stomata type, length and width of stomata, length and width of epidermal cells, anticlinal walls and stomata index on the abaxial surfaces. Others are air spaces, presence of tannins and sand crystals, abundance of sclerenchyma cells and thick cuticle in M. macrostachyum , presence of crystals of calcium oxalate and carbonate in M. macrostachyum . However, intergeneric characters between the two genera were also reported. Over all, additional diagnostic characters which have not been used for the delimitation of the two species have been reported. All these are envisaged to remove the confusion in their taxonomy and aid their conservation even when only sterile samples are available. © 2017 International Formulae Group. All rights reserved. Keywords: Leaf, petiole, stem, anatomy, diagnostic, conservation

Vertical leaf mass per area gradient of mature sugar maple reflects both height-driven increases in vascular tissue and light-driven increases in palisade layer thickness.

A key trait used in canopy and ecosystem function modeling, leaf mass per area (LMA), is influenced by changes in both leaf thickness and leaf density (LMA = Thickness × Density). In tall trees, LMA is understood to increase with height through two primary mechanisms: (i) increasing palisade layer thickness (and thus leaf thickness) in response to light and/or (ii) reduced cell expansion and intercellular air space in response to hydrostatic constraints, leading to increased leaf density. Our objective was to investigate within-canopy gradients in leaf anatomical traits in order to understand environmental factors that influence leaf morphology in a sugar maple (Acer saccharum Marshall) forest canopy. We teased apart the effects of light and height on anatomical traits by sampling at exposed and closed canopies that had different light conditions at similar heights. As expected, palisade layer thickness responded strongly to cumulative light exposure. Mesophyll porosity, however, was weakly and negatively correlated with light and height (i.e., hydrostatic gradients). Reduced mesophyll porosity was not likely caused by limitations on cell expansion; in fact, epidermal cell width increased with height. Palisade layer thickness was better related to LMA, leaf density and leaf thickness than was mesophyll porosity. Vein diameter and fraction of vascular tissue also increased with height and LMA, density and thickness, revealing that greater investment in vascular and support tissue may be a third mechanism for increased LMA with height. Overall, decreasing mesophyll porosity with height was likely due to palisade cells expanding into the available air space and also greater investments in vascular and support tissue, rather than a reduction of cell expansion due to hydrostatic constraints. Our results provide evidence that light influences both palisade layer thickness and mesophyll porosity and indicate that hydrostatic gradients influence leaf vascular and support tissues in mature Acer saccharum trees.

A dominant-negative actin mutation alters corolla tube width and pollinator visitation in Mimulus lewisii.

A third of all angiosperm species produce flowers with petals fused into a corolla tube. The various elaborations of corolla tube attributes, such as length, width and curvature, have enabled plants to exploit many specialized pollinator groups. These elaborations often differ dramatically among closely related species, contributing to pollinator shift and pollinator-mediated reproductive isolation and speciation. However, very little is known about the genetic and developmental control of these corolla tube attributes. Here we report the characterization of a semi-dominant mutant in the monkeyflower species Mimulus lewisii, with a substantial decrease in corolla tube width but no change in tube length. This morphological alteration leads to a ˜70% decrease in bumblebee visitation rate for the homozygous mutant compared to the wild-type. Through bulk segregant analysis and transgenic experiment, we show that the mutant phenotype is caused by a dominant-negative mutation in an actin gene. This mutation decreases epidermal cell width but not length, and probably also reduces the number of lateral cell divisions. These results suggest a surprising potential role for a 'housekeeping' gene in fine-tuning the development of an ecologically important floral trait.

Genotypic differences in sweet cherries are associated with the susceptibility to mechanical damage

The rheological properties and structure of the flesh tissue at harvest-ripe fruit of the sweet cherry Prunus avium L. cultivars Bing, Lapins, Regina, Santina, Sweetheart and Van were measured using a textural analyzer equipment and described by light microscopy, respectively. The rheological measurements inflicted reproducible levels of mechanical damage (pitting). The structural and rheological properties of the mesocarp and epidermis correlate with their susceptibility to mechanical damage. Epidermal cell width and area of external mesocarp cells were negatively associated with susceptibility to mechanical damage while cell number, quantified in 1mm2 of external mesocarp, was positively associated. Fruit of Bing and Regina are the least susceptible to mechanical damage among the cultivars under study. The least sensitivity of Regina fruit was associated with its wide epidermal cells and high value of modulus of elasticity, while in Bing with its low number of cells as well as high values of stress and strain at bioyield point. The high susceptibility to mechanical damage of Sweetheart and Lapins fruit was associated with their large number of cells in the external mesocarp tissue and with the lowest values of strain at bioyield point, therefore with the lowest deformation capacity of the tissue.

Foliar micro-morphology of Gasteria bicolor haw. (Asphodelaceae) from South Africa.

The succulent genus, Gasteria, which comprises 16 species, is endemic to South Africa and has its main centre of distribution in the Savanna Region of the Eastern Cape. Whereas G. bicolor has been investigated phyto-chemically and pharmacologically, not much data concerning the anatomical and micro-morphological features can be found in literature. This study was undertaken, using light and scanning electron microscopy to obtain information on the micro-morphological features of this important medicinal plant to facilitate its identification and authentication. The elemental composition of the leaf was determined by energy dispersive X-ray spectroscopy (EDXS). The epidermal cells are either hexagonal or pentagonal in form, and are compactly arranged with undulate anti-clinal cell walls. The epidermal cell width was approximately 50 µm. Stomata apertures are elliptical and the upper epidermis of the leaf has paracytic stomata which are slightly raised above the epidermal surface with 4 to 5 subsidiary cells surrounding each stoma. Based on the EDXS microanalysis, the mineral crystals present at the level of the mesophyll of G. bicolor were probably mixtures of calcium oxalate, calcium sulphate and silica. The co-occurrence of aluminum suggests the potential role of the crystals in detoxification of aluminum and heavy metals, as reported previously.

Morphological and anatomical relationships in Alpine-Dinaric populations of the genus Iris L., Pallidae series (A. Kern.) Trinajstić (Iridaceae)

The relationships within the <em>Alpine-Dinaric</em> and cultivated populations of the genus <em>Iris</em>, <em>Pallidae</em> series, have been analysed. Seven morphological characteristics (stem length, length of the largest leaf, greatest width of the largest leaf, length of the smallest leaf, greatest width of the smallest leaf, the number of leaves and the number of flowers) and seven leaf anatomical (length and width of stomata, length and width of epidermal cells, number of stomata and epidermal cells per mm'- and length of styloids) have been used for this purpose. Relationships between populations were analysed by methods of multivariate statistics (Cluster, PCA and MST analyses). The results of Cluster and PCA analyses showed that, owing to leaf anatomical features, five main groups of the populations could be distinguished within the <em>Pallidae</em> series. Four of them belong to the species <em>L. pallida</em>, <em>L. cengialti</em>, <em>L. illyrica</em> and <em>I. pseudopallida</em>. The MST analyses showed that the fifth group contained mixed populations of <em>I. illyrica</em> and <em>I. pseudopallida</em>. The results point at the lack of taxonomic usefulness of the leaf anatomical features analysed and indicate that they caused successive geographical differentiation of the populations of the <em>Pallidae</em> series.

Comparative foliar anatomical and morphological studies of <i>Nephrolepis biserrata</i> (swartz) Scott and <i>N. undulata</i> (Swartz) J.Sm. in Nigeria

The foliar anatomy and morphology of Nephrolepis biserrata and Nephrolepis undulata were investigated. The aim of which is to elucidate their taxonomic knowledge with the use of both foliar anatomical and morphological characteristics that exist between them. The anatomicalstudies carried out include shape and size of the epidermal cell, venation patterns, stomata type and distribution. One way analysis of variance was used to show whether the two taxa are significantly different. The results of anatomical similarities in the adaxial surfaces of their leaflets were sinuous, anticlinal walls, absence of stomata and trichome, epidermal cells are irregular in shape and variable in sizes. On their abaxial surfaces, epidermal cells are irregular in shapes and variable in sizes, stomata present, predominantly diacytic and anomocytic types with ellipticshapes, thin and wavy anticlinal wall. Anatomical differences include length and width of epidermal cells, absence or presence and distribution of crystal sands, thickness of anticlinal walls on the adaxial surfaces, stomata Index and frequency, length and breadth of guard cell and guard cell area. The venation patterns showed that the mid-rib is sheathed with parenchyma cells and trichome types were observed in N. biserrata but absent in N. undulata. The distinguishing characters of the two taxa studied are of taxonomic value and can be used to identify and delimit each species and thus widen the scope of their taxonomic knowledge.

Dissecting a wheat QTL for yield present in a range of environments: from the QTL to candidate genes

Previous studies with 95 bread wheat doubled haploid lines (DHLs) from the cross Chinese Spring (CS)xSQ1 trialled over 24 yearxtreatmentxlocations identified major yield quantitative trait loci (QTLs) in homoeologous locations on 7AL and 7BL, expressed mainly under stressed and non-stressed conditions, respectively. SQ1 and CS contributed alleles increasing yield on 7AL and 7BL, respectively. The yield component most strongly associated with these QTLs was grains per ear. Additional results which focus on the 7AL yield QTL are presented here. Trials monitoring agronomic, morphological, physiological, and anatomical traits revealed that the 7AL yield QTL was not associated with differences in flowering time or plant height, but with significant differences in biomass at maturity and anthesis, biomass per tiller, and biomass during tillering. In some trials, flag leaf chlorophyll content and leaf width at tillering were also associated with the QTL. Thus, it is likely that the yield gene(s) on 7AL affects plant productivity. Near-isogenic lines (NILs) for the 7AL yield QTL with CS or SQ1 alleles in an SQ1 background showed the SQ1 allele to be associated with >20% higher yield per ear, significantly higher flag leaf chlorophyll content, and wider flag leaves. Epidermal cell width and distance between leaf vascular bundles did not differ significantly between NILs, so the yield-associated gene may influence the number of cell files across the leaf through effects on cell division. Interestingly, comparative mapping with rice identified AINTEGUMENTA and G-protein subunit genes affecting lateral cell division at locations homologous to the wheat 7AL yield QTL.

The relationship between water availability and anatomical characters in Carex hirta

The effects of edaphic moisture in anatomical characters were evaluated in two different populations of Carex hirta L. with three watering treatment for 6 months to evaluate stability, and determined taxonomic value. Water availability increased ( p < 0.001) leaf thickness from 239 to 289 μm, metaxylem vessel diameter from 17 to 23 μm, air cavity size from 10 to 24% and adaxial epidermal cell height from 18 to 34 μm, and abaxial from 11 to 16 μm, adaxial epidermal cell length from 54 to 105 μm, and abaxial from 35 to 86 μm, and adaxial epidermal cell width from 20 to 33 μm, and abaxial from 15 to 23 μm. Stomatal index and the number of cells in the girder of sclerenchyma did not vary with water availability, hence these traits have taxonomic value. Other characters (the length and amplitude of wall undulations in the epidermal cells, the number of bulliform cells) have a doubtful relation with water availability, because they are variable even in constant homogeneous conditions.

Water Stress Induced Changes in Anatomy of Tomato Leaf Epidermes

Anatomical changes of leaf epidermes of tomato plants (Lycopersicon esculentum Mill. cv. INCA 9) submitted to water stress in the preflowering stage were studied. 20 d after germination, plants were subjected to three treatments: 1) 100 % of evapotranspired water was applied every day, 2) from 100 up to 10 % of evapotranspired water was applied every day, and 3) water supply was completely suppressed. Trichome density was similar in apical, middle and basal zones, and adaxial and abaxial leaf surfaces. Stomatal density and length, and epidermal cell length and width had similar values on the same leaf surface, but the values were higher on the abaxial than on the adaxial leaf surface. The water deficit had little effect on number of trichomes, length and width of epidermal cells and length of stomata, and decreased the stomatal density especially on adaxial surface.

Genetic variation in leaf epidermal cell size and shape in Lolium perenne

Six diploid perennial ryegrass populations, two diploid F1 hybrid families and the autotetraploid cv. Tove were grown in a glasshouse and the mean length and mean width of epidermal cells on the abaxial leaf surface of young fully expanded leaves compared. The diploids varied in cell length by 26%, in cell width by 9% and in length: width ratio by 39%. The cells of cv. Tove were 25% longer and 12% wider than those of the highest ranking diploid and the length: width ratio 9% higher. The DNA contents per telophase root-tip cell nucleus of a large-celled and a small-celled diploid population were similar, suggesting that the variation in epidermal cell size among diploids was due to the action of specific genes and not to differences in genome size. The mean epidermal cell dimensions of four of the above populations growing as plots in a field trial employing three levels of fertiliser nitrogen and four harvesting frequencies were measured on three occasions. Varietal ranking in cell dimensions was consistent over the different managements and dates, and agreed well with the glasshouse results. The results indicate that measurements of leaf epidermal cell length and width can be useful aids both in breeding for herbage yield and in distinguishing varieties with similar flowering dates.

Culm anatomy in barley (Hordeum vulgare)

Four barley varieties and four F8 lines derived by divergent selection for culm length were studied for a number of anatomical characteristics of the culm. Significant differences were observed in length and width of epidermal cells, culm thickness, thickness of sclerenchyma, and thickness of sclerenchyma cell walls. Except for the thickness of the sclerenchyma cell walls, the differences in the anatomical characteristics of the culm were not correlated with those in culm length caused by selection. Although it was not possible to determine the genetic basis of the association between culm length and thickness of the sclerenchyma cell walls because of the type of material used, this result does have implications in relation to breeding for lodging resistance. It is suggested that a higher lodging resistance could be obtained by combining in the same genotype a short culm with thick-walled sclerenchyma cells.

THE ABPHYL SYNDROME IN ZEA MAYS. I. ARRANGEMENT. NUMBER AND SIZE OF LEAVES

A range of phyllotactic variation in Zea mays has been obtained from progeny derived from a single ‘opposite‐leaved’ plant. Some segregants exhibit a form of alternate phyllotaxy with poor separation between nodes, while others duplicate the original decussate condition. Numerous intermediate examples have also been observed. Some have both spiral and opposite arrangements on the same plant; others, which begin their ontogeny with the normal distichous arrangement, switch at different stages of maturity to spiral or decussate arrangement. Leaves from ABPHYL plants are up to one‐half the width of comparable normal leaves although their length is similar. Since ABPHYL plants may have twice as many leaves as do normal siblings, total area and dry weight of leaf blades per ABPHYL plant are greater than in normal siblings. Leaf width of both ABPHYL and normal plants correlates well with the number rather than the width of epidermal cells.