Adaptation Strategies to Improve the Resistance of Oilseed Crops to Heat Stress Under a Changing Climate: An Overview

Abstract

Temperature is one of the decisive environmental factors that is projected to increase by 1. 5°C over the next two decades due to climate change that may affect various agronomic characteristics, such as biomass production, phenology and physiology, and yield-contributing traits in oilseed crops. Oilseed crops such as soybean, sunflower, canola, peanut, cottonseed, coconut, palm oil, sesame, safflower, olive etc., are widely grown. Specific importance is the vulnerability of oil synthesis in these crops against the rise in climatic temperature, threatening the stability of yield and quality. The natural defense system in these crops cannot withstand the harmful impacts of heat stress, thus causing a considerable loss in seed and oil yield. Therefore, a proper understanding of underlying mechanisms of genotype-environment interactions that could affect oil synthesis pathways is a prime requirement in developing stable cultivars. Heat stress tolerance is a complex quantitative trait controlled by many genes and is challenging to study and characterize. However, heat tolerance studies to date have pointed to several sophisticated mechanisms to deal with the stress of high temperatures, including hormonal signaling pathways for sensing heat stimuli and acquiring tolerance to heat stress, maintaining membrane integrity, production of heat shock proteins (HSPs), removal of reactive oxygen species (ROS), assembly of antioxidants, accumulation of compatible solutes, modified gene expression to enable changes, intelligent agricultural technologies, and several other agronomic techniques for thriving and surviving. Manipulation of multiple genes responsible for thermo-tolerance and exploring their high expressions greatly impacts their potential application using CRISPR/Cas genome editing and OMICS technology. This review highlights the latest outcomes on the response and tolerance to heat stress at the cellular, organelle, and whole plant levels describing numerous approaches applied to enhance thermos-tolerance in oilseed crops. We are attempting to critically analyze the scattered existing approaches to temperature tolerance used in oilseeds as a whole, work toward extending studies into the field, and provide researchers and related parties with useful information to streamline their breeding programs so that they can seek new avenues and develop guidelines that will greatly enhance ongoing efforts to establish heat stress tolerance in oilseeds.

Keywords: CRISPR/Cas9 technology; antioxidants; heat stress; oilseeds; omics technology; signaling; smart technologies; tolerance.

Figure 1

Plant thermo-sensors and main signal transduction pathways implicated in heat stress response and thermo-tolerance (modified from Bokszczanin and Fragkostefanakis, 2013).

Figure 2

Membrane heat sensors and signal transduction pathways through various receptors across the plasma membrane.

Figure 3

Impact of heat stress on physiological, biochemical, growth, and yield responses in plants.

Figure 4

Impact of heat stress on photosynthesis and the photosynthetic system (conceived from Nadeem et al., 2018).

Figure 5

ABA signaling pathway in oilseed crops.

Figure 6

Ethylene signaling pathway under heat stress.

Figure 7

Schematic diagram to show the ASC-GHS cycle to scavenge ROS.

Figure 8

Integration of omics approaches (genomics, transcriptomics, proteomics, metabolomics, and ionomics) for crop improvement (modified form of Zargar et al., 2016).

Figure 9

Phenomics and its integration with other omics approaches (adopted from Deshmukh et al., 2014).

Figure 10

Effect of heat stress and application of plant growth regulators on phenological, physiological, and biochemical properties of oilseed plants.