Biotic stress
Biotic stress is
The damage caused by these various living and nonliving agents can appear very similar.
Agriculture
Biotic stressors are a major focus of agricultural research, due to the vast economic losses caused to cash crops. The relationship between biotic stress and plant yield affects economic decisions as well as practical development. The impact of biotic injury on crop yield impacts population dynamics, plant-stressor coevolution, and ecosystem nutrient cycling.[3]
Biotic stress also impacts
In history
Biotic stresses have had huge repercussions for humanity; an example of this is the
Today
Losses to pests and disease in crop plants continue to pose a significant threat to agriculture and food security. During the latter half of the 20th century, agriculture became increasingly reliant on synthetic chemical pesticides to provide control of pests and diseases, especially within the intensive farming systems common in the developed world. However, in the 21st century, this reliance on chemical control is becoming unsustainable. Pesticides tend to have a limited lifespan due to the emergence of resistance in the target pests, and are increasingly recognised in many cases to have negative impacts on biodiversity, and on the health of agricultural workers and even consumers.[7]
Tomorrow
Due to the implications of climate change, it is suspected that plants will have increased susceptibility to pathogens.
Effect on plant growth
Photosynthesis
Many biotic stresses affect photosynthesis, as chewing insects reduce leaf area and virus infections reduce the rate of photosynthesis per leaf area. Vascular-wilt fungi compromise the water transport and photosynthesis by inducing stomatal closure.[6][9]
Response to stress
Plants have co-evolved with their parasites for several hundred million years. This co-evolutionary process has resulted in the selection of a wide range of plant defences against microbial pathogens and herbivorous pests which act to minimise frequency and impact of attack. These defences include both physical and chemical adaptations, which may either be expressed constitutively, or in many cases, are activated only in response to attack. For example, utilization of high metal ion concentrations derived from the soil allow plants to reduce the harmful effects of biotic stressors (pathogens, herbivores etc.); meanwhile preventing the infliction of severe metal toxicity by way of safeguarding metal ion distribution throughout the plant with protective physiological pathways.[10] Such induced resistance provides a mechanism whereby the costs of defence are avoided until defense is beneficial to the plant. At the same time, successful pests and pathogens have evolved mechanisms to overcome both constitutive and induced resistance in their particular host species. In order to fully understand and manipulate plant biotic stress resistance, we require a detailed knowledge of these interactions at a wide range of scales, from the molecular to the community level.[7]
Inducible defense responses to insect herbivores
In order for a plant to defend itself against biotic stress, it must be able to differentiate between an abiotic and biotic stress. A plants response to herbivores starts with the recognition of certain chemicals that are abundant in the saliva of the herbivores. These compounds that trigger a response in plants are known as elicitors or herbivore-associated molecular patterns (HAMPs).[11] These HAMPs trigger signalling pathways throughout the plant, initiating its defence mechanism and allowing the plant to minimise damage to other regions. These HAMPs trigger signalling pathways throughout the plant, initiating its defence mechanism and allowing the plant to minimise damage to other regions. Phloem feeders, like aphids, do not cause a great deal of mechanical damage to plants, but they are still regarded as pests and can seriously harm crop yields. Plants have developed a defence mechanism using salicylic acid pathway, which is also used in infection stress, when defending itself against phloem feeders. Plants perform a more direct attack on an insects digestive system. The plants do this using proteinase inhibitors. These proteinase inhibitors prevent protein digestion and once in the digestive system of an insect, they bind tightly and specifically to the active site of protein hydrolysing enzymes such as trypsin and chymotrypsin.[11] This mechanism is most likely to have evolved in plants when dealing with insect attack.
Plants detect elicitors in the insects saliva. Once detected, a signal transduction network is activated. The presence of an elicitor causes an influx of Ca2+ ions to be released in to the cytosol. This increase in cytosolic concentration activates target proteins such as Calmodulin and other binding proteins. Downstream targets, such as phosphorylation and transcriptional activation of stimulus specific responses, are turned on by Ca2+ dependent protein kinases.[11] In Arabidopsis, over expression of the IQD1 calmodulin-binding transcriptional regulator leads to inhibitor of herbivore activity. The role of calcium ions in this signal transduction network is therefore important.
Calcium Ions also play a large role in activating a plants defensive response. When fatty acid amides are present in insect saliva, the
Inducible defense responses to pathogens
Plants are capable of detecting invaders through the recognition of non-self signals despite the lack of a
Both the pattern recognition immunity (PTI) and effector-triggered immunity (ETI) result from the upregulation of multiple defense mechanisms including defensive chemical signaling compounds.
Studies regarding the upregulation of defensive chemicals have confirmed the role of SA and JA in pathogen defense. In studies utilizing Arabidopsis mutants with the bacterial NahG gene, which inhibits the production and accumulation of SA, were shown to be more susceptible to pathogens than the wild-type plants. This was thought to result from the inability to produce critical defensive mechanisms including increased PR gene expression.[16][17] Other studies conducted by injecting tobacco plants and Arabidopsis with salicylic acid resulted in higher resistance of infection by the alfalfa and tobacco mosaic viruses, indicating a role for SA biosynthesis in reducing viral replication.[17][18] Additionally, studies performed using Arabidopsis with mutated jasmonic acid biosynthesis pathways have shown JA mutants to be at an increased risk of infection by soil pathogens.[16]
Along with SA and JA, other defensive chemicals have been implicated in plant viral pathogen defenses including abscisic acid (ABA), gibberellic acid (GA), auxin, and peptide hormones.[15] The use of hormones and innate immunity presents parallels between animal and plant defenses, though pattern-triggered immunity is thought to have arisen independently in each.[12]
Cross tolerance with abiotic stress
- Evidence shows that a plant undergoing multiple stresses, both abiotic and biotic (usually pathogen or herbivore attack), can produce a positive effect on plant performance, by reducing their susceptibility to biotic stress compared to how they respond to individual stresses. The interaction leads to a crosstalk between their respective hormone signalling pathways which will either induce or antagonize another restructuring genes machinery to increase tolerance of defense reactions.[19]
- Reactive oxygen species (ROS) are key signalling molecules produced in response to biotic and abiotic stress cross tolerance. ROS are produced in response to biotic stresses during the oxidative burst.[20]
- Dual stress imposed by ozone (O3) and pathogen affects tolerance of crop and leads to altered host pathogen interaction (Fuhrer, 2003). Alteration in pathogenesis potential of pest due to O3 exposure is of ecological and economical importance.[21]
- Tolerance to both biotic and abiotic stresses has been achieved. In maize, breeding programmes have led to plants which are tolerant to drought and have additional resistance to the parasitic weed Striga hermonthica.[22][23]
Remote sensing
The Agricultural Research Service (ARS) and various government agencies and private institutions have provided a great deal of fundamental information relating spectral reflectance and thermal emittance properties of soils and crops to their agronomic and biophysical characteristics. This knowledge has facilitated the development and use of various remote sensing methods for non-destructive monitoring of plant growth and development and for the detection of many environmental stresses that limit plant productivity. Coupled with rapid advances in computing and position locating technologies, remote sensing from ground-, air-, and space-based platforms is now capable of providing detailed spatial and temporal information on plant response to their local environment that is needed for site specific agricultural management approaches.[24] This is very important in today's society because with increasing pressure on global food productivity due to population increase, result in a demand for stress-tolerant crop varieties that has never been greater.
See also
- Abiotic stress – Stress on organisms caused by nonliving factors
- Biotic component– Community of living organisms together with the nonliving components of their environment
- List of beneficial weeds
References
- ^ a b c Flynn 2003.
- ^ Yadav 2012.
- ^ Peterson & Higley 2001.
- ^ Carris, Little & Stiles 2012.
- ^ Karim 2007.
- ^ a b c Flexas, Loreto & Medrano 2012.
- ^ a b Roberts 2013.
- ^ a b Garrett et al. 2006.
- .
- ^ Poschenrieder, Tolrà & Barceló 2006.
- ^ ISBN 9781605352558.
- ^ S2CID 205491561.
- PMID 19423812.
- ^ PMID 20471306.
- ^ S2CID 28385498.
- ^ S2CID 28317435.
- ^ PMID 19400653.
- .
- ^ Rejeb, Pastor & Mauch-Mani 2014.
- ^ Perez & Brown 2014.
- ^ Raju et al. 2015.
- ^ Atkinson & Urwin 2012.
- ^ Fuller, Lilley & Urwin 2008.
- ^ Pinter et al. 2003.
Sources
- Atkinson, N. J.; Urwin, P. E. (2012). "The interaction of plant biotic and abiotic stresses: from genes to the field". Journal of Experimental Botany. 63 (10): 3523–3543. PMID 22467407.
- Carris, L. M.; Little, C. R.; Stiles, C. M. (2012). "Introduction to Fungi". www.apsnet.org. doi:10.1094/PHI-I-2012-0426-01 (inactive 31 January 2024). Archived from the original on 2015-11-10. Retrieved 11 March 2016.)
{{cite journal}}
: CS1 maint: DOI inactive as of January 2024 (link - Flexas, J.; Loreto, F.; Medrano, H., eds. (2012). Terrestrial Photosynthesis In A Changing Environment: A Molecular, Physiological, and Ecological Approach. CUP. ISBN 978-0521899413.
- Flynn, P. (2003). "Biotic vs. Abiotic - Distinguishing Disease Problems from Environmental Stresses". ISU Entomology. Retrieved 16 May 2013.
- Fuller, V. L.; Lilley, C. J.; Urwin, P. E. (2008). "Nematode resistance". New Phytologist. 180 (1): 27–44. PMID 18564304.
- Garrett, K. A.; Dendy, S. P.; Frank, E. E.; Rouse, M. N.; Travers, S. E. (2006). "Climate Change Effects on Plant Disease: Genomes to Ecosystems" (PDF). Annual Review of Phytopathology. 44: 489–509. PMID 16722808.
- Karim, S. (2007). Exploring plant tolerance to biotic and abiotic stresses (PDF) (Thesis). ISBN 978-9157673572.
- Perez, I. B.; Brown, P. J. (2014). "The role of ROS signaling in cross-tolerance: from model to crop". Front. Plant Sci. 5: 754. PMID 25566313.
- Peterson, R. K. D.; Higley, L. G., eds. (2001). Biotic Stress and Yield Loss. CRC Press. ISBN 978-0849311451.
- Pinter, P. J.; Hatfield, J. L.; Schepers, J. S.; Barnes, E. M.; Moran, M. S.; Daughtry, C. S.T.; Upchurch, D. R. (2003). "Remote Sensing for Crop Management". Photogrammetric Engineering & Remote Sensing. 69 (6): 647–664. .
- Poschenrieder, C.; Tolrà, R.; Barceló, J. (2006). "Can metals defend plants against biotic stress?". Trends in Plant Science. 11 (6): 288–295. PMID 16697693.
- Raju, N. J.; Gossel, W.; Ramanathan, A.; Sudhakar, M., eds. (2015). Management of Water, Energy and Bio-resources in the Era of Climate Change: Emerging Issues and Challenges. S2CID 132165592.
- Rejeb, I. B.; Pastor, V.; Mauch-Mani, B. (2014). "Plant Responses to Simultaneous Biotic and Abiotic Stress: Molecular Mechanisms". Plants. 3 (4): 458–475. PMID 27135514.
- Roberts, M. (2013). "Preface: Induced Resistance to biotic stress". Journal of Experimental Botany. 64 (5): 1235–1236. PMID 23616991.
- Yadav, B. K. V. (2012). "Abiotic stress". forestrynepal.org. Archived from the original on 7 August 2016. Retrieved 3 December 2015.