Climate Change Influences the Interactive Effects of Simultaneous Impact of Abiotic and Biotic Stresses on Plants

Under natural conditions, the defense responses of plants exposed to combined abiotic and biotic stress factors, which can randomly interact with each other, are in many aspects different from the response induced by an individual stress. Predicted climatic changes through affecting these simultaneously occurring interactions might change the microclimate surrounding plants, plants’ susceptibility, the range of host microorganisms (i.e., symbionts or pathogens), and their simultaneous interaction with plants. The influence of climate change on interactions between environmental stresses and plants can lead to positive or negative impacts of one stress on the others and cause changes in strategies adopted by plants—either negative (i.e., susceptibility) or positive (i.e., tolerance)—thus causing modifications of primary and secondary metabolism of plants. Primary metabolism plays a key role in plants’ adaptive/defense response through the influence on the modulation of secondary metabolism and the activation of the host’s various defense mechanisms. Alterations in primary and secondary metabolism might include changes in the availability of nutrients, metabolically active compounds, or in carbon (C) and nitrogen (N) metabolism and C/N balance.