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.


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 and the behaviour of the urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii

Photo credit: Google

Populus purdomii


Infection Behaviour of Melampsora larici-populina on the Leaf Surface of Populus purdomii

by Yu Z.-d., Peng S.-b., Ren Z._z., Wang D.-m., Cao Z.-m. (2011)

Zhong-dong YUShao-bing PENGZheng-zheng RENDong-mei WANGZhi-min CAO

Zhong-dong YU, Forestry College, Northwest A&F University, Jangling, 712100, P.R. China


in Agricultural Sciences in China 10(10): 1562-1569 – DOI10.1016/S1671-2927(11)60152-1 –


Behaviour of urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii were studied by light microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and fluorescence microscope.

Crab-like fusion cells on leaf surface, intercellular hyphal cells in leaf tissues, as well as nucleus states, were observed and counted up in this study. Under unsaturated humidity, 32% of germinated tubes fused into a distinguishable swollen crab-shaped cell at the merging site, and 10.5% of observed crab-like cells had more than three nuclei.

Wedge-shaped mycelia developed and then penetrated the leaf surface directly, or indirectly through stomata. Tips of germtube passed through the intercellular cells of poplar leaves directly were found in TEM. Aniline blue dyeing also showed that the infecting hyphae could invade into the cuticle and epidemic cell wall directly.

For the case of infection through stomata, there were two different situations. Short branches and wedge hyphae usually penetrated the leaf surface via opened stomata, whereas, some germtube branches and wedge hyphae penetrated leaves through the guard cell walls or stoma lips. In the latter case, the stomata were always closed.

The samples from wild forestlands had the same fused cells and wedge hyphae, but the occurrence rate was much higher than that in the chamber. Even under the saturated air humidity, germtubes could roll back and formed fusion structure, or merged together with their tips. The fusion cells might centralize the plasma of merged germtubes and have a strong survival capacity to protect germtubes from dying under arid circumstances, and provide a chance of genetic variation as well.

ABA inhibits entry into stomatal-lineage development



ABA inhibits entry into stomatal-lineage development in Arabidopsis leaves

by Tanaka Y., Nose T., Jikumaru Y., Kamiya Y. (2013)

Yoko TanakaTomoe NoseYusuke JikumaruYuji Kamiya

Yoko Tanaka, RIKEN Plant Science Center

Yusuke Jikumaru, RIKEN Plant Science Center, Department of Biosciences, Teikyo University


in Plant Journal 74(3): 448457 – DOI10.1111/tpj.12136


The number and density of stomata are controlled by endogenous and environmental factors. Despite recent advances in our understanding of stomatal development, mechanisms which prevent stomatal‐lineage entry remain unclear.

Here, we propose that abscisic acid (ABA), a phytohormone known to induce stomatal closure, limits initiation of stomatal development and induces enlargement of pavement cells in Arabidopsis cotyledons.

An ABA‐deficient aba2‐2 mutant had an increased number/proportion of stomata within a smaller cotyledon, as well as reduced expansion of pavement cells. This tendency was reversed after ABA application or in an ABA over‐accumulatingcyp707a1cyp707a3 doublemutant.

Our time course analysis revealed that aba2‐2 shows prolonged formation of meristemoids and guard mother cells, both precursors of stoma. This finding is in accordance with prolonged gene expression of SPCH and MUTE, master regulators for stomatal formation, indicating that ABA acts upstream of these genes.

Only aba2‐2 mute, but not aba2‐2 spch double mutant showed additive phenotypes and displayed inhibition of pavement cell enlargement with increased meristemoid number, indicating that ABA action on pavement cell expansion requires the presence of stomatal‐lineage cells.