Changes in the epidermal configuration reveal marked alteration in number of stomata, epidermal cells and stomatal indices in leaf samples collected from polluted zones

Structural Changes in Stomata in Plants Exposed to Air Pollution

by Shri P. U., Haritha (2019)

P. Usha Shri 1
and Haritha 2

1. Lecturer, Department of Botany, St. Ann’s College for women Mehdipatnam, Hyderabad-28, Telangana state
2. Student, St. Ann’s College for women Mehdipatnam, Hyderabad-28, Telangana state

===

In IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) – e-ISSN: 2319-2402,p – ISSN: 2319-2399 – Vol. 13(8): 66-70 – DOI: 10.9790/2402-1308016670 –

http://iosrjournals.org/iosr-jestft/papers/Vol13-%20Issue%208/Series-1/J1308016670.pdf

Abstract

Air pollution, is now almost inescapable component of urban life effecting both plants and animals equally. The changes in the epidermal configuration reveal marked alteration in number of stomata, epidermal cells and stomatal indices in leaf samples collected from polluted zones that can be used as biomarkers of air
pollution.

These pollutants not only affect the morphology of plants but also alter the physiology. Reduction in various parameters of the two plant species studied from polluted sites clearly indicate the deleterious effect of air pollution on plant health.

It is evident from the present study that the air pollutants such as SPM, SOx, NOx
and O3 from automobile exhaust and industries along with many other unknown pollutants are responsible for bad air quality and are responsible for altering the epidermal structures in both Tridax and Datura plants growing in polluted zones.

Response of Plant Photosynthesis and Stomatal Conductance to Fine Particulate Matter (PM2.5)

The Response of Plant Photosynthesis and Stomatal Conductance to Fine Particulate Matter (PM_2.5) based on Leaf Factors Analyzing

by Li Y., Wang Y., Wang B., Wang Y., Yu W. (2019)

Yifan Li, Yujie Wang, Bin Wang, Yunqi Wang, Weiqing Yu,

1. School of Soil and Water Conservation at Beijing Forestry University, Beijing, China

2. Chongqing Jinyun Forest Ecological Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing, China

===

In J. Plant Biol. 62: 120-128 – https://doi.org/10.1007/s12374-018-0254-9 –

https://link.springer.com/article/10.1007/s12374-018-0254-9#citeas

Abstract

The effects of particles on the photosynthesis of vegetation, which is a sink for fine particulate matter (PM_2.5) deposition, are still not well understood. Here, we carried out indoor measurements to evaluate the variation dynamics of net photosynthetic rate and stomatal conductance of four plant species with different leaf characteristics under different PM_2.5 levels. Then tree leaves were sampled and the groove proportion, leaf trichome density, stomatal density and stomatal size were quantitatively studied by scanning electron microscopy (SEM). The stomatal conductance of the 4 species had a close positive correlation with photosynthetic rate. Net photosynthetic rate and stomatal conductance declined over time at elevated PM_2.5, and the rate of the decline became more rapid with higher concentration of PM_2.5. The inhibiting effect might be caused by the closure of the stomata and the decrease of stomatal conductance, which was proved by the reduction of the stomatal size of under the condition of PM_2.5 pollution. Leaf trichome and groove seemed to show a protective role for plants from PM_2.5 exposure and be responsible for the difference of photosynthetic rate and stomatal conductance under the condition of PM_2.5 pollution. The higher groove proportion and the presence of trichomes on the leaf surface in Neolitsea aurata and Lindera kwangtungensis absorbed some particulate matters and buffered the effect of PM_2.5 pollution on stomata.

Identification of SCORD5 begins to implicate an important role of stress-associated protein translation in stomatal guard cell signaling in response to microbe-associated molecular patterns and bacterial infection

Morphological phenotypes of scord mutants of 4 to 5 weeks old.(A) Rosettes. (B) Stomata densities of leaf abaxial surfaces. (C) Scanning electron microscopy pictures of leaf abaxial surfaces of Col-7 and scord6 plants. Note that raised central ridges in stomata are missing in the scord6 mutant.

A genetic screen reveals Arabidopsis stomatal and/or apoplastic defenses against Pseudomonas syringae pv. tomato DC3000

by Zeng W., Brutus A., Kremer J. M., Withers J. C., Gao X., Jones A. D., He S. Y. (2011)

Department of Energy (DOE)-Plant Research Laboratory, Michigan State University, East Lansing, Michigan, United States of America.

In PLoS Pathog. 2011 Oct.7(10):e1002291 – doi: 10.1371/journal.ppat.1002291 – Epub 2011 Oct 6 –

https://www.ncbi.nlm.nih.gov/pubmed/21998587

Abstract

Bacterial infection of plants often begins with colonization of the plant surface, followed by entry into the plant through wounds and natural openings (such as stomata), multiplication in the intercellular space (apoplast) of the infected tissues, and dissemination of bacteria to other plants. Historically, most studies assess bacterial infection based on final outcomes of disease and/or pathogen growth using whole infected tissues; few studies have genetically distinguished the contribution of different host cell types in response to an infection. The phytotoxin coronatine (COR) is produced by several pathovars of Pseudomonas syringae. COR-deficient mutants of P. s. tomato (Pst) DC3000 are severely compromised in virulence, especially when inoculated onto the plant surface. We report here a genetic screen to identify Arabidopsis mutants that could rescue the virulence of COR-deficient mutant bacteria. Among the susceptible to coronatine-deficient Pst DC3000 (scord) mutants were two that were defective in stomatal closure response, two that were defective in apoplast defense, and four that were defective in both stomatal and apoplast defense. Isolation of these three classes of mutants suggests that stomatal and apoplastic defenses are integrated in plants, but are genetically separable, and that COR is important for Pst DC3000 to overcome both stomatal guard cell- and apoplastic mesophyll cell-based defenses. Of the six mutants defective in bacterium-triggered stomatal closure, three are defective in salicylic acid (SA)-induced stomatal closure, but exhibit normal stomatal closure in response to abscisic acid (ABA), and scord7 is compromised in both SA- and ABA-induced stomatal closure. We have cloned SCORD3, which is required for salicylic acid (SA) biosynthesis, and SCORD5, which encodes an ATP-binding cassette (ABC) protein, AtGCN20/AtABCF3, predicted to be involved in stress-associated protein translation control. Identification of SCORD5 begins to implicate an important role of stress-associated protein translation in stomatal guard cell signaling in response to microbe-associated molecular patterns and bacterial infection.

Drought resistance is regulated by stomatal characteristics through a decrease in transpiration rate in order to improve integral WUE and photosynthetic performance, and through sustaining a higher ear photosynthetic rate, therefore enhancing overall drought-resistance

Improving water-use efficiency by decreasing stomatal conductance and transpiration rate to maintain higher ear photosynthetic rate in drought-resistant wheat

by Li Y., Li H., Li Y., Zhang S. (2017)

Yuping Li^a1, Hongbin Li^b1, Yuanyuan Li^a, Suiqi Zhang^ab

^a State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China

^b State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China

===

In The Crop Journal5: 231–239 – https://doi.org/10.1016/j.cj.2017.01.001 –

https://www.sciencedirect.com/science/article/pii/S2214514117300016?via%3Dihub

Abstract

In wheat, the ear is one of the main photosynthetic contributors to grain filling under drought stress conditions. In order to determine the relationship between stomatal characteristics and plant drought resistance, photosynthetic and stomatal characteristics and water use efficiency (WUE) were studied in two wheat cultivars: the drought-resistant cultivar ‘Changhan 58’ and the drought-sensitive cultivar ‘Xinong 9871’. Plants of both cultivars were grown in pot conditions under well-watered (WW) and water-stressed (WS) conditions. In both water regimes, ‘Changhan 58’ showed a significantly higher ear photosynthetic rate with a lower rate of variation and a significantly higher percentage variation of transpiration compared to control plants at the heading stage under WS conditions than did ‘Xinong 9871’ plants. Moreover, ‘Changhan 58’ showed lower stomatal density (SD) and higher stomatal area per unit organ area (A) under both water conditions. Water stress decreased SD, A, and stomatal width (SW), and increased stomatal length in flag leaves (upper and lower surfaces) and ear organs (awn, glume, lemma, and palea), with the changes more pronounced in ear organs than in flag leaves. Instantaneous WUE increased slightly, while integral WUE improved significantly in both cultivars. Integral WUE was higher in ‘Changhan 58’, and increased by a greater amount, than in ‘Xinong 9871’. These results suggest that drought resistance in ‘Changhan 58’ is regulated by stomatal characteristics through a decrease in transpiration rate in order to improve integral WUE and photosynthetic performance, and through sustaining a higher ear photosynthetic rate, therefore enhancing overall drought-resistance.

Whole-plant transpiration per unit of green leaf area (TGLA) was monitored continuously and stomatal conductance and maximum photosynthetic capacity were measured during sunny conditions

Genotypic variation in whole-plant transpiration efficiency in sorghum only partly aligns with variation in stomatal conductance

by Geetika G., van Oosterom E. J., George-Jaeggli B., Mortlock M. Y., Deifel K. S., McLean G., Hammer G. L. (2018)

Geetika Geetika ^AE , Erik J. van Oosterom ^A , Barbara George-Jaeggli ^BC , Miranda Y. Mortlock ^A , Kurt S. Deifel ^A , Greg McLean ^D and Graeme L. Hammer ^A–

^A The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, St Lucia, Qld 4072, Australia.

^B The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Hermitage Research Facility, Warwick, Qld 4370, Australia.

^C Agri-Science Queensland, Department of Agriculture and Fisheries, Warwick, Qld 4370, Australia.

^D Agri-Science Queensland, Department of Agriculture and Fisheries, Toowoomba, Qld 4350, Australia.

===

In Functional Plant Biology – https://doi.org/10.1071/FP18177 –

https://www.publish.csiro.au/FP/FP18177

Abstract

Water scarcity can limit sorghum (Sorghum bicolor (L.) Moench) production in dryland agriculture, but increased whole-plant transpiration efficiency (TE_wp, biomass production per unit of water transpired) can enhance grain yield in such conditions. The objectives of this study were to quantify variation in TE_wp for 27 sorghum genotypes and explore the linkages of this variation to responses of the underpinning leaf-level processes to environmental conditions. Individual plants were grown in large lysimeters in two well-watered experiments. Whole-plant transpiration per unit of green leaf area (TGLA) was monitored continuously and stomatal conductance and maximum photosynthetic capacity were measured during sunny conditions on recently expanded leaves. Leaf chlorophyll measurements of the upper five leaves of the main shoot were conducted during early grain filling. TE_wp was determined at harvest. The results showed that diurnal patterns in TGLA were determined by vapour pressure deficit (VPD) and by the response of whole-plant conductance to radiation and VPD. Significant genotypic variation in the response of TGLA to VPD occurred and was related to genotypic differences in stomatal conductance. However, variation in TGLA explained only part of the variation in TE_wp, with some of the residual variation explained by leaf chlorophyll readings, which were a reflection of photosynthetic capacity. Genotypes with different genetic background often differed in TE_wp, TGLA and leaf chlorophyll, indicating potential differences in photosynthetic capacity among these groups. Observed differences in TE_wp and its component traits can affect adaptation to drought stress.

The tendency of stomata to remain open despite water stress and loss of bulk leaf Ψp is related to the presence of an emerged panicle

The Effect of Flowering on Stomatal Response to Water Stress in Pearl Millet (Pennisetum americanum [L.] Leeke)

by Henson I. E., Mahalakshmi V., Alagarswamy G., Bidinger F. R. (1984)

In Journal of Experimental Botany 35(151): 219-226 –

https://www.jstor.org/stable/23690887?seq=1

Abstract

Stomata on upper leaves of drought-stressed pearl millet (Pennisetum americanum [L.] Leeke) crops were more open in flowering (F) than in pre-flowering (PF) plants. This was not due to differences in leaf water potential (Ψ). Stomata of PF plants closed when Ψ fell to about —1.7 MPa, while on F plants stomata closed only when Ψ approached —2.3 MPa. Osmotic adjustment did not account for these differences as relations between turgor potential (Ψp) and Ψ were similar in F and PF plants. While stomata of PF plants closed as Ψp became zero, in F plants stomata remained open even after bulk leaf turgor was lost. Differences between F and PF plants were not explained by differences in age of leaves sampled. However, leaves of water-stressed PF plants had higher levels of abscisic acid (ABA) than leaves of F plants, despite similarities in water status. From these results and from relationships between gL and stage of panicle development, it is concluded that the tendency of stomata to remain open despite water stress and loss of bulk leaf Ψp is related to the presence of an emerged panicle. Hypotheses which account for this effect are discussed.

Direct epidermal evaporation controls stomatal guard cell behaviour in responses of stomata to VPD

Effect of boundary layer conductance on the response of stomata to humidity

by Bunce J. A. (1985)

===

In Plant, Cell and Environment 8: 55–57 –  https://doi.org/10.1111/j.1365-3040.1985.tb01209.x –

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3040.1985.tb01209.x

Abstract

Leaf conductance responses to leaf to air water vapour partial pressure difference (VPD) have been measured at air speeds of 0.5 and 3.0 ms⁻¹ in single attached leaves of three species in order to test the hypothesis that leaf conductance response to VPD is controlled by evaporation from the outer surface of the epidermis, rather than by evaporation through stomata. Total conductance decreased linearly with increassing VPD at both air speeds, but was decreased 1.6 3.0 times as much as by a given incrase in VPD at high than at low air speed. depending on species. In all species the relationship between leaf conductance and the gradient for evaporation from the epidermis was the same at both values of boundary layer conductance, supporting the hypothesis that direct epidermal evaporation controls stomatal guard cell behaviour in responses of stomata to VPD in these species.