scholarly journals Differential shrinkage of mesophyll cells in transpiring cotton leaves: implications for static and dynamic pools of water, and for water transport pathways

2012 ◽  
Vol 39 (2) ◽  
pp. 91 ◽  
Author(s):  
Martin Canny ◽  
Suan Chin Wong ◽  
Cheng Huang ◽  
Celia Miller
Keyword(s):  
Gossypium Hirsutum L ◽  
Mesophyll Cells ◽  
Transport Pathways ◽  
Spongy Mesophyll ◽  
Structural Rigidity ◽  
Relative Water ◽  
Differential Shrinkage ◽  
Palisade Cells ◽  
Leaf Volume ◽  
Scanning Electron

Shrinkage of palisade cells during transpiration, previously measured for sclerophyllous leaves of Eucalyptus where cells shrank equally, was compared with shrinkage in thin mesophytic leaves of cotton (Gossypium hirsutum L.). Selected vapour pressure differences (Δe) from 0.6 to 2.7 kPa were imposed during steady-state photosynthesis and transpiration. Leaves were then cryo-fixed and cryo-planed paradermally, and images obtained with a cryo-scanning electron microscope (CSEM). Diameters of palisade ‘cavity cells’ within sub-stomatal cavities, and surrounding palisade ‘matrix cells’ were measured on CSEM images. Cavity and spongy mesophyll cells shrank progressively down to Δe = 2.7 kPa, while matrix cells remained at the same diameter at all Δe. Diameters were also measured of cavity and matrix cells quasi-equilibrated with relative humidities (RHs) from 100% to 86%. In leaves quasi-equilibrated with 95% RH, the cavity cells shrank so much as to be almost unmeasurable, while matrix cells shrank by only 6%. These data suggest that there are two distinct pools of water in cotton leaves: cavity plus spongy mesophyll cells (two-thirds of leaf volume) which easily lose water; and matrix cells (one-third of leaf volume), which retain turgor down to relative water loss = 0.4, providing structural rigidity to prevent wilting. This phenomenon is probably widespread among mesophytic leaves.

scholarly journals Maximum CO 2 diffusion inside leaves is limited by the scaling of cell size and genome size

2021 ◽  
Vol 288 (1945) ◽  
pp. 20203145
Author(s):  
Guillaume Théroux-Rancourt ◽  
Adam B. Roddy ◽  
J. Mason Earles ◽  
Matthew E. Gilbert ◽  
Maciej A. Zwieniecki ◽  
...  
Keyword(s):  
Genome Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Phase Diffusion ◽  
Leaf Mesophyll ◽  
Leaf Tissues ◽  
Mesophyll Surface Area ◽  
Leaf Volume

Maintaining high rates of photosynthesis in leaves requires efficient movement of CO 2 from the atmosphere to the mesophyll cells inside the leaf where CO 2 is converted into sugar. CO 2 diffusion inside the leaf depends directly on the structure of the mesophyll cells and their surrounding airspace, which have been difficult to characterize because of their inherently three-dimensional organization. Yet faster CO 2 diffusion inside the leaf was probably critical in elevating rates of photosynthesis that occurred among angiosperm lineages. Here we characterize the three-dimensional surface area of the leaf mesophyll across vascular plants. We show that genome size determines the sizes and packing densities of cells in all leaf tissues and that smaller cells enable more mesophyll surface area to be packed into the leaf volume, facilitating higher CO 2 diffusion. Measurements and modelling revealed that the spongy mesophyll layer better facilitates gaseous phase diffusion while the palisade mesophyll layer better facilitates liquid-phase diffusion. Our results demonstrate that genome downsizing among the angiosperms was critical to restructuring the entire pathway of CO 2 diffusion into and through the leaf, maintaining high rates of CO 2 supply to the leaf mesophyll despite declining atmospheric CO 2 levels during the Cretaceous.

An analysis of the effects of gibberellic acid on the leaflet structure of dwarf cultivars of pea (Pisum sativum)

1979 ◽  
Vol 57 (10) ◽  
pp. 1089-1092 ◽  
Author(s):  
G. F. Israelstam ◽  
Erica Davis
Keyword(s):  
Pisum Sativum ◽  
Gibberellic Acid ◽  
Surface Area ◽  
Epidermal Cells ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Number Of Layers ◽  
Dwarf Cultivar ◽  
Palisade Cells ◽  
Degree Of Differentiation

The effects of gibberellic acid (GA3) on the penultimate leaflets of dwarf and normal cultivars of pea were investigated. In control plants, the leaflets of the dwarf were heavier, thicker, and had a smaller surface area than the normal. Epidermal and palisade cells of the dwarf were longer than those of the normal cultivar and the dwarf had longer spongy mesophyll cells and more layers of spongy mesophyll than the normal, with fewer intercellular spaces.Application of GA3 to dwarf plants increased leaflet surface area and length of epidermal cells, while leaflet weight and thickness and the number of layers of spongy mesophyll cells decreased. No significant changes in the leaflet of the normal cultivar were induced by GA3.The overall effect of GA3 application to the dwarf cultivar was to induce a degree of differentiation in the penultimate leaflets such that they tended to resemble more closely those of the normal cultivar.

scholarly journals Ultrastructural and Surface Features of Apple Leaves following White Apple Leafhopper Feeding

HortScience ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 249-251
Author(s):  
Robert M. Welker ◽  
Richard P. Marini ◽  
Douglas G. Pfeiffer
Keyword(s):  
Cell Injury ◽  
Stomatal Density ◽  
Starch Granules ◽  
Feeding Damage ◽  
Abaxial Epidermis ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Transmission Electron ◽  
Feeding Area ◽  
Palisade Cells

White apple leafhopper (WALH; Typhlocyba pomaria McAtee) feeding damage on apple (Malus domestica Borkh.) leaves was examined with scanning and transmission electron microscopy. WALH created feeding holes in the (lower) abaxial epidermis, with no visible exterior evidence of cell injury to the adaxial (upper) epidermis. Feeding holes were located in areas of the leaf with high stomatal density and were near stomata. Groups of cells in the palisade layers were empty or contained coagulated cell contents. Adjacent, apparently noninjured, palisade cells contained an abundance of starch granules, possibly indicating that photoassimilate export was impaired. Spongy mesophyll cells abaxial to the feeding area were left intact as were the epidermal cells adaxial to the feeding area. External views of either epidermis and internal leaf views of injured cells indicated no cell wall collapse.

Electron microprobe analyses of salt distribution in the halophyte Salicornia pacifica var. utahensis

1977 ◽  
Vol 55 (11) ◽  
pp. 1516-1523 ◽  
Author(s):  
D. J. Weber ◽  
H. P. Rasmussen ◽  
W. M. Hess
Keyword(s):  
Electron Microprobe ◽  
High Salt ◽  
Leaf Section ◽  
X Ray ◽  
Salt Ions ◽  
Palisade Cells ◽  
Salt Distribution ◽  
Photosynthetic Cells ◽  
Scanning Electron ◽  
Vascular Region

The halophyte Salicornia pacifica var. utahensis grows in the desert saline playa. The fused leaves form succulent stems and have apparently isolated tracheids in the palisade region as observed by scanning electron microscopy. Frozen shoots were fractured under liquid nitrogen and scanned for Na+, K+, and Cl− with an electron microprobe X-ray analyzer. In young shoots, the palisade cells were low in salts, and the spongy cells had higher concentrations. The salt in the spongy cells provides a high osmotic pressure permitting the plant to absorb more water from the soil. As the shoots matured, the concentration of salts increased in the spongy cells, and the amount of salt in the palisades also increased. The salt ions in the palisades were excluded from the organelles and were mainly present in the vacuoles. Eventually, the leaf section collapsed because of the high salt in the palisade and spongy cells, but the vascular region in the shriveled section continued to function. The sections adjacent to the dead shriveled section remained green and succulent. The salt tolerance appeared to be based on the exclusion of the salt from the photosynthetic cells and on the ability of the succulent stem to function even though sections were dead owing to high salt concentration.

scholarly journals Submicroscopical Features of Leaves of Xyris Species

2001 ◽  
Vol 44 (4) ◽  
pp. 405-410 ◽  
Author(s):  
Maria das Graças Sajo ◽  
Silvia Rodrigues Machado
Keyword(s):  
Electron Microscope ◽  
Cell Walls ◽  
Guard Cells ◽  
Leaf Ultrastructure ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Inner Surface ◽  
Stomatal Guard Cells ◽  
Adaptative Significance ◽  
Scanning Electron

The leaf ultrastructure of five Xyris species were examined using scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical methods. All studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. Such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. Pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. There were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.

scholarly journals A Technique for Precise Inoculation of the Internal Phyllosphere of Cotton with Xanthomonas campestris pv. malvacearum

2003 ◽  
Vol 93 (10) ◽  
pp. 1204-1208 ◽  
Author(s):  
N. Kangatharalingam ◽  
Margaret L. Pierce ◽  
Margaret Essenberg
Keyword(s):  
Xanthomonas Campestris ◽  
Bacterial Population ◽  
Guard Cells ◽  
Distilled Water ◽  
Circular Area ◽  
Phytopathogenic Bacterium ◽  
Spongy Mesophyll ◽  
Adaxial Surface ◽  
Custom Made ◽  
Palisade Cells

A technique was developed to inoculate uniformly and gently the internal phyllosphere from the upper surface of cotton leaves with the phytopathogenic bacterium Xanthomonas campestris pv. malvacearum. The inoculum consisted of 2 to 3 × 107 CFU/ml in CaCO3-saturated sterile distilled water containing 0.02%, vol/vol, of the wetting agent Silwet L-77. A custom-made inoculation apparatus was employed to immerse a circular area of the adaxial surface of a leaf in inoculum for 90 s. This resulted in uniform, passive entry of bacteria into the substomatal chambers, producing an endophytic bacterial population of 2 × 104 CFU/cm2. Microscopic signs of infection were visible 48 to 72 h after inoculation. In susceptible leaves, uniformly distributed water-soaked spots were observed 7 to 8 days after inoculation. When the technique was used on resistant leaves, the autofluorescence that is characteristic of hypersensitively necrotic cells developed in the guard cells and palisade cells lining substomatal chambers, but not in the underlying spongy mesophyll.

scholarly journals xpression of aquaporin subtypes (GhPIP1;1, GhTIP2;1, and GhSIP1;3) in cotton (Gossypium hirsutum L.) submitted to salt stress

AoB Plants ◽  
2019 ◽  
Author(s):  
Luana C C Braz ◽  
Pedro D Fernandes ◽  
Daniela D Barbosa ◽  
Wellison F Dutra ◽  
Carliane R C Silva ◽  
...  
Keyword(s):  
Salt Stress ◽  
Gas Exchange ◽  
Gossypium Hirsutum ◽  
Water Content ◽  
Relative Water Content ◽  
Dry Matter ◽  
Rna Extraction ◽  
Gossypium Hirsutum L ◽  
Relative Water ◽  
Agricultural Regions

Abstract Salinization leads to several worldwide damages in agricultural regions, mainly in semiarid regions where leaching of salt is poor due to limited and erratic rainfall. Cotton (Gossypium hirsutum L.) is a Malvaceae with wide genetic variability to salt stress. The identification of salinity tolerant genotypes is a dynamic target in a breeding program, and the selection is often based on plant phenotypes. Molecular markers are reliable tools to aid in these selection procedures. Aquaporin (AQPs) are channel proteins that play fundamental role in water relations and tolerance to environmental stresses. Plants have fine regulation of water transport through AQPs activities. In order to evaluate the AQP expressions of different cotton cultivars submitted to salt stress, we use molecular and physiological tools, based on RT-qPCR and gas exchange assays. Seven cultivars were submitted to 95 mM NaCl, started at V3 stage (21 days after emergence), during 72 h. At the end of stress treatment, root tissues were used to total RNA extraction, followed by cDNA synthesis and RT-qPCR analyzes. Three sets of specific primers were used, drawn from AQP accessions deposited in NCBI. Additionally, full expanded leaves were used to gas exchange assays and to estimate the relative water content. The dry matter of the shoots was also evaluated. Based on pattern of AQPs transcripts, we found that all semiarid tolerant cultivars (BRS Seridó, 7MH, CNPA MT 2009 152 and BRS 416) showed downregulation of AQP subtypes, mainly GhPIP1;1 and GhTIP2;1 whose action is characterized as tolerant to salinity. The results of gas exchanges, relative water content and dry matter were consistent with the molecular findings in these cultivars, confirming that GhPIP1;1 and GhTIP2;1, located at plasma membrane and vacuoles, respectively, could be adopted as AQP markers for identification of cotton tolerant to salt stress.

Acid rain effects on foliar histology of Artemisia tilesii

1984 ◽  
Vol 62 (3) ◽  
pp. 463-474 ◽  
Author(s):  
C. M. Adams ◽  
N. G. Dengler ◽  
T. C. Hutchinson
Keyword(s):  
Acid Rain ◽  
Fungal Pathogens ◽  
Leaf Tissue ◽  
Epidermal Cells ◽  
Simulated Acid Rain ◽  
Scanning Electron Micrographs ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
Abnormal Cell ◽  
Naturally Occurring

The present study describes the effects of simulated acid rain (pH 2.5–5.6) on foliar histology of an arctic herb, Artemisia tilesii Ledeb., which is remarkably tolerant to naturally occurring atmospheric acidity at Smoking Hills, N.W.T. Plants were exposed to simulated acid rain twice weekly for 4 weeks in exposure chambers in the greenhouse. Droplets as acidic as pH 2.5 caused limited macroscopic foliar damage. However, much greater damage was observed when sectioned leaf tissue was examined microscopically. On leaves having no injury visible to the unaided eye, small lesions consisting of one to three collapsed epidermal cells were observed in scanning electron micrographs and in cleared leaves after exposure to rain of pH 3.0 and 3.5. Stomata remained open in damaged areas of acid-sprayed leaves. Lesions most commonly developed from an initial collapse of a few adaxial epidermal cells, followed by progressive injury of underlying tissues. Palisade and spongy mesophyll cells underwent hypertrophic (abnormal cell enlargement) and hyperplastic (abnormal cell division) responses in the region adjacent to severely collapsed tissue, causing reduced intercellular spaces. These effects isolated the injured areas from adjacent healthy tissues, and resembled wound periderm responses to fungal pathogens and to mechanical irritation. This response may be one mechanism of limiting acid rain damage.

THE INHERITANCE AND HISTOLOGY OF A CHLOROPHYLL-DEFICIENT CHARACTER IN MEDICAGO SATIVA L.

1961 ◽  
Vol 39 (4) ◽  
pp. 847-853 ◽  
Author(s):  
W. R. Childers ◽  
H. A. McLennan
Keyword(s):  
Recessive Gene ◽  
Single Recessive Gene ◽  
Mesophyll Cells ◽  
Genetic Studies ◽  
Continuous Layer ◽  
Mesophyll Tissue ◽  
Plant Stage ◽  
Chlorophyll Production ◽  
Medicago Sativa L ◽  
Palisade Cells

Further support for tetrasomic inheritance in alfalfa was shown from genetic studies of a chlorophyll-deficient seedling character. The character was determined by a single recessive gene for which the symbol Viridis-1 or v1 is proposed. At the mature-plant stage, low and intermediate classes for chlorophyll production were observed. Histological examination and chlorophyll analyses confirmed this classification. The low-chlorophyll-producing class was characterized by a lack of plastids in the leaf blades although some plastids occurred in mesophyll tissue around the midrib. The intermediate chlorophyll-deficient class was characterized by yellowish-green leaf blades, associated with colorless palisade cells that overlay a single continuous layer of mesophyll cells in which the plastids were well developed.

Verticillium wilt of chrysanthemum: quantitative relationship between increased stomatal resistance and local vascular dysfunction preceding wilt

1976 ◽  
Vol 54 (10) ◽  
pp. 1023-1034 ◽  
Author(s):  
William E. MacHardy ◽  
Lloyd V. Busch ◽  
Robert Hall
Keyword(s):  
Water Stress ◽  
Water Transport ◽  
Vascular Dysfunction ◽  
Stomatal Closure ◽  
Quantitative Relationship ◽  
Stomatal Resistance ◽  
Chrysanthemum Morifolium ◽  
Transport Pathways ◽  
Relative Water ◽  
Chrysanthemum Morifolium Ramat

The relationship between the development of water stress and foliar symptom expression within chrysanthemum (Chrysanthemum morifolium Ramat) cuttings infected with Verticillium dahliae Kleb. was examined using relative water content (RWC), diffusive resistance to water vapor loss (stomatal resistance), and dye distribution along water-transport pathways as indicators of water stress. The RWC remained at a normal level until symptoms appeared, but stomatal resistance increased beginning about 8 days before symptoms. Dye movement along xylem elements was uniform within uninoculated checks and also within infected plants until stomatal resistances increased. Veinal dye distribution was incomplete within tissue exhibiting increased stomatal resistances, and the extent of dye interruption was closely aligned to the magnitude of resistance increase. Apparently, stomatal closure effectively prevented tissue desiccation under conditions of high, localized internal water stress, but this mechanism could not prevent tissue from becoming flaccid or wilted when water transport became so limited that water was deficient even within the large veins.

Sign in / Sign up

Export Citation Format

Share Document