In nature plants seldom grow in isolation. Their growth and development are greatly influenced by abiotic and biotic factors to which they are continuously exposed. Unlike animals they are rooted in the soil, and consequently they cannot escape adverse environmental conditions in their vicinity (Fig. 32.1). Rather they have to develop the strategies to adapt themselves to the hostile conditions in order to survive and grow. Biotic interactions of plants are not always harmful but they can be beneficial too. Plant-pollinator interactions, rhizobia-legume interactions, or mycorrhizal interactions are examples of mutualism in which both the partners of the association are benefitted. In rhizobia-legume interactions, host plant provides ecological niche and nutrients which are required for the growth of prokaryotes, while the prokaryotes provide nitrogen to the host plant. Some plants are not able to excrete protons or organic acids in the soil required for uptake of nutrients like phosphates. They do so through symbiotic associations with mycorrhizal fungi. Associations, in which one of the partners is benefitted and the other one is not affected, are called commensalism. In some cases, the association may become beneficial as the benefitting partner may stimulate defense mechanism in the other organisms. There may also be harmful biotic interactions among plants and other organisms. These include interactions of plants with pathogens, with the plant pests and parasitic associations between the plants. Plant pathogens are the organisms that spend a part of their life cycle or complete their life cycle inside the plant. These include the microbial pathogen such as viruses, bacteria, or fungi. On the contrary, plant pests include the herbivores, such as insects, nematodes, or mammals which cause damage to plants by eating their vegetative tissue, fruits, or seeds (Fig. 32.2). It is interesting to note that plants growing in the wild rarely develop disease. However, domestication of economically important species leads to the development of monocultures, thereby resulting in genetic uniformity which makes them more susceptible to infections. Understanding the interactions of plants with their biotic environment greatly helps in reducing the use of agrochemicals which, in turn, would facilitate reduction in pollution and also in the cost of energy required for their production. Allelopathic interactions occur between plants growing nearby. Growth of some plants is inhibited because of chemicals produced by the adjacent plants which results in a sort of a chemical warfare. In this chapter plant’s interactions with biotic factors will be dealt with at physiological and molecular level.
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Suggested Further Readings
Alba JM, Allmann S, Glas JJ, Schimmel CJ, Spyropoulou EA, Stoops MV, Kant MR (2012) Induction and suppression of herbivore-induced indirect defenses. In: Witzany G, Baluska F (eds) Biocommunication of plants. Springer, New York, pp 197–212CrossRefGoogle Scholar
Engelberth J (2015) Plant resistance to insect herbivory. In: Witzany G, Baluska F (eds) Biocommunication of plants. Springer, New York, pp 303–326Google Scholar
Hammond KE, Jones JDG (2015) Responses to plant pathogens. In: Buchanan BB, Gruissem W, Jones RL (eds) Biochemistry and molecular biology of plants. Wiley Blackwell, UK, pp 984–1050Google Scholar
Smith AM, Coupland G, Dolan L, Harberd N, Martin C, Sablowski R, Amey A (2010) Interactions with other organisms. In: Plant biology. Garland Science, London, pp 499–572Google Scholar
Taiz L, Zeiger E, Moller IM, Murphy A (2015) Biotic interactions. In: Plant physiology and development, 6th edn. Sinauer Associates, Sunderland, pp 693–730Google Scholar