Abiotic Stress in Crop Production

Abstract

The vast majority of agricultural land undergoes abiotic stress that can significantly reduce agricultural yields. Understanding the mechanisms of plant defenses against stresses and putting this knowledge into practice is, therefore, an integral part of sustainable agriculture. In this review, we focus on current findings in plant resistance to four cardinal abiotic stressors-drought, heat, salinity, and low temperatures. Apart from the description of the newly discovered mechanisms of signaling and resistance to abiotic stress, this review also focuses on the importance of primary and secondary metabolites, including carbohydrates, amino acids, phenolics, and phytohormones. A meta-analysis of transcriptomic studies concerning the model plant Arabidopsis demonstrates the long-observed phenomenon that abiotic stressors induce different signals and effects at the level of gene expression, but genes whose regulation is similar under most stressors can still be traced. The analysis further reveals the transcriptional modulation of Golgi-targeted proteins in response to heat stress. Our analysis also highlights several genes that are similarly regulated under all stress conditions. These genes support the central role of phytohormones in the abiotic stress response, and the importance of some of these in plant resistance has not yet been studied. Finally, this review provides information about the response to abiotic stress in major European crop plants-wheat, sugar beet, maize, potatoes, barley, sunflowers, grapes, rapeseed, tomatoes, and apples.

Keywords: abiotic stress; cold stress; crop; drought; heat stress; metabolites; phytohormones; salinity.

Figure 5

Relative predicted subcellular distribution of stress-responsive gene products calculated for each compartment using the online tool SUBA5 [218]. Data for the analysis were obtained from the Expression Atlas database [203]. (A) The genes upregulated by a specific stress are marked as (+) and those downregulated by a specific stress are marked as (-). The bars represent the subcellular distribution of stress-responsive proteins based on the AGI list of stress-regulated genes compared to the HCM list; hits are identified and summed per compartment. (B) Heat-stress downregulated genes with localization to the Golgi and their function. The interactions were visualized by String [221].

Figure 1

Locations of recorded extreme weather conditions in Europe and the number of published works focusing on abiotic stress in crops. (A) Weather conditions recorded by the German Weather Service from October 2021 to February 2022 and March 2022 to July 2022 (Deutscher Wetterdienst, 2022, [15]). The heat or cold wave is a period of at least one week with temperature anomalies (exceeding +6 °C over or −6 °C below the average temperature during the reference period 1981–2010). Panel 1A was adapted from an original map image made by Maix, Wikimedia Commons, distributed under a CC SA 3.0 License. (B) The number of publications focusing on a specific crop and abiotic stress in the last 13 years. The data were obtained from the Clarivate Web of Science database based on the methodology detailed in Supplementary Materials S1.

Figure 2

The most important crops produced in Europe in 2021. Data were obtained from FAOSTAT [8]. (A) The pie chart represents the percentage of various crops under production in Europe in 2021. (B) The main countries in Europe that produce the selected crops. The color intensity corresponds to the contribution of individual states to overall production in Europe. The color coding in the legend was sorted from top to bottom according to the amount of production of individual crops. Hatched rectangles in the color legend indicate crop production not used in the figure. Panel 2B was prepared using maps from www.mapchart.net (accessed on 17 January 2023), distributed under a CC SA 4.0 License.

Figure 3

Abiotic stress signaling. Image represents novel mechanisms in abiotic stress signaling reviewed in corresponding sections.

Figure 4

Visualization of groups of genes found in response to abiotic stressors. Data based on Arabidopsis expression profiles found in the Expression Atlas database [203]. Since plants are sensitive to stress with respect to the developmental stage, our analysis included only those works that met the following criteria: (1) involved the model plant Arabidopsis thaliana, (2) seedling stage, and (3) application of one stress. In total, the database included 11 transcriptional studies for further analyses (2 studies of heat-responsive transcriptome [204,205], 3 studies of cold-responsive transcriptome [206,207,208], 3 studies of drought-responsive transcriptome [209,210,211], and 3 studies of salt-responsive transcriptome [204,212,213]). Details of the analysis are summarized in Supplementary Materials S2. Circles represent genes (red, upregulated; blue, downregulated; yellow, inverse response for different stresses). Squares represent stress treatments. Genes responsive to single abiotic stress are marked by one square, with the color corresponding to the stress (red, heat; orange, drought/low water potential; green, salinity; violet, cold). Genes responsive to several stressors are visualized by clusters marked with corresponding squares that represent all stress modulators. The image was prepared in DiVenn 1.2 [214].

Figure 6

Functional groups of genes with similar stress regulation in at least three abiotic stresses (identified in Figure 4): (A) 222 genes upregulated in at least 3 stresses; (B) 197 genes downregulated in at least 3 stresses. Visualization was prepared using proteomaps [222].

Figure 7

Functional annotations of common genes with changed regulation during stress crosstalk (heat, cold, drought, salinity; identified in Figure 4): (A) Protein classes represented in 38 common genes upregulated during stress crosstalk. (B) Protein classes represented in 11 common genes downregulated during stress crosstalk [240].

Figure 8

Role of phytohormones in plant stress response. Hormones with an overall positive effect are visualized by blue ovals. Hormones visualized by yellow ovals have been shown to have positive and negative effects on plant stress resistance in different studies. GAs visualized by red ovals mainly increase sensitivity to abiotic stress. More details about the function of hormones in stress responses in crops are shown in Table 3.