Harmful effects of radicals generated in polluted dew

Harmful effects of radicals generated in polluted dew on the needles of Japanese Red Pine (Pinus densiflora)

by Kume A. (2001)

Atsushi Kume

===

In New Phytologist, 2001 –

https://www.academia.edu/39627231/Harmful_effects_of_radicals_generated_in_polluted_dew_on_the_needles_of_Japanese_Red_Pine_Pinus_densiflora_

Abstract

The effects of free radicals, ·OH and ·NO, generated in polluted dew water on needles of Pinus densiflora (Japanese Red pine) were investigated. • ·OH-generating solutions (HOOH with Fe(III) and oxalate ion; ·OH treatment) and ·OH- and ·NO-generating solutions (NO2−; ·OH/·NO treatment) were regulated at 25, 50 and 100 µmol and pH 4.4. HOOH only (HOOH treatment) was used as a control solution.

Solutions were applied as a mist to the needle surface of P. densiflora seedlings before dawn twice a week for 3 months. • Within a month, net photosynthesis at near saturating irradiance (Pn) and stomatal conductance (gl) of ·OH-treated needles decreased with increasing solution concentration. The HOOH treatment had no effects on any of the measured parameters. Therefore, ·OH in the artificial dews caused the decreases in Pn and gl. In ·OH/·NO-treated needles, gl increased during the experiment, but Pn was unchanged.

In all experiments, the characteristics of PSII were not significantly altered. • Free radicals in polluted dew water have harmful effects on the photosynthesis of P. densiflora and compound effects of ·OH and ·NO are different.

Increasing sucrose supply also increased sugars and starch content and number of stomata and decreased water potential and size of stomata during in vitro growth period

Fig. 2
 Effect of sucrose concentration (0%, 3%, 6% and9%) on the growth of 
 Alocasia amazonica plantlets at 0 daysof acclimatization (a, b) andafter 30 days of acclimatization (c,d). Bar=2 cm

In vitro sucrose concentration affects growth and acclimatization of  Alocasia amazonica plantlets

by Jo E.-A., Tewari R. K., Hahn E.-J., Paek K.-Y. (2009)

Eun-A Jo, Rajesh Kumar Tewari, Eun-Joo Hahn, Kee-Yoeup Paek,

E.-A. Jo – R. K. Tewari – E.-J. Hahn – K.-Y. Paek : Research Center for the Development of Advanced Horticultural Technology, Chungbuk National University, Cheongju 361-763, Republic of Korea

R. K. Tewari : Laboratory of Plant Nutrition, Graduate School of Horticulture,Chiba University, Matsudo 648, Chiba 271-8510, Japan

===

In Plant Cell Tiss Organ Cult (2009) 96: 307–315 – DOI 10.1007/s11240-008-9488-4 –

https://www.academia.edu/39814270/In_vitro_sucrose_concentration_affects_growth_and_acclimatization_of_Alocasia_amazonica_plantlets

Abstract

Plantlets of  Alocasia amazonica were regenerated on the MS medium supplemented with different concentrations (0–9%) of sucrose. An absence of sucrose in the growth medium induced generation of leaves, however, it decreased multiplication. On contrary, sucrose supply of 6% or 9% enhanced multiplication but hampered photoau-totrophic growth (generation of leaves). Increasing sucrose supply also increased sugars and starch content and number of stomata and decreased water potential and size of stomata during in vitro growth period. During ex vitro acclimatization, shoot length, root length, leaf number and root number of  Alocasia plantlets grown with 3% sucrose, were found to be better among the other studied sucrose concentrations.

Under ex vitro acclimatization, number of stomata, contents of various carbohydrates in the leaves were increased but size of stomata decreased with increasing sucrose supply during in vitro growth period. Moreover, water potential of leaves of plantlets, which have been grown with a sucrose concentration other than 3%, was decreased. During in vitro growth, net CO2 assimilation rate (PN), transpiration (E), stomatal conductance (gs) and variable fluorescence to maximum fluorescence ratio (Fv/ Fm) were unaffected, however, during acclimatization these were changed and maximum PN, E, and gs were observed in the plantlets micropropagated with 3% sucrose. Fv/Fm was decreased severely in the plantlets micropropagated with 6% sucrose during acclimatization. Thus a sucrose concentration of 3% in the medium is appeared to be better among studied concentrations for both in vitro growth and ex vitro acclimatization of  A. amazonica plantlets.

Influence of drought upon certain physiologic processes and upon such reactions as stomatal function

Drought resistance in plants and physiological processes.

by Iljin W. S. (1957)

Faculdad de Agronomia, Universidad Central de Venezuela, maracay, Venezuela

In Annual Review of Plant Physiology 8: 257-274 – https://doi.org/10.1146/annurev.pp.08.060157.001353

https://www.annualreviews.org/doi/abs/10.1146/annurev.pp.08.060157.001353

Quantitative trait loci for adaxial and abaxial stomatal frequencies

Identification of quantitative trait loci for adaxial and abaxial stomatal frequencies in Oryza sativa

by Ishimaru K., Shirota K., Higa M., Kawamitsu Y. (2001)

Ken Ishimaru a

Kanako Shirota b

Masae Higa b

Yoshinobu Kawamitsu b

aDepartment of Plant Physiology, National Institute of Agrobiological Resources, Kannondai, 2-1-2, Tsukuba, Ibaraki 305-8602, Japan

bCrop Science Laboratory, University of the Ryukyus, Okinawa 903-0213, Japan

===

In Plant Physiol. Biochem. 39: 173-177 – https://doi.org/10.1016/S0981-9428(00)01232-8

https://www.sciencedirect.com/science/article/abs/pii/S0981942800012328

Abstract

Stomatal frequency is one of the main factors that determine photosynthetic ability and stomatal conductance. However, the genetic basis for stomatal frequency is still poorly understood. The genetic relations between adaxial and abaxial stomatal frequencies have been studied in rice (Oryza sativa L.) with quantitative trait loci (QTL) analysis approach on a population of backcross inbred lines of japonica Nipponbare × indica Kasalath. Four QTLs controlling adaxial and abaxial stomatal frequencies were identified. On chromosome 3 of rice, QTL for adaxial stomatal frequency overlapped that for abaxial stomatal frequency. There was a high correlation (r = 0.660, P < 0.01) between them, and the allele that increases the expression was contributed by Kasalath for both traits. These results suggest that the same gene may pleiotropically control the stomatal frequency on both surfaces of the leaf. QTLs for leaf rolling related to osmotic stress were also mapped. The absence of overlap in QTLs for leaf rolling and stomatal frequency suggests that osmotic tolerance is at least partly independent of stomatal frequency. The genetic relationship between stomatal frequency and yield is also discussed.

Permeation of Ca2+ through K+ channels in the plasma membrane of stomatal guard cells

Permeation of Ca2+ through K+ channels in the plasma membrane of Vicia faba guard cells

by Fairley-Grenot K. A., Assmann S. M. (1992)

Harvard Biological Laboratories Cambridge, USA

In J. Membr. Biol. 128: 103–113 – https://doi.org/10.1007/BF00231883

https://link.springer.com/article/10.1007/BF00231883#citeas

Abstract

The whole-cell patch-clamp method has been used to measure Ca2+ influx through otherwise K+-selective channels in the plasma membrane surrounding protoplasts from guard cells of Vicia faba. These channels are activated by membrane hyperpolarization. The resulting K+ influx contributes to the increase in guard cell turgor which causes stomatal opening during the regulation of leaf-air gas exchange. We find that after opening the K+ channels by hyperpolarization, depolarization of the membrane results in tail current at voltages where there is no electrochemical force to drive K+ inward through the channels. Tail current remains when the reversal potential for permeant ions other than Ca2+ is more negative than or equal to the K+ equilibrium potential (−47 mV), indicating that the current is due to Ca2+ influx through the K+ channels prior to their closure. Decreasing internal [Ca2+] (Ca i ) from 200 to 2 nm or increasing the external [Ca2+] (Ca o ) from 1 to 10 mm increases the amplitude of tail current and shifts the observed reversal potential to more positive values. Such increases in the electrochemical force driving Ca2+ influx also decrease the amplitude of time-activated current, indicating that Ca2+ permeation is slower than K+ permeation, and so causes a partial block. Increasing Ca o also (i) causes a positive shift in the voltage dependence of current, presumably by decreasing the membrane surface potential, and (ii) results in a U-shaped current-voltage relationship with peak inward current ca. −160 mV, indicating that the Ca2− block is voltage dependent and suggesting that the cation binding site is within the electric field of the membrane. K+ channels in Zea mays guard cells also appear to have a Ca i -, and Ca o -dependent ability to mediate Ca2+ influx. We suggest that the inwardly rectiying K+ channels are part of a regulatory mechanism for Ca i . Changes in Ca o and (associated) changes in Ca i regulate a variety of intracellular processes and ion fluxes, including the K+ and anion fluxes associated with stomatal aperture change.

Reversible inactivation of K+ channels of stomatal guard cells

Reversible inactivation of K+ channels of Vicia stomatal guard cells following the photolysis of caged inositol 1,4,54risphosphate

by Blatt M. R., Thiel G., Trentham D. R. (1990)

Michael R. BlattGerhard ThielDavid R. Trentham

  1. Botany School, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
    • Michael R. Blatt
    •  & Gerhard Thiel
  2. National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK
    • David R. Trentham
  3. Department of Biochemistry and Biological Sciences, University of London, Wye College, Wye (Ashford), Kent, TN25 5AH, UK
    • Michael R. Blatt

===

In Nature 346: 766-769 – doi:10.1038/346766a0 –

https://www.nature.com/articles/346766a0#citeas

Abstract

RECENT investigations suggest that cytoplasmic D-myo-inositol 1,4,5-trisphosphate (InsP3) functions as a second messenger in plants, as in animals, coupling environmental and other stimuli to intracellular Ca2+ release1,2. Cytoplasmic levels of InsP3 and the turnover of several probable precursors in plants are affected by physiological stimuli—including light, osmotic stress and the phytohormone indoleacetic acid3–5—and InsP3 activates Ca2+ channels6 and Ca2+ flux across plant vacuolar7 and microsomal membranes8. Complementary data also link changes in cytoplasmic free Ca2+ to several physiological responses, notably in guard cells which regulate gas exchange through the stomatal pores of higher plant leaves. Recent evidence indicates that guard cell K+ channels and, hence, K+ flux for stomatal movements9 may be controlled by cytoplasmic Ca2+ (ref. 10). So far, however, direct evidence of a role for InsP3 in signalling in plants has remained elusive. Here we report that InsP3 released from an inactive, photolabile precursor, the P5-l-(2-nitrophenyl)ethyl ester of InsP3 (caged InsP3)11 reversibly inactivates K+ channels thought to mediate K+ uptake by guard cells from Vicia faba L. while simultaneously activating an apparently time-independent, inward current to depolarize the membrane potential and promote K+ efflux through a second class of K+ channels12,13. The data are consistent with a transient rise in cytoplasmic free Ca2+ (ref. 9) and demonstrate that intact guard cells are competent to use InsP3 in signal cascades controlling ion flux through K+ channels.

K’-channel activation and deactivation in stomatal guard cells

Comparison of K’-channel activation and deactivation in guard cells from dicotyledon (Vicia faba L.) and a graminaceous monocotyledon (Zea mays)

by Fairley-Grenot K. A., Assmann S. M. (1993)

Harvard Biological Laboratories – Cambridge – USA

In Planta 189: 410-419 – https://doi.org/10.1007/BF00194439

https://link.springer.com/article/10.1007/BF00194439#citeas

Abstract

We describe and compare inward and outward whole-cell K+ currents across the plasma membrane surrounding guard-cell protoplasts from the dicotyledon, Vicia faba, and the graminaceous monocotyledon, Zea mays. Macrosopic whole-cell current is considered in terms of microscopic single-channel activity, which involves discrete steps between conducting (open) and nonconducting (closed) states of the channel protein. Kinetic equations are used to model the number of open and closed states for channels conducting K+ influx (K(in)) and K+ efflux (K(out)) in the two species, and to calculate the rate at which open-closed transitions occur. The opening and closure of K(in) channels in both Vicia and Zea follow single-exponential timecourses, indicating that K(in)-channel proteins in each species simply fluctuate between one open and one closed state. In both species, opening of K(in) channels is voltage-independent, but closure of K(in) channels is faster at more positive membrane potentials. In response to identical voltage stimuli, K(in) channels in Zea open and close approximately three times as fast as in Vicia. In contrast to K(in), K(out) channels in Zea open and close more slowly than in Vicia. The closure of K(out) channels follows a single-exponential timecourse in each species, indicating one open state. The kinetics of K(out)-channel opening are more complicated and indicate the presence of at least two (Vicia) or three (Zea) closed states.