Injury in plants

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Injury in plants is damage caused by other organisms or by the non-living (abiotic) environment to plants. Animals that commonly cause injury to plants include insects, mites, nematodes, and herbivorous mammals; damage may also be caused by plant pathogens including fungi, bacteria, and viruses. Abiotic factors that can damage plants include heat, freezing, flooding, lightning, ozone gas, and pollutant chemicals.

Contents

Plants respond to injury by signalling that damage has occurred, by secreting materials to seal off the damaged area, by producing antimicrobial chemicals, and in woody plants by regrowing over wounds.

Factors

Biotic

Pieris brassicae caterpillars damaging a Brassica crop Large White (Pieris brassicae) Caterpillars, Omagh - geograph.org.uk - 3664347.jpg
Pieris brassicae caterpillars damaging a Brassica crop

Animals that commonly cause injury to plants include pests such as insects, mites, and nematodes. These variously bite or abrade plant parts such as leaves, stems, and roots, or as is common among the true bugs, pierce the plant's surface and suck plant juices. The resulting injuries may admit plant pathogens such as bacteria and fungi, which may extend the injury. [1] Caterpillar larvae of agricultural pests such as cabbage white butterflies (Pieridae) can completely defoliate Brassica crops. [2] Molluscs such as snails graze on plants including grasses and forbs, abrading them with their rasp-like radula; they can inflict substantial damage to crops. [3] Grazing mammals including livestock such as cattle, too, bite off or break parts of plants including grasses, forbs, and forest trees, causing injury, and again, potentially admitting pathogens. [4]

Abiotic

Oak tree split by lightning Oak tree struck by lightning - geograph.org.uk - 4084083.jpg
Oak tree split by lightning

Abiotic factors that can damage plants include heat, freezing, flooding, lightning strikes, ozone gas, and pollutant chemicals.

Heat can kill any plant, given a sufficient temperature. Alpine plants tend to die at around 47 Celsius; temperate plants at around 51 Celsius; and tropical plants at nearly 58 Celsius: but there is some overlap depending on species. Similarly among cereal crops, temperate barley and oat die at around 49 Celsius, but tropical maize at 55 Celsius. [5]

Freezing affects plants variously, according to each species' ability to resist frost damage. Many forbs, including many garden flowers, are tender with little tolerance to frost, and die or are seriously damaged when frozen. Many woody plants are able to supercool, with tough buds and stems containing molecules that lower the freezing point or help to prevent the nucleation of ice crystals, and cell walls that mechanically protect cells against freezing. [6]

Flooding of soil quickly kills or injures many plants. The leaves become yellow (chlorosis) and die, progressively up the stem, within about five days after the roots are flooded. The roots lose the ability to absorb water and nutrients. [7]

Lightning strikes kill or injure plants, from root crops like beet and potato, which are instantly cooked in the ground, to trees such as coconut, through effects such as sudden heat and pressure shock waves created when water inside the plant flashes to steam. This can rupture stems and scorch any plant parts. [8]

Ozone, a gas, causes injury to leaves at concentrations from as little as 0.1 part per million in the atmosphere, such as may be found in or near large cities. [9] It is one of many pollutant chemicals that can damage plants. [10]

Plant responses

Wound healing in Quercus robur. Two branches, cut at different times, have regrown branch collars, but the wood inside has become wet and is being rotted by fungi. Wound healing in Quercus robur.jpg
Wound healing in Quercus robur . Two branches, cut at different times, have regrown branch collars, but the wood inside has become wet and is being rotted by fungi.

Plants respond to injury by signalling that damage has occurred, [11] by secreting materials to seal off the damaged area, [12] by producing antimicrobials to limit the spread of pathogens, [13] and in some woody plants by regrowing over the wound. [14]

Signalling

Plants produce chemicals at the injury site that signal the presence of damage and may help to reduce further damage. The chemicals involved depend to some extent on the plant species, though several of them are shared among species; and the signals given depend on the cause of the injury. Plants injured by spider mites release volatile chemicals that attract predatory mites, serving to reduce the attack on the plants. As another example, maize plants damaged by the caterpillars of noctuid moths release a mixture of terpenoid substances which attract the parasitoid wasp Cotesia marginiventris , which kills caterpillars. [11] [15] Many plants give off such herbivory-induced signals. [16]

Wound occlusion

Hinoki cypress scar of cut branch, secreting resin in response to the injury Hinoki Cypress branch wound resin.jpg
Hinoki cypress scar of cut branch, secreting resin in response to the injury

Plants secrete a variety of chemicals to help seal off damaged areas. For example, the grape vine Vitis vinifera is able to block the xylem water-transport tubes in its stems using the chemical tylose in summertime, and gels in wintertime when the plant is dormant. Tylose helps to prevent pathogens such as wood-rotting fungi and the bacterium Xylella fastidiosa from spreading through the plant: the chemical is produced as a response both to the bacterium and to mechanical damage such as viticultural pruning. [12]

Chemical defence

Many woody plants produce resins [17] and antimicrobial chemicals to limit the spread of pathogens after an injury. [13] [18]

Wound healing

Many woody plants regrow around injuries, such as those caused by pruning. In time, such regrowth often completely covers the damaged area as the cambium growth layer produces new tissues. Well-pruned trees with undamaged branch collars often recover well, where poorly-pruned trees rot below the wound. [14] [19] [20]

See also

Related Research Articles

<span class="mw-page-title-main">Plant pathology</span> Scientific study of plant diseases

Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens and environmental conditions. Plant pathology involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.

<span class="mw-page-title-main">Pest (organism)</span> Organism harmful to humans/our concerns

A pest is any organism harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environment for their own purposes and are intolerant of other creatures occupying the same space when their activities impact adversely on human objectives. Thus, an elephant is unobjectionable in its natural habitat but a pest when it tramples crops.

<i>Botrytis cinerea</i> Species of fungus

Botrytis cinerea is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or "gray mold".

<span class="mw-page-title-main">Endophyte</span> Endosymbiotic bacterium or fungus

An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth and nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought, and decrease biotic stresses by enhancing plant resistance to insects, pathogens and herbivores. Although endophytic bacteria and fungi are frequently studied, endophytic archaea are increasingly being considered for their role in plant growth promotion as part of the core microbiome of a plant.

An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals are used against fungi. They can also be classified according to their function. The use of antimicrobial medicines to treat infection is known as antimicrobial chemotherapy, while the use of antimicrobial medicines to prevent infection is known as antimicrobial prophylaxis.

<span class="mw-page-title-main">Air purifier</span> Device that removes contaminants from the air in a room

An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.

<span class="mw-page-title-main">Bark beetle</span> Subfamily of beetles

A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the term "bark beetle" refers to the fact that many species feed in the inner bark (phloem) layer of trees, the subfamily also has many species with other lifestyles, including some that bore into wood, feed in fruit and seeds, or tunnel into herbaceous plants. Well-known species are members of the type genus Scolytus, namely the European elm bark beetle S. multistriatus and the large elm bark beetle S. scolytus, which like the American elm bark beetle Hylurgopinus rufipes, transmit Dutch elm disease fungi (Ophiostoma). The mountain pine beetle Dendroctonus ponderosae, southern pine beetle Dendroctonus frontalis, and their near relatives are major pests of conifer forests in North America. A similarly aggressive species in Europe is the spruce ips Ips typographus. A tiny bark beetle, the coffee berry borer, Hypothenemus hampei is a major pest on coffee plantations around the world.

<span class="mw-page-title-main">Oak wilt</span> Plant disease

Oak wilt is a fungal disease caused by the organism Bretziella fagacearum that threatens Quercus spp. The disease is limited to the eastern half of the United States; first described in the 1940s in the Upper Mississippi River Valley. The pathogen penetrates xylem tissue, preventing water transport and causing disease symptoms. Symptoms generally consist of leaf discoloration, wilt, defoliation, and death. The disease is dispersed by insect vectors and to adjacent trees through underground root networks. However, human spread is the most consequential dispersal method. Moving firewood long distances can potentially transport diseases and invasive species.

<span class="mw-page-title-main">Juglone</span> Chemical produced by walnut trees

Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is a phenolic organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles. It is an isomer of lawsone, which is the active dye compound in the henna leaf.

<i>Pseudomonas syringae</i> Species of bacterium

Pseudomonas syringae is a rod-shaped, Gram-negative bacterium with polar flagella. As a plant pathogen, it can infect a wide range of species, and exists as over 50 different pathovars, all of which are available to researchers from international culture collections such as the NCPPB, ICMP, and others.

<span class="mw-page-title-main">Branch collar</span> German term: a part of a tree

A branch collar is the "shoulder" between the branch and trunk of woody plants; the inflammation formed at the base of the branch is caused by annually overlapping trunk tissue. The shape of the branch collar is due to two separate growth patterns, initially the branch grows basipetally, followed by seasonal trunk growth which envelops the branch.

<i>Neonectria ditissima</i> Species of fungus

Neonectria ditissima is a fungal plant pathogen. It causes cankers that can kill branches of trees by choking them off. Apple and beech trees are two susceptible species.

Soil solarization is a non-chemical environmentally friendly method for controlling pests using solar power to increase the soil temperature to levels at which many soil-borne plant pathogens will be killed or greatly weakened. Soil solarization is used in warm climates on a relatively small scale in gardens and organic farms. Soil solarization weakens and kills fungi, bacteria, nematodes, and insect and mite pests along with weeds in the soil by mulching the soil and covering it with a tarp, usually with a transparent polyethylene cover to trap solar energy. This energy causes physical, chemical, and biological changes in the soil community. Soil solarization is dependent upon time, temperature, and soil moisture. It may also be described as methods of decontaminating soil or creating suppressive soils by the use of sunlight.

<span class="mw-page-title-main">Forest dieback</span> Stand of trees losing health and dying

Forest dieback is a condition in trees or woody plants in which peripheral parts are killed, either by pathogens, parasites or conditions like acid rain, drought, and more. These episodes can have disastrous consequences such as reduced resiliency of the ecosystem, disappearing important symbiotic relationships and thresholds. Some tipping points for major climate change forecast in the next century are directly related to forest diebacks.

Mal secco is a disease caused by the conidia-producing fungal plant pathogen Phoma tracheiphila. It mainly causes disease to citrus trees in the Mediterranean. In particular it causes damage to lemon trees in the Mediterranean basin. The plant pathogen, Phoma tracheiphila, is rain- and wind-disseminated.

Biotic stress is stress that occurs as a result of damage done to an organism by other living organisms, such as bacteria, viruses, fungi, parasites, beneficial and harmful insects, weeds, and cultivated or native plants. It is different from abiotic stress, which is the negative impact of non-living factors on the organisms such as temperature, sunlight, wind, salinity, flooding and drought. The types of biotic stresses imposed on an organism depend the climate where it lives as well as the species' ability to resist particular stresses. Biotic stress remains a broadly defined term and those who study it face many challenges, such as the greater difficulty in controlling biotic stresses in an experimental context compared to abiotic stress.

<span class="mw-page-title-main">Plant disease resistance</span> Ability of a plant to stand up to trouble

Plant disease resistance protects plants from pathogens in two ways: by pre-formed structures and chemicals, and by infection-induced responses of the immune system. Relative to a susceptible plant, disease resistance is the reduction of pathogen growth on or in the plant, while the term disease tolerance describes plants that exhibit little disease damage despite substantial pathogen levels. Disease outcome is determined by the three-way interaction of the pathogen, the plant and the environmental conditions.

Green leaf volatiles (GLV) are organic compounds released by plants. Some of these chemicals function as signaling compounds between either plants of the same species, of other species, or even different lifeforms like insects.

Chemical defenses in <i>Cannabis</i> Defense of Cannabis plant from pathogens

Cannabis (/ˈkænəbɪs/) is commonly known as marijuana or hemp and has two known strains: Cannabis sativa and Cannabis indica, both of which produce chemicals to deter herbivory. The chemical composition includes specialized terpenes and cannabinoids, mainly tetrahydrocannabinol (THC), and cannabidiol (CBD). These substances play a role in defending the plant from pathogens including insects, fungi, viruses and bacteria. THC and CBD are stored mostly in the trichomes of the plant, and can cause psychological and physical impairment in the user, via the endocannabinoid system and unique receptors. THC increases dopamine levels in the brain, which attributes to the euphoric and relaxed feelings cannabis provides. As THC is a secondary metabolite, it poses no known effects towards plant development, growth, and reproduction. However, some studies show secondary metabolites such as cannabinoids, flavonoids, and terpenes are used as defense mechanisms against biotic and abiotic environmental stressors.

<span class="mw-page-title-main">Injury</span> Wound caused by an external source

Injury is physiological damage to the living tissue of any organism, whether in humans, in other animals, or in plants.

References

  1. ↑ Tarr, S. A. J. (1972). "Plant injury due to insects, mites, nematodes and other pests". Principles of Plant Pathology. London: Macmillan. pp. 126–137. doi:10.1007/978-1-349-00355-6_9. ISBN   978-1-349-00357-0.
  2. ↑ Theunissen, J.; Ouden, H.; Wit, A. K. H. (1985). "Feeding capacity of caterpillars on cabbage, a factor in crop loss assessment". Entomologia Experimentalis et Applicata. 39 (3). Wiley: 255–260. Bibcode:1985EEApp..39..255T. doi:10.1111/j.1570-7458.1985.tb00467.x. ISSN   0013-8703. S2CID   86725952.
  3. ↑ Silva, Oliveira; Teresa, Maria (1992). "Effects of mollusc grazing on the development of grassland species". Journal of Vegetation Science. 3 (2). Wiley: 267–270. Bibcode:1992JVegS...3..267S. doi:10.2307/3235689. ISSN   1100-9233. JSTOR   3235689.
  4. ↑ Cappelli, Seraina Lisa; Koricheva, Julia (2 July 2021). "Interactions between mammalian grazers and plant pathogens: an elephant in the room?". New Phytologist. 232 (1). Wiley: 8–10. doi:10.1111/nph.17533. ISSN   0028-646X. PMID   34213785. S2CID   235708670.
  5. ↑ Smillie, R.M.; Nott, R. (1979). "Heat Injury in Leaves of Alpine, Temperate and Tropical Plants". Functional Plant Biology. 6 (1). CSIRO Publishing: 135. doi:10.1071/pp9790135. ISSN   1445-4408.
  6. ↑ Burke, M. J.; Gusta, L. V.; Quamme, H. A.; Weiser, C. J.; Li, P. H. (1976). "Freezing and Injury in Plants". Annual Review of Plant Physiology. 27 (1). Annual Reviews: 507–528. doi:10.1146/annurev.pp.27.060176.002451. ISSN   0066-4294.
  7. ↑ Kramer, Paul J. (1 October 1951). "Causes of Injury to Plants Resulting from Flooding of the Soil". Plant Physiology. 26 (4). Oxford University Press: 722–736. doi:10.1104/pp.26.4.722. ISSN   0032-0889. PMC   437542 . PMID   16654407.
  8. ↑ Nelson, Scot C. (July 2008). "Lightning Injury to Plants" (PDF). Plant Disease (PD-40).
  9. ↑ Hill, A. C.; Pack, M. R.; Treshow, M. (1961). "Plant injury induced by ozone". Phytopathology. 51. OSTI   5518148.
  10. ↑ Heath, R. L. (1980). "Initial Events in Injury to Plants by Air Pollutants". Annual Review of Plant Physiology. 31 (1). Annual Reviews: 395–431. doi:10.1146/annurev.pp.31.060180.002143. ISSN   0066-4294.
  11. 1 2 Turlings, Ted C.; Tumlinson, James H. (1992). "Systemic release of chemical signals by herbivore-injured corn". Proceedings of the National Academy of Sciences. 89 (17): 8399–8402. Bibcode:1992PNAS...89.8399T. doi: 10.1073/pnas.89.17.8399 . PMC   49926 . PMID   11607325.
  12. 1 2 Sun, Qiang; Rost, Thomas L.; Matthews, Mark A. (2008). "Wound-induced vascular occlusions in Vitis vinifera (Vitaceae): Tyloses in summer and gels in winter1". American Journal of Botany. 95 (12). Wiley: 1498–1505. doi:10.3732/ajb.0800061. ISSN   0002-9122. PMID   21628157.
  13. 1 2 Shigo, Alex L. (1985). "Compartmentalization of Decay in Trees". Scientific American. 252 (4): 96–103. Bibcode:1985SciAm.252d..96S. doi:10.1038/scientificamerican0485-96. hdl: 2027/uva.x002416568 . ISSN   0036-8733.
  14. 1 2 Shigo, Alex L. (1985). "How tree branches are attached to trunks". Canadian Journal of Botany. 63 (8): 1391–1401. doi:10.1139/b85-193.
  15. ↑ Harris, Christina M.; Ruberson, John R.; Meagher, Robert; Tumlinson, James H. (1 April 2012). "Host Suitability Affects Odor Association in Cotesia marginiventris: Implications in Generalist Parasitoid Host-Finding". Journal of Chemical Ecology. 38 (4): 340–347. doi:10.1007/s10886-012-0095-9. ISSN   1573-1561. PMID   22438015. S2CID   254650043 . Retrieved 15 July 2022.
  16. ↑ Wu, J.; Baldwin, I.T. (2009). "Herbivory-induced signalling in plants: Perception and action". Plant Cell Environment. 32 (9): 1161–1174. doi: 10.1111/j.1365-3040.2009.01943.x . PMID   19183291.
  17. ↑ "Resins". www.fs.fed.us.
  18. ↑ González-Lamothe, Rocío; Mitchell, Gabriel; Gattuso, Mariza; Diarra, Moussa; Malouin, François; Bouarab, Kamal (31 July 2009). "Plant Antimicrobial Agents and Their Effects on Plant and Human Pathogens". International Journal of Molecular Sciences. 10 (8). MDPI AG: 3400–3419. doi: 10.3390/ijms10083400 . ISSN   1422-0067. PMC   2812829 . PMID   20111686.
  19. ↑ O'Hara, Kevin L. (2007). "Pruning Wounds and Occlusion: A Long-Standing Conundrum in Forestry". Journal of Forestry. 105 (3): 131–138. doi:10.1093/jof/105.3.131. S2CID   10075580.
  20. ↑ "Tree pruning guide". US Forest Service for the US Department of Agriculture. Archived from the original on April 26, 2007. Features a diagram of the branch collar.
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