Active ingredients of pesticides, growth regulators and chemical inducers with high molecular weights penetrate leaves at higher rates when formulated as ions.



Size selectivity of aqueous pores in stomatous cuticles of Vicia faba leaves

by Schlegel T. K., Schönherr J., Schreiber L. (2006)

Thomas K. SchlegelJörg SchönherrLukas Schreiber

Thomas K. Schlegel,  Jörg Schönherr, University of Hannover, Institute of Vegetable and Fruit Science, Sarstedt, Germany

Lukas Schreiber, University of Bonn, Institute of Cellular and Molecular Botany (IZMB), Bonn, Germany


in Planta 221(5): 648-655 – DOI10.1007/s00425-005-1480-1 –


Size selectivity of aqueous pores in Vicia leaf cuticles was investigated by measuring the penetration of calcium salts into the abaxial surface of detached leaves. Molecular weights of salts ranged from 111 g mol−1 to 755 g mol−1. Penetration in light at 20°C and 100% humidity was a first order process and rate constants of penetration ranged from 0.39 h−1 (CaCl2) to 0.058 h−1 (Ca-lactobionate). Penetration was a first order process in the dark as well, but the rate constants were smaller by a factor of 1.82.

Plotting logarithmatised rate constants versus anhydrous molecular weights resulted in straight lines both in light and in the dark. The slopes per hour were very similar and the average slope was −1.2×10−3 mol g−1. Hence, size selectivity was not affected by stomatal opening, and in light or darkness permeability of Vicia cuticles decreased by a factor of 2.9 when molecular weight increased from 100 g mol−1 to 500 g mol−1.

Silver nitrate was preferentially precipitated as silver chloride in guard cells, glandular trichomes and at the base of trichomes.

It was concluded that these precipitates mark the location of aqueous pores in Vicia leaf cuticles. The size selectivity of aqueous pores in Vicia leaf cuticles is small compared to that observed in poplar leaf cuticles, in which permeability decreased by a factor of 7–13 for the same range of molecular weights. It is also much smaller than size selectivity of the lipophilic pathway in cuticles.

These findings suggest that active ingredients of pesticides, growth regulators and chemical inducers with high molecular weights penetrate leaves at higher rates when formulated as ions.


Stomata in Rhododendron (Ericaceae)

Photo credit: Google

Rhododendron Bushes


Significance of the leaf epidermis fingerprint for taxonomy of Genus Rhododendron

by Wang X.-w, Mao Z.-j., Choi K., Park K.-w. (2006)

Wang Xiu-weiMao Zi-junChoi KyungPark Kwang-woo

Wang Xiu-wei, Mao Zi-jun, Northeast Forestry University, Key Laboratory of Forest Plant Ecology Ministry of Education China, Harbin, P. R. China

Choi Kyung, Park Kwang-woo, Korea Forest Service, National Arboretum, Pochen-Gun, Korea


in Journal of Forestry Research 17(3): 171-176 – DOI10.1007/s11676-006-0041-1 –


Leaf epidermal fingerprints of six species of Rhododendron (Rh. Aureaum, Rh. dauricum, Rh. micranthum, Rh. Mucronulatum, Rh. Redowskianum, Rh. schlippenbachii) were observed by optical microscope with nail polish expression method in Key Laboratory of Forest Plant Ecology of Ministry Education China in Northeast Forestry University in 2004.

The leaf morphological features including of stomata types, characters of guard cells, subsidiary cells in lower epidemis were observed. And ordinary cells (in shape and anticlinal walls feature) as well as the trichomes in both sides of the leaves are described in detail.

The results showed that there were three types of stoma in six investigated Rhododendron species, from which pericytic stomata type exists in three species (Rh. dauricum, Rh. micranthum, and Rh. mucronulatum),

Anomocytic stomatal type in Rh. Redowskianum, diacytic stomata type in Rh. aureaum and Rh. schlippenbachii. The subsidiary cells of the pericytic and diacytic stomata type are different in shape and surface feature between the species, respectively.

The ordinary epidermal cells show a variety from quadrangular to hexagonal, polygonal or irregular in surface view, the anticlinal walls are straight or sinuose. Trichomes (gland scales) are present in the both of the leaf sides in three species (Rh. dauricum, Rh. micranthum, and Rh. mucronulatum).

All of these detail leaf features show specific specificity of leaf fingerprint for 6 rhododendrons.

Impact of irradiance on the stomata of Impatiens

Photo credit:  Google

Impatiens flanaganae


Impact of irradiance on the epidermis of Impatiens flanaganae Hemsl

by Lall N., Bhat R.B. (1996)

in  South African Journal of Botany 62(4): 212-216 – DOI10.1016/S0254-6299(15)30637-2 –


Variations in the epidermis oi Impatiens flanaganae Hemsl. grown under different light conditions were investigated.

The difference in light intensity triggered an extrinsic and intrinsic instability which greatly promoted aberrant stomatal development and variations of epidermal cells.

Four types of normal stomata were observed. The ontogeny of stomata was either perigenous or mesogenous. An increase in stomatal abnormalities was noticed in leaves subjected to greater and lower light intensities than in the control.

Abnormalities such as degeneration of guard cells, superimposed and juxtaposed contiguous stomata, stomata with persistent intervening walls, unequal guard cells, cytoplasmic connections, single guard ceils, guard cells without pores, and persistent stomatal cells were noticed.

The size and shape of epidermal cells, stomatal index, frequency of stomata and epidermal cells were also compared and recorded in different variants.

These results have implications tor the conservation of this endangered species.

RCN1/OsABCG5 is involved in accumulation of ABA in guard cells, indispensable for stomatal closure.



Rice Stomatal Closure Requires Guard Cell Plasma Membrane ATP-Binding Cassette Transporter RCN1/OsABCG5

by Matsuda S., Takano S., Sato M., Furukawa K., Nagasawa H., Yoshikawa S., Kasuga J., Tokuji Y., Yazaki K. , Nakazono M., Takamure I., Kato K. (2016)

Shuichi MatsudaSho TakanoMoeko SatoKaoru FurukawaHidetaka NagasawaShoko YoshikawaJun KasugaYoshihiko TokujiKazufumi YazakiMikio NakazonoItsuro TakamureKiyoaki Kato

in Molecular Plant 9(3): 417-427 – DOI10.1016/j.molp.2015.12.007 –


Water stress is one of the major environmental stresses that affect agricultural production worldwide. Water loss from plants occurs primarily through stomatal pores.

Here, we report that an Oryza sativa half-size ATP-binding cassette (ABC) subfamily G protein, RCN1/OsABCG5, is involved in stomatal closure mediated by phytohormone abscisic acid (ABA) accumulation in guard cells.

We found that the GFP-RCN1/OsABCG5-fusion protein was localized at the plasma membrane in guard cells. The percentage of guard cell pairs containing both ABA and GFP-RCN1/OsABCG5 increased after exogenous ABA treatment, whereas they were co-localized in guard cell pairs regardless of whether exogenous ABA was applied.

ABA application resulted in a smaller increase in the percentage of guard cell pairs containing ABA in rcn1 mutant (A684P) and RCN1-RNAi than in wild-type plants. Furthermore, polyethylene glycol (drought stress)-inducible ABA accumulation in guard cells did not occur in rcn1 mutants.

Stomata closure mediated by exogenous ABA application was strongly reduced in rcn1 mutants. Finally, rcn1 mutant plants had more rapid water loss from detached leaves than the wild-type plants.

These results indicate that in response to drought stress, RCN1/OsABCG5 is involved in accumulation of ABA in guard cells, which is indispensable for stomatal closure.

Stomata in Solidago of Poland

Photo credit Google – Solidago juncea –


Leaf epidermis traits as tools to identify Solidago L. taxa in Poland

by Szymura M., Wolski K. (2011)

in Acta Biologica Cracoviensia. Series Botanica 53: 1 – ISSN :0001-5296 –


We used via light and scanning electron microscopy to study the leaf epidermis of five Solidago taxa from southwestern Poland. Light microscopy was employed to describe the epidermal surface, including stomatal types, the shape of epidermal cell walls, stomatal density, the distribution of stomata between the abaxial and adaxial epidermis, and stomatal guard cell length.

From these observations we calculated the stomatal index (SI) and stomatal ratio (SR) as the basis for defining the type of leaf.

From LM of transverse sections of leaf we described mesophyll structure, the presence of secretory canals, adaxial and abaxial epidermis thickness, and leaf thickness.

We examined cuticular ornamentation, trichome features and epicuticular secretions by SEM.

As determined by discriminatory analysis, the most important traits distinguishing these taxa were the stomatal index of the adaxial epidermis, leaf thickness, features of the walls of epidermal cells, and the presence and features of trichomes.

On the basis of observations and measurements we created a key for distinguishing Solidago taxa.

MUSTACHES enforces stomatal bilateral symmetry



The Arabidopsis leucine-rich repeat receptor-like kinase MUSTACHES enforces stomatal bilateral symmetry in Arabidopsis.

by Keerthisinghe S,   Nadeau J. A., Lucas J. R., Nakagawa T., Sack F. D. (2015)

Sandra KeerthisingheJeannette A. NadeauJessica R. LucasTsuyoshi NakagawaFred D. Sack

Sandra Keerthisinghe, Botany Department, University of British Columbia

Jeannette A. Nadeau, Jessica R. Lucas,, Fred D. Sack, Department of Plant Cellular and Molecular Biology, Ohio State University

Tsuyoshi Nakagawa, Center for Integrated Research in Science, Shimane University


in The Plant Journal 8(5): 684 – 694 – DOI: 10.1111/tpj.12757 –


Stomata display a mirror‐like symmetry that is adaptive for shoot/atmosphere gas exchange. This symmetry includes the facing guard cells around a lens‐shaped and bilaterally symmetric pore, as well as radially arranged microtubule arrays that primarily originate at the pore and then grow outwards.

Mutations in MUSTACHES (MUS), which encodes a leucine‐rich repeat receptor‐like kinase, disrupt this symmetry, resulting in defects ranging from skewed pores and abnormally focused and depolarized radial microtubule arrays, to paired guard cells that face away from each other, or a severe loss of stomatal shape.

Translational MUSproMUS:tripleGFP fusions are expressed in cell plates in most cells types in roots and shoots, and cytokinesis and cell plates are mostly normal in mus mutants.

However, in guard mother cells, which divide and then form stomataMUS expression is notably absent from new cell plates, and instead is peripherally located.

These results are consistent with a role for MUS in enforcing wall building and cytoskeletal polarity at the centre of the developing stoma via signalling from the vicinity of the guard cell membrane.

Stomata in Echium vulgare L. flowers (Boraginaceae)

Photo credit : Google

Viper’s Bugloss, Echium vulgare


Micromorphology of glandular structures in Echium vulgare L. flowers

by Weryszko-Chmielewska E., Chwil M. (2007)

Weryszko-Chmielewska E., Department of Botany, University of Life Sciences, Akademicka 15, 20-950 Lublin, Poland

in Acta Agrobotanica 61: 2 –  ISSN :0065-0951 –