The Potential of the Synthetic Strigolactone Analogue GR24 for the Maintenance of Photosynthesis and Yield in Winter Wheat under Drought: Investigations on the Mechanisms of Action and Delivery Modes

Abstract

Strigolactones (SLs) have been implicated in many plant biological and physiological processes, including the responses to abiotic stresses such as drought, in concert with other phytohormones. While it is now clear that exogenous SLs may help plants to survive in harsh environmental condition, the best, most effective protocols for treatment have not been defined yet, and the mechanisms of action are far from being fully understood. In the set of experiments reported here, we contrasted two application methods for treatment with a synthetic analog of SL, GR24. A number of morphometric, physiological and biochemical parameters were measured following foliar application of GR24 or application in the residual irrigation water in winter wheat plants under irrigated and drought stress conditions. Depending on the concentration and the method of GR24 application, differentiated photosynthesis and transpiration rate, stomatal conductance, leaf water potential, antioxidant enzyme activities and yield in drought conditions were observed. We present evidence that different methods of GR24 application led to increased photosynthesis and yield under stress by a combination of drought tolerance and escape factors, which should be considered for future research exploring the potential of this new family of bioactive molecules for practical applications.

Plants’ Physio-Biochemical and Phyto-Hormonal Responses to Alleviate the Adverse Effects of Drought Stress: A Comprehensive Review

“…Gibberellic acids (GAs) (tetracyclic diterpenoid carboxylic acid) can enhance plant growth and development in a different stage of the life cycle by boosting the cell division and elongation [199]. The most bioactive versions of the other GAs generated by plants are GA1 and Gas [200]. The GAs hormone is related to drought stress tolerance and is associated with seed germination, stem elongation, and reproductive development in the rice (Oryza sativa L.) plant [201].…”

Strigolactones Modulate Cellular Antioxidant Defense Mechanisms to Mitigate Arsenate Toxicity in Rice Shoots

“…SLs positively regulate plant height, leaf senescence, stem thickness, root hair elongation and primary root length, whereas they negatively affect shoot gravitropism and branching, adventitious rooting and lateral root development under normal growth conditions [1,7]. Various loss-of-function studies have used SL-related mutants and synthetic GR24 to demonstrate that SLs played crucial regulatory roles in plant responses to environmental perturbations [10][11][12][13]. For example, SLdeficient Arabidopsis (Arabidopsis thaliana) and rice mutants, and SL-depleted transgenic Lotus japonicus and tomato (Solanum lycopersicum) lines showed higher susceptibility to drought than their respective wild-type (WT) plants [13][14][15][16].…”

“…For example, SLdeficient Arabidopsis (Arabidopsis thaliana) and rice mutants, and SL-depleted transgenic Lotus japonicus and tomato (Solanum lycopersicum) lines showed higher susceptibility to drought than their respective wild-type (WT) plants [13][14][15][16]. Foliar application of GR24 alleviated the deleterious effects of several abiotic stresses, including low light stress in tomato, drought in wheat (Triticum aestivum) and salinity in rice [12,17,18]. SL-mediated positive effects on plant tolerance to abiotic stresses mainly pertain to the regulation of various physiological and biochemical processes, including photosynthetic efficiency, leaf senescence, cell wall biogenesis, stomatal closure, flavonoid production, antioxidant defense and nutrient homeostasis [1].…”

Strigolactones as a hormonal hub for the acclimation and priming to environmental stress in plants

“…of NO during salt stress is reduced, suggesting that strigolactones are necessary for the NO-induced protective response to salt stress (H. Liu, Li, et al, 2022). A similar positive correlation between strigolactones and drought tolerance via increased antioxidant activity was highlighted in winter wheat (Sedaghat et al, 2017(Sedaghat et al, , 2021 and Medicago sativa (Y. Yang et al, 2022).…”