Methodology of Drought Stress Research: Experimental Setup and Physiological Characterization

Abstract

Drought is one of the major stress factors affecting the growth and development of plants. In this context, drought-related losses of crop plant productivity impede sustainable agriculture all over the world. In general, plants respond to water deficits by multiple physiological and metabolic adaptations at the molecular, cellular, and organism levels. To understand the underlying mechanisms of drought tolerance, adequate stress models and arrays of reliable stress markers are required. Therefore, in this review we comprehensively address currently available models of drought stress, based on culturing plants in soil, hydroponically, or in agar culture, and critically discuss advantages and limitations of each design. We also address the methodology of drought stress characterization and discuss it in the context of real experimental approaches. Further, we highlight the trends of methodological developments in drought stress research, i.e., complementing conventional tests with quantification of phytohormones and reactive oxygen species (ROS), measuring antioxidant enzyme activities, and comprehensively profiling transcriptome, proteome, and metabolome.

Transcriptome Analysis of Drought-Resistant and Drought-Sensitive Sorghum (Sorghum bicolor) Genotypes in Response to PEG-Induced Drought Stress

“…To screen for drought resistance at the seedling stage the root length of seven sorghum genotypes was evaluated in the presence and absence of 20% PEG, which has been extensively used to induce water deficit in plants in a controlled manner [4,[33][34][35]. The data for the two most drought-resistant genotypes (BTx623 [DR1] and SC56 [DR2]) and the two most drought-sensitive genotypes (Tx-7000 [DS1] and PI-482662 [DS2]) are presented in Figure 1.…”

“…It is the most common cause of food shortage in many countries [2] where it has caused over $29 billion in losses between 2005 and 2015 [3]. Plants use three main strategies (drought escape, drought avoidance, and drought tolerance) to survive under drought stress (reviewed in [4]). To cope with drought stress, plants reprogram a wide range of responses at the molecular, biochemical and physiological levels [5].…”

“…To accomplish this, we performed a transcriptomic analysis of gene expression in two drought-resistant and two drought-sensitive sorghum cultivars in response to polyethylene glycol (PEG)-induced drought stress in aqueous cultures. Although PEG has been widely used to simulate drought stress [4,[33][34][35] other soil-based approaches involving the withholding of water gradually or completely stopping of watering plants, and PEG-infused agar plates have also been used [4]. This study expands on the previous sorghum transcriptome studies [26][27][28] by analyzing the expression of all annotated sorghum genes [36] and identifying genes that are associated with drought resistance at the seedling stage.…”

Adapting Cereal Grain Crops to Drought Stress: 2020 and Beyond

“…A decrease in water inputs into an agro/ecosystem over time that is sufficient to cause soil water deficit (SWD) is often termed drought, and this encompasses various forms such as rainfall anomalies, irrigation failure, seasonal or annual dry spells [16]. In agricultural context, drought signifies a period of below-average precipitation when the available soil water in the plant rhizosphere drops beyond the thresholds for efficient growth and biomass production [17]. The resultant oxidative stress emanating from such SWD is dubbed drought stress.…”

“…To protect themselves against ROS induced oxidative stress and photo inhibition, plants activate an efficient antioxidant (enzymatic and non-enzymatic) defense system [17,18,21,41]. Enzymatic antioxidant enzymes include superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and glutathione S-transferase (GST) among others.…”