Morphological and Physiological Plant Responses to Drought Stress inThymus citriodorus

Abstract

Water availability is considered as a determinant factor that affects plant growth. The commercial medicinal values of an aromatic plant rely on the presence of secondary metabolites that are affected under water shortage. Two-year-oldThymus citriodorusplants were subjected to different polyethylene glycol (PEG-6000) levels (0, 2%, and 4%) under greenhouse condition. PEG treatment lasted for 15 days. Thyme plant showed a morphological drought avoidance mechanism by maintaining the root system development through shoot fresh weight reduction resulting in promoted root absorption capacity and sustained plant growth. Moreover, stressed plants were able to maintain water use efficiency and root : shoot ratio suggesting a strong relation between root water uptake and water use saving strategies. Furthermore, thyme plants reduced tissue dehydration through stomatal closure and improved root water uptake. Content of volatile oil constituents of geraniol and diisobutyl phthalate increased upon drought stress while pseudophytol was reduced. Unexpectedly, thymol was not reported as a main oil element under either control or mild stress condition, while it was increased upon high drought stress in measure of 4.4%. Finally, carvacrol significantly accumulated under high drought stress (+31.7%) as compared to control plants.

Comprehensive Screening of Some West and Central African Sesame Genotypes for Drought Resistance Probing by Agromorphological, Physiological, Biochemical and Seed Quality Traits

“…In rice, it was reported that rolled leaves transpire 41 per cent less water than did the unrolled ones [34] and then help genotypes to better sustain drought. More importantly, the drought resistant genotypes WC17, WC18 and WC14 increased the R/S ratio under drought which is an important indicator of drought avoidance [35]. This is achieved by maintaining the root system development through shoot weight reduction resulting in promoted root absorption.…”

“…This is achieved by maintaining the root system development through shoot weight reduction resulting in promoted root absorption. Availability of water thus improves maintenance of cell turgor and support aboveground tissue growth during water stress [35].…”

Fungal Endophytes Exert Positive Effects on Colobanthus quitensis Under Water Stress but Neutral Under a Projected Climate Change Scenario in Antarctica

“…The stress occurs when soil water availability is reduced to critical levels that stop growth and normal functioning of plants (Ramakrishna and Ravishankar, 2011). In response to drought, however, plants can display a suite of physiological, biochemical, and morphological adjustments to diminish the negative impact of the stress on fitness (Potters et al, 2007;Atkinson and Urwin, 2012;Osakabe et al, 2013;Tátrai et al, 2016). Accumulating recent research suggests that these phenotypic adjustments that allow plants to face stressful situations may be positively modulated by symbiotic microorganisms (Dupont et al, 2015;Wani et al, 2015).…”

Methodology of Drought Stress Research: Experimental Setup and Physiological Characterization

“…Therefore, a complex multi-level regulatory network, controlling plant adaptive responses to drought stress, is required. Studies of such responses to water deficit such as stomata closure, expression of stress-specific genes, accumulation of osmolytes and up-regulation of antioxidant systems recently made considerable progress [17,35,36,37,38]. It was shown, that the mechanisms, underlying stress-resistance, are crucial for plant survival, and are associated with significant changes in the patterns of metabolites and proteins [10,15,35].…”