Moisture stress

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Moisture stress is a form of abiotic stress that occurs when the moisture of plant tissues is reduced to suboptimal levels. Water stress occurs in response to atmospheric and soil water availability when the transpiration rate exceeds the rate of water uptake by the roots and cells lose turgor pressure. Moisture stress is described by two main metrics, water potential and water content. [1] [2] [3]

Moisture stress has an effect on stomatal opening, mainly causing a closure in stomata as to reduce the amount of carbon dioxide assimilation. [4] Closing of the stomata also slows the rate of transpiration, which limits water loss and helps to prevent the wilting effects of moisture stress. [5] This closing can be triggered by the roots sensing dry soil and in response producing the hormone ABA which when transported up the xylem into the leaves will reduce stomatal conductance and wall extensibility of growing cells. This lowers the rates of transpiration, photosynthesis and leaf expansion. ABA also increases the loosening of growing root cell walls and in turn increases root growth in an effort to find water in the soil. [6]

Phenotypic response of plants to long-term water stress was measured in corn and showed that plants respond to water stress with both an increase in root growth both laterally and vertically. [7] In all Droughted conditions the corn showed decrease in plant height and yield due to the decrease in water availability. [8]

Genes induced during water-stress conditions are thought to function not only in protecting cells from water deficit by the production of important metabolic proteins but also in the regulation of genes for signal transduction in the water-stress response. There are four pathways that have been described that show the plants genetic response to moisture stress; two are ABA dependent while two are ABA independent. They all affect gene expression that increases the plants water stress tolerance. [9]

The effects of moisture stress on photosynthesis can depend as much on the velocity and degree of photosynthetic recovery, as it depends on the degree and velocity of photosynthesis decline during water depletion. Plants that are subjected to mild stress can recover in 1–2 days however, plants subjected to severe water stress will only recover 40-60% of its maximum photosynthetic rates the day after re watering and may never reach maximum photosynthetic rates. The recovery from moisture stress starts with an increase in water content in leaves reopening the stomata then the synthesis of photosynthetic proteins. [10] [11]

See also

Related Research Articles

Abiotic stress is the negative impact of non-living factors on the living organisms in a specific environment. The non-living variable must influence the environment beyond its normal range of variation to adversely affect the population performance or individual physiology of the organism in a significant way.

<span class="mw-page-title-main">Vascular plant</span> Clade of plants with xylem and phloem

Vascular plants, also called tracheophytes or collectively tracheophyta, are plants that have lignified tissues for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue to conduct products of photosynthesis. The group includes most land plants other than mosses.

<span class="mw-page-title-main">Stoma</span> In plants, a variable pore between paired guard cells

In botany, a stoma, also called a stomate, is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spaces of the leaf and the atmosphere. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that regulate the size of the stomatal opening.

<span class="mw-page-title-main">Photorespiration</span> Process in plant metabolism

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<span class="mw-page-title-main">Abscisic acid</span> Plant hormone

Abscisic acid is a plant hormone. ABA functions in many plant developmental processes, including seed and bud dormancy, the control of organ size and stomatal closure. It is especially important for plants in the response to environmental stresses, including drought, soil salinity, cold tolerance, freezing tolerance, heat stress and heavy metal ion tolerance.

Mesophytes are terrestrial plants which are adapted to neither particularly dry nor particularly wet environments. An example of a mesophytic habitat would be a rural temperate meadow, which might contain goldenrod, clover, oxeye daisy, and Rosa multiflora. Mesophytes prefer soil and air of moderate humidity and avoid soil with standing water or containing a great abundance of salts. They make up the largest ecological group of terrestrial plants, and usually grow under moderate to hot and humid climatic regions.

<span class="mw-page-title-main">Ecohydrology</span>

Ecohydrology is an interdisciplinary scientific field studying the interactions between water and ecological systems. It is considered a sub discipline of hydrology, with an ecological focus. These interactions may take place within water bodies, such as rivers and lakes, or on land, in forests, deserts, and other terrestrial ecosystems. Areas of research in ecohydrology include transpiration and plant water use, adaption of organisms to their water environment, influence of vegetation and benthic plants on stream flow and function, and feedbacks between ecological processes, the soil carbon sponge and the hydrological cycle.

<span class="mw-page-title-main">Guard cell</span> Paired cells that control the stomatal aperture

Guard cells are specialized plant cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore. The stomatal pores are largest when water is freely available and the guard cells become turgid, and closed when water availability is critically low and the guard cells become flaccid. Photosynthesis depends on the diffusion of carbon dioxide (CO2) from the air through the stomata into the mesophyll tissues. Oxygen (O2), produced as a byproduct of photosynthesis, exits the plant via the stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Plants must balance the amount of CO2 absorbed from the air with the water loss through the stomatal pores, and this is achieved by both active and passive control of guard cell turgor pressure and stomatal pore size.

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<span class="mw-page-title-main">Transpiration</span> Process of water moving through a plant parts

Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients. When water uptake by the roots is less than the water lost to the atmosphere by evaporation, plants close small pores called stomata to decrease water loss, which slows down nutrient uptake and decreases CO2 absorption from the atmosphere limiting metabolic processes, photosynthesis, and growth.

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Water-use efficiency (WUE) refers to the ratio of plant biomass to water lost by transpiration, can be defined either at the leaf, at the whole plant or a population/stand/field level:

Stomatal conductance, usually measured in mmol m−2 s−1 by a porometer, estimates the rate of gas exchange and transpiration through the leaf stomata as determined by the degree of stomatal aperture.

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<span class="mw-page-title-main">9-cis-epoxycarotenoid dioxygenase</span> Class of enzymes

9-cis-epoxycarotenoid dioxygenase (EC 1.13.11.51, nine-cis-epoxycarotenoid dioxygenase, NCED, AtNCED3, PvNCED1, VP14) is an enzyme in the biosynthesis of abscisic acid (ABA), with systematic name 9-cis-epoxycarotenoid 11,12-dioxygenase. This enzyme catalyses the following chemical reaction

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References

  1. ↑ Waring, R. H.; Cleary, B. D. (1967). "Plant Moisture Stress: Evaluation by Pressure Bomb". Science. 155 (3767): 1248–54. Bibcode:1967Sci...155.1248W. doi:10.1126/science.155.3767.1248. PMID   17847540. S2CID   2516520.
  2. ↑ Chappelka, Arthur H.; Freer-Smith, Peter H. (1995). "Predisposition of trees by air pollutants to low temperatures and moisture stress". Environmental Pollution. 87 (1): 105–117. doi:10.1016/S0269-7491(99)80013-X. PMID   15091613.
  3. ↑ Lee, J. A.; Stewart, G. R. (1 January 1971). "Desiccation Injury in Mosses. I. Intra-Specific Differences in the Effect of Moisture Stress on Photosynthesis". The New Phytologist. 70 (6): 1061–1068. doi:10.1111/j.1469-8137.1971.tb04588.x. JSTOR   2431023.
  4. ↑ Hand, JM; Young, E; Vasconcelos, AC (1982). "Leaf water potential, stomatal resistance, and photosynthetic response to water stress in peach seedlings". Plant Physiol. 69 (5): 1051–4. doi:10.1104/pp.69.5.1051. PMC   426357 . PMID   16662343.
  5. ↑ Freeman, Scott (2014). Biological Science: Fifth Edition. USA: Pearson Education, Inc. p. 765. ISBN   978-0-321-74367-1.
  6. ↑ Lambers, Hans; Chapin II, F. Stuart; Pons, Thijs L. (2008). Plant physiological Ecology. New York, NY: Springer. p. 349. ISBN   978-0-387-78340-6.
  7. ↑ Singh, Chandrakant; Wang-Erlandsson, Lan; Fetzer, Ingo; Rockström, Johan; van der Ent, Ruud (2020-12-05). "Rootzone storage capacity reveals drought coping strategies along rainforest-savanna transitions". Environmental Research Letters. 15 (12): 124021. Bibcode:2020ERL....15l4021S. doi: 10.1088/1748-9326/abc377 . ISSN   1748-9326.
  8. ↑ Weaver, J.E. (1926) Root Development of Field Crops. McGraw Hill, New York.
  9. ↑ Shinozaki, K.; Yamaguchi-Shinozaki, K. (1997). "Gene Expression and Signal Transduction in Water-Stress Response". Plant Physiology. 115 (2): 327–334. doi:10.1104/pp.115.2.327. PMC   158490 . PMID   12223810.
  10. ↑ Chaves, M. M.; Flexas, J.; Pinheiro, C. (2009-02-01). "Photosynthesis under drought and salt stress: regulation mechanisms from whole plant to cell". Annals of Botany. 103 (4): 551–560. doi:10.1093/aob/mcn125. ISSN   0305-7364. PMC   2707345 . PMID   18662937.
  11. ↑ Kirschbaum, M. U. F. (1988). "Recovery of photosynthesis from water stress in Eucalyptus pauciflora-a process in two stages". Plant, Cell and Environment. 11 (8): 685–694. doi:10.1111/j.1365-3040.1988.tb01151.x.
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