Dependence of the rate-limiting steps in the dark-to-light transition of photosystem II on the lipidic environment of the reaction center

M. MAGYAR, P. AKHTAR, G. SIPKA, W. HAN, X. LI, G. HAN, J.-R. SHEN, P.H. LAMBREV, G. GARAB

Photosynthetica 2022, 60(1):147-156 | DOI: 10.32615/ps.2022.016  

In our earlier works, we have identified rate-limiting steps in the dark-to-light transition of PSII. By measuring chlorophyll a fluorescence transients elicited by single-turnover saturating flashes (STSFs) we have shown that in diuron-treated samples an STSF generates only F₁ (< F_m) fluorescence level, and to produce the maximum (F_m) level, additional excitations are required, which, however, can only be effective if sufficiently long Δτ waiting times are allowed between the excitations. Biological variations in the half-rise time (Δτ_1/2) of the fluorescence increment...

Limiting steps and the contribution of alternative electron flow pathways in the recovery of the photosynthetic functions after freezing-induced desiccation of Haberlea rhodopensis

K. GEORGIEVA, A.V. POPOVA, G. MIHAILOVA, A.G. IVANOV, M. VELITCHKOVA

Photosynthetica 2022, 60(1):136-146 | DOI: 10.32615/ps.2022.008  

Haberlea rhodopensis Friv. is unique with its ability to survive desiccation to an air-dry state during periods of extreme drought and freezing temperatures. To understand its survival strategies, it is important to examine the protective mechanisms not only during desiccation but also during rehydration. We investigated the involvement of alternative cyclic electron pathways during the recovery of photosynthetic functions after freezing-induced desiccation. Using electron transport inhibitors, the role of PGR5-dependent and NDH-dependent PSI-cyclic electron flows and plastid terminal oxidase were assessed during rehydration of desiccated leaves. Recovery...

Photosystem II in bio-photovoltaic devices

R.A. VOLOSHIN, S.M. SHUMILOVA, E.V. ZADNEPROVSKAYA, S.K. ZHARMUKHAMEDOV, S. ALWASEL, H.J.M. HOU, S.I. ALLAKHVERDIEV

Photosynthetica 2022, 60(1):121-135 | DOI: 10.32615/ps.2022.010  

Hybrid photoelectrodes containing biological pigment-protein complexes can be used for environmentally friendly solar energy conversion, herbicide detection, and other applications. The total number of scientific publications on hybrid bio-based devices has grown rapidly over the past decades. Particular attention is paid to the integration of the complexes of PSII into photoelectrochemical devices. A notable feature of these complexes from a practical point of view is their ability to obtain electrons from abundant water. The utilization or imitation of the PSII functionality seems promising for all of the following: generating photoelectricity, photo-producing...

Photosynthetic response of lutein-deficient mutant lut2 of Arabidopsis thaliana to low temperature at high light

A.V. POPOVA, R. VLADKOVA, P. BORISOVA, K. GEORGIEVA, G. MIHAILOVA, V. VELIKOVA, T. TSONEV, A.G. IVANOV

Photosynthetica 2022, 60(1):110-120 | DOI: 10.32615/ps.2022.009  

Alterations in photosynthetic performance of lutein-deficient mutant lut2 and wild type (wt) of Arabidopsis thaliana were followed after treatment with low temperature and high light for 6 d. The obtained results indicated lower electrolyte leakage, lower excitation pressure, and higher actual photochemical efficiency of PSII in lut2 plants exposed to combined stress compared to wt plants. This implies that lut2 is less susceptible to the applied stress conditions. The observed lower values of quantum efficiency of nonphotochemical quenching and energy-dependent component of nonphotochemical quenching in lut2 suggest...

Sensing and classification of rice (Oryza sativa L.) drought stress levels based on chlorophyll fluorescence

Q. XIA, L.J. FU, H. TANG, L. SONG, J.L. TAN, Y. GUO

Photosynthetica 2022, 60(1):102-109 | DOI: 10.32615/ps.2022.005  

Sensing and classification of drought stress levels are very important to agricultural production. In this work, rice drought stress levels were classified based on the commonly used chlorophyll a fluorescence (ChlF) parameter (F_v/F_m), feature data (induction features), and the whole OJIP induction (induction curve) by using a Support Vector Machine (SVM). The classification accuracies were compared with those obtained by the K-Nearest Neighbors (KNN) and the Ensemble model (Ensemble) correspondingly. The results show that the SVM can be used to classify drought stress levels of rice more accurately compared to the KNN...

Variability of the photosynthetic machinery tolerance when imposed to rapidly or slowly imposed dehydration in native Mediterranean plants

E. KOUTRA, C. CHONDROGIANNIS, G. GRAMMATIKOPOULOS

Photosynthetica 2022, 60(1):88-101 | DOI: 10.32615/ps.2022.003  

Dehydration affects the photosynthetic apparatus. The impact of dehydration on photosynthesis was assessed in twelve Mediterranean species representing different growth forms. Rapid and slow dehydration experiments were conducted to (1) compare the impact of water stress among species and growth forms, (2) rank species according to their drought tolerance. Rapid dehydration reduced the electron transport up to PSI, the reduction being linearly related to leaf relative water content (RWC), except for the deciduous species. Specific energy fluxes per reaction center and maximum photochemical activity of PSII remained relatively stable until...

An open Internet of Things (IoT)-based framework for feedback controlof photosynthetic activities

S. YUAN, H. TANG, L.J. FU, J.L. TAN, G. GOVINDJEE, Y. GUO

Photosynthetica 2022, 60(1):79-87 | DOI: 10.32615/ps.2021.066  

Active control of photosynthetic activities is important in plant physiological study. Although models of plant photosynthesis have been built at different scales, they have not been fully examined for their application in plant growth control. However, we do not have an infrastructure to support such experiments since current plant growth chambers usually use fixed control protocols. In our current paper, an open IoT-based framework is proposed. This framework allows a plant scientist or agricultural engineer, through an application programming interface (API), in a desirable programming language, (1) to gather environmental data and plant...

Exposed red leaves display adaptive adjustments in chlorophyll and photosystem ratios compatible with the shade imposed by anthocyanin accumulation

K. ZELIOU, A. KYZERIDOU, Y. PETROPOULOU

Photosynthetica 2022, 60(1):70-78 | DOI: 10.32615/ps.2021.062  

Foliar anthocyanins shape a peculiar shade in a red leaf's interior leading to uneven energy distribution between the two photosystems. Accordingly, a readjustment of PSII/PSI stoichiometry could restore excitation balance. To test this hypothesis, 77 K fluorescence emission spectra of thylakoids from green and red leaves of seven species with different pigment profiles were compared. The ratio of F₆₈₆/F₇₃₆ served as an indication of the PSII/PSI functional ratio. To avoid possible species-dependent differences in the measured parameters, plants showing intra-individual, intra-species, or intra-leaf variation in the expression...

Intersections: photosynthesis, abiotic stress, and the plant microbiome

B. DEMMIG-ADAMS, S.K. POLUTCHKO, M.C. ZENIR, P. FOUROUNJIAN, J.J. STEWART, M. LÓPEZ-POZO, W.W. ADAMS III

Photosynthetica 2022, 60(1):59-69 | DOI: 10.32615/ps.2021.065  

Climate change impacts environmental conditions that affect photosynthesis. This review examines the effect of combinations of elevated atmospheric CO₂, long photoperiods, and/or unfavorable nitrogen supply. Under moderate stress, perturbed plant source-sink ratio and redox state can be rebalanced but may result in reduced foliar protein content in C₃ plants and a higher carbon-to-nitrogen ratio of plant biomass. More severe environmental conditions can trigger pronounced photosynthetic downregulation and impair growth. We comprehensively evaluate available evidence that microbial partners may be able to support plant productivity...

Light quality, oxygenic photosynthesis and more

D. LAZAR, A. STIRBET, L.O. BJÖRN, G. GOVINDJEE

Photosynthetica 2022, 60(1):25-58 | DOI: 10.32615/ps.2021.055  

Oxygenic photosynthesis takes place in thylakoid membranes (TM) of cyanobacteria, algae, and higher plants. It begins with light absorption by pigments in large (modular) assemblies of pigment-binding proteins, which then transfer excitation energy to the photosynthetic reaction centers of photosystem (PS) I and PSII. In green algae and plants, these light-harvesting protein complexes contain chlorophylls (Chls) and carotenoids (Cars). However, cyanobacteria, red algae, and glaucophytes contain, in addition, phycobiliproteins in phycobilisomes that are attached to the stromal surface of TM, and transfer excitation energy to the reaction centers via...

George C. Papageorgiou and the protective role of glycine betaine in activation and stabilization of the oxygen-evolving photosystem II complex

N. MURATA, K. STAMATAKIS

Photosynthetica 2022, 60(1):21-24 | DOI: 10.32615/ps.2021.056  

We present here our adventures in research in photosynthesis with George C. Papageorgiou (1933-2020) focusing on George's initiative in the discovery of the protective effects of glycine betaine on the oxygen-evolving photosystem II complex. We end with a brief description of research on glycine betaine-synthesizing transgenic cyanobacteria. Two of us, Norio Murata (in Japan) and Kostas Stamatakis (in Greece), and all our collaborators, have the highest respect for George, and we miss him and our intense discussions with him on various topics of photosynthesis research.

Differences in susceptibility to photoinhibition do not determinegrowth rate under moderate light in batch or turbidostat - a studywith five green algae

H. MATTILA, D. VALEV, K.B. MISHRA, V. HAVURINNE, O. VIRTANEN, M. ANTINLUOMA, E. TYYSTJÄRVI

Photosynthetica 2022, 60(1):10-20 | DOI: 10.32615/ps.2021.054  

To understand growth limitations of photosynthetic microorganisms, and to investigate whether batch growth or certain photosynthesis-related parameters predict a turbidostat (continuous growth at constant biomass concentration) growth rate, five green algal species were grown in a photobioreactor in batch and turbidostat conditions and their susceptibilities to photoinhibition of photosystem II as well as several photosynthetic parameters were measured. Growth rates during batch and turbidostat modes varied independently of each other; thus, a growth rate measured in a batch cannot be used to determine the continuous growth rate. Greatly different...

Contents of photosynthetic pigments and ratios of chlorophyll a/b and chlorophylls to carotenoids (a+b)/(x+c) in C₄ plants as compared to C₃ plants

H.K. LICHTENTHALER, F. BABANI

Photosynthetica 2022, 60(1):3-9 | DOI: 10.32615/ps.2021.041  

The content of chlorophylls (Chl) (a+b), total carotenoids (x+c), and the pigment ratios of Chl a/b and Chls to carotenoids (a+b)/(x+c) of green leaves of five C₄ plants were determined and compared to those of C₃ plants. The C₄ plants were: Pacific and Chinese silvergrass (Miscanthus floridulus and Miscanthus sinensis), sugar cane (Saccharum officinarum) as well as feed and sugar maize (Zea mays). The three C₃ plants were beech, ginkgo, and oak. C₄ plants possess higher values for the ratio Chl a/b...

EDITORIAL

O. PRÁŠIL, RADEK KAŇA, G. GOVINDJEE

Photosynthetica 2022, 60(1):1-2 | DOI: 10.32615/ps.2022.017  

Evaluation of the photosynthetic characteristics of upland cotton (Gossypium hirsutum L.) germplasm based on chlorophyll a fluorescence

Y. SUN, X.M. XU, Y.H. JIA, W.Q. DONG, X.M. DU, H.Q. DENG, C.M. TANG

Photosynthetica 2021, 59(4):693-701 | DOI: 10.32615/ps.2021.043  

Handy Plant Efficiency Analyser (Handy PEA) provides a method for the high-throughput screening of photosynthetic germplasm. However, the large number of chlorophyll a fluorescence parameters (CFPs) from PEA and the inconsistency of CFP applications among studies greatly limit the accuracy of photosynthesis analyses. In this study, all 53 CFPs of 186 upland cotton cultivars (strains) were measured at 12:00 and 17:00 h. Thirty-two CFPs were selected according to biological importance, and the CFP relationships were determined. Differences in the response ability of cotton cultivars (strains) to high light intensity stress were demonstrated...

The melatonin receptor CAND2 is involved in the regulation of photosynthesis and chloroplast gene expression in Arabidopsis thaliana under photooxidative stress

I.A. BYCHKOV, N.V. KUDRYAKOVA, E.S. POJIDAEVA, V.V. KUSNETSOV

Photosynthetica 2021, 59(4):683-692 | DOI: 10.32615/ps.2021.061  

Melatonin is a well-known bioactive molecule able to mitigate photooxidative damage caused by excess light. Here we have shown that mutant Arabidopsis lines with disrupted genes for melatonin putative receptor CAND2/PMTR1 and GPA1 encoding the α-subunit of heterotrimeric G-protein were partially insensitive to melatonin treatment under high light stress. They exhibited a higher degree of photodamage due to a significantly decreased photosynthetic activity and diminished expression of chloroplast and nuclear-encoded genes and the corresponding proteins. A possible mechanism for melatonin-dependent regulation of chloroplast...

Crop responses and management strategies under shade and drought stress

I. SHAFIQ, S. HUSSAIN, B. HASSAN, A. RAZA, I. AHMAD, M.A. ASGHAR, Z. WANG, T. TAN, S. LI, X. TAN, A. GHAFOOR, A. MANAF, M. ANSAR, F. YANG, W. YANG

Photosynthetica 2021, 59(4):664-682 | DOI: 10.32615/ps.2021.057  

The occurrence of shade and drought stress either individually or simultaneously causes altered morphophysiological and molecular responses in crops. Nevertheless, responses of crop plants to combined shade and drought stress are unique as compared to those of individually occurring stress which urges need to study and identify distinctions, commonalities, and the interaction between responses of plants to these concurrent stress factors. In the present review, we outlined currently available knowledge on responses of plants to shade and drought stress on a shared as well as the unique basis and tried to find a common thread potentially underlying...

Zinc and cadmium as modulating factors of the morphophysiological responses of Alternanthera tenella Colla (Amaranthaceae) under in vitro conditions

E. CLAIRVIL, J.P.R. MARTINS, P.C.S. BRAGA, S.W. MOREIRA, L.T. CONDE, R. CIPRIANO, A.R. FALQUETO, A.B.P.L. GONTIJO

Photosynthetica 2021, 59(4):652-663 | DOI: 10.32615/ps.2021.059  

Zinc (Zn) plays an important role in the physiological processes in plants and may mitigate trace element stress. The aim was to evaluate the morphophysiological responses of Alternanthera tenella plants exposed to cadmium (Cd) and Zn under in vitro conditions. Segments of A. tenella were transferred to flasks containing medium supplemented with different combinations of Cd (0, 75, or 150 μM) and Zn (0, 750, or 1,500 μM) concentrations, totalizing nine treatments. We assessed the growth traits, anatomy, chlorophyll a fluorescence by OJIPs, and tolerance index (TI). With exposure only to Cd, the plants showed physiological...

Response of physiological characteristics and grain yield of winter wheat varieties to long-term heat stress at anthesis

C.H. GAO, M. SUN, S. ANWAR, B. FENG, A.X. REN, W. LIN, Z.Q. GAO

Photosynthetica 2021, 59(4):640-651 | DOI: 10.32615/ps.2021.060  

Heat stress has become more common in recent years, limiting wheat production in Huang-Huai-Hai plain in China. To identify the effect of long-term heat stress on wheat production, two heat-resistant (JM44, JM23) and two heat-sensitive (XM26, GC8901) wheat varieties were sown in heat tents and normal conditions, and heat stress (9 to 12℃ higher than control) was imposed for seven days at post-anthesis. All varieties under heat stress exhibited early senescence and reduced grain-filling rate, while the grain-filling period of heat-tolerant varieties was longer than that of the heat-sensitive. Furthermore, long-term heat stress significantly reduced...

Fatty acid composition and cpDNA content in Arabidopsis thaliana mutants deprived of EGY1 protease

M. ADAMIEC, M. SZOMEK, E. GABAŁA, J. DOBROGOJSKI, L. MISZTAL, R. LUCIŃSKI

Photosynthetica 2021, 59(4):633-639 | DOI: 10.32615/ps.2021.053  

EGY1 (ethylene-dependent gravitropism-deficient and yellow-green 1) is an intramembrane metalloprotease located in chloroplasts, involved in many diverse processes including chloroplast development, chlorophyll biosynthesis, and the ethylene-dependent gravitropic response. Plants deprived of this protease display pleiotropic effects such as the yellow-green early senescence phenotype and a poorly developed thylakoid system membrane in the mature chloroplasts. We applied the GC/MS technique to analyze the changes in fatty acid composition in two egy1 mutant lines. We used DAPI staining and transmission electron microscopy methods to establish...

Effects of red to far-red light ratio on growth and photosynthetic characteristics of tomato seedlings under calcium nitrate stress

X.T. ZHOU, Z.L. LI, J.J. HE, X.Y. WANG, Q.L. LIU, J. HUANG, Y.D. XIE, Z.Q. HE

Photosynthetica 2021, 59(4):625-632 | DOI: 10.32615/ps.2021.052  

Secondary soil salinization causes plant stress, which can be relieved by different ratios of red to far-red light (R:FR). Our study aimed to elucidate the role of low R:FR ratios treatments on photosynthesis and growth of tomato seedlings in salinized soils. Tomato seedlings were treated under three R:FR ratios and calcium nitrate was applied simultaneously. The results showed that the treatments under low R:FR ratios stimulated growth parameters of tomato seedlings under calcium nitrate stress, the best impact being achieved at the R:FR ratio of 0.7 in this experiment. Low R:FR ratios treatments increased proline content as well as PSII maximum efficiency,...

Mitochondrial alternative oxidase pathway acts as an electron sink during photosynthetic induction in Rumex K-1 leaves

D.D. CHENG, L.T. ZHANG

Photosynthetica 2021, 59(4):615-624 | DOI: 10.32615/ps.2021.047  

Chloroplast PSII photochemical efficiency is upregulated more rapidly than CO₂ assimilation during photosynthesis induction, suggesting the existence of other electron sinks than that of CO₂ assimilation. We hypothesized that the mitochondrial alternative oxidase (AOX) pathway could be such a sink. Inhibition of the AOX restricted light activation of the malate-oxaloacetate shuttle and caused an excessive reduction of PSI acceptor side and substantial accumulation of Q_A^-, hindering the photosynthetic linear electron transport rate (ETR) and leading to an imbalance between light energy absorption and exploitation...

James Barber (1940-2020): A very remarkable biochemist of our time

G. GOVINDJEE

Photosynthetica 2021, 59(4):606-614 | DOI: 10.32615/ps.2021.058  

Photoprotective roles of ascorbate and PSII cyclic electron flow in the response of the seagrass Zostera marina to oxygen-evolving complex photoinactivation

W. ZHAO, Q.S. ZHANG, Y. TAN, Z. LIU, M.Y. MA, M.X. WANG, C.Y. LUO

Photosynthetica 2021, 59(4):600-605 | DOI: 10.32615/ps.2021.051  

The oxygen-evolving complex (OEC) of Zostera marina is prone to deactivation under visible light, which results in a formation of the long-lived radical P₆₈₀⁺. The mechanism to prevent damage caused by P₆₈₀⁺ remains unclear. In this study, following light exposure, the upregulation in ascorbate (AsA) content and the presence of PSII cyclic electron flow (PSII-CEF) provide evidence that AsA and PSII-CEF donate electrons to PSII. Furthermore, a factorial design experiment with different combinations of inhibition of AsA and PSII-CEF demonstrates that both inhibition treatments lead to decreases in maximal...

The moderating role of population succession in the adaptive responses of Synechococcus assemblages: evidence from light intensity simulation experiment

T. WANG, X. CHEN, J.L. LI, S. QIN, Y.L. CUI, F. XU

Photosynthetica 2021, 59(4):587-599 | DOI: 10.32615/ps.2021.050  

Synechococcus is one of the most abundant photoautotrophic picoplankton in the marine ecosystem. However, it is not clear how Synechococcus assemblages respond to light intensity variation in a genus group. Here, enriched Synechococcus assemblages from in situ coastal seawater were subjected to light intensity simulation experiments in a range of 9-243 μmol(photon) m^-2 s^-1. Characteristics concerning physiology, genomics, and metatranscriptomics were analyzed. Physiologically, the fitting model predicted photosynthesis indications and pigment contents increased with different trends following the light...

Insights into nanoparticle-induced changes in plant photosynthesis

M. GHORBANPOUR, A. MOVAHEDI, M. HATAMI, K. KARIMAN, F. BOVAND, M.A. SHAHID

Photosynthetica 2021, 59(4):570-586 | DOI: 10.32615/ps.2021.049  

Photosynthesis can be affected by nanoparticles (NPs) both negatively (e.g., through decreasing the chlorophyll content and electron transport rate, damages to chloroplast components, etc.) or positively (e.g., via enhancing chlorophyll content, the activity of Rubisco enzyme, the performance of PSII, and CO₂ harvesting, as well as broadening the chloroplast photoabsorption spectrum). Enhanced photosynthetic efficiency could be a possible impact of NPs on photosynthetic organisms of major economic and ecological significance (e.g., crops and algae), which warrants an in-depth understanding of NPs interactions...

Photosynthetic traits and biochemical responses in strawberry (Fragaria × ananassa Duch.) leaves supplemented with LED lights

G. LAURIA, E. LO PICCOLO, E. PELLEGRINI, E. BELLINI, T. GIORDANI, L. GUIDI, G. LORENZINI, F. MALORGIO, R. MASSAI, C. NALI, L. PAOLI, D. REMORINI, L. SANITA' DI TOPPI, P. VERNIERI, M. LANDI

Photosynthetica 2021, 59(4):557-569 | DOI: 10.32615/ps.2021.048  

Selected light wavebands promote plant development and/or the biosynthesis of targeted metabolites. This work offers new insights on the effects of red (R), green (G), blue (B), and white (W - R:G:B; 1:1:1) LED light supplementation on physiochemical traits of strawberry leaves. Gas exchange and chlorophyll fluorescence parameters, photosynthetic pigments, and superoxide anion (^*O₂^-) content were analysed in plants grown for 1 (T1) and 17 (T17) d with light supplementations. At T1, light supplementations resulted in the enhancement of the de-epoxidation state of xanthophylls and nonphotochemical quenching, but no changes...

Blue light dosage affects photosynthesis, chlorophyll, and antioxidant properties of Mesembryanthemum crystallinum

H. ZHANG, Y. TU, J. KANG, W. SONG, L. ZHENG

Photosynthetica 2021, 59(4):547-556 | DOI: 10.32615/ps.2021.046  

Mesembryanthemum crystallinum is an annual succulent plant that is being used as an emerging healthy leafy vegetable. To investigate the growth and physiological response of M. crystallinum to artificial lighting, five different light treatments were applied at 150 µmol(photon) m^-2 s^-1, which were white (W), different rations of red/blue (B) (15, 40, and 70%B), and blue (100%B), respectively. Our results showed that plants could gain as much as edible leaf area and dry mass with a certain ratio of blue (40%) in comparison with W. Plants grown under 100%B resulted in reduced photosynthetic rate, leaf area, and fresh...

Effects of temperature and nitrogen application on photosynthetic characteristics and the absorption and distribution of carbon and nitrogen in apple plants

H.H. ZHANG, H.F. LIU, Z. LI, H.F. DING, Z.X. XUE, F.Y. ZHAO, S.L. YU, K. YU

Photosynthetica 2021, 59(4):538-546 | DOI: 10.32615/ps.2021.044  

Low temperature has negative effects on apple photosynthesis by inhibiting the accumulations of photosynthates and nitrogen. The interactive effects of low temperature and nitrogen application on photosynthetic parameters and the absorption and distribution of carbon and nitrogen in different organs were assessed to investigate if nitrogen application can relieve the low-temperature stress on gas exchange and the accumulations of carbon and nitrogen inside the apple plants. No matter under normal or low-temperature conditions, nitrogen application both improved the photosynthetic parameters including net photosynthetic rate, intercellular CO₂...

Photosynthetic apparatus performance and anatomical modulations of Alcantarea imperialis (Bromeliaceae) exposed to selenium during in vitro growth

J.P.R. MARTINS, S.W. MOREIRA, P.C.S. BRAGA, L.T. CONDE, R. CIPRIANO, A.R. FALQUETO, A.B.P.L. GONTIJO

Photosynthetica 2021, 59(4):529-537 | DOI: 10.32615/ps.2021.042  

Elements not usually included in culture medium formulations, such as selenium (Se), may have beneficial effects on micropropagated plants. We evaluated the effects of Se on the physiological and anatomical responses of Alcantarea imperialis during in vitro culture. Plants were cultured in a medium containing a gradient of Se concentrations (0, 4, 8, 16, or 32 µM Se). After 56 d, the growth traits, chlorophyll a fluorescence, and root and leaf anatomy were analyzed. The fresh mass declined at the highest Se concentration. Higher Se concentrations induced bigger stomata, while the stomatal density decreased. Plants cultured...