Physiological and Proteomic Responses of Pitaya to PEG-Induced Drought Stress

Abstract

Pitaya (Hylocereus polyrhizus L.) is highly tolerant to drought stress. Elucidating the response mechanism of pitaya to drought will substantially contribute to improving crop drought tolerance. In the present study, the physiological and proteomic responses of the pitaya cultivar ‘Zihonglong’ were compared between control seedlings and seedlings exposed to drought stress (−4.9 MPa) induced by polyethylene glycol for 7 days. Drought stress obviously enhanced osmolyte accumulation, lipid peroxidation, and antioxidant enzyme activities. Proteomic data revealed drought stress activated several pathways in pitaya, including carbohydrate and energy metabolism at two drought stress treatment time-points (6 h and 3 days). Other metabolic pathways, including those related to aspartate, glutamate, glutathione, and secondary metabolites, were induced more at 3 days than at 6 h, whereas photosynthesis and arginine metabolism were induced exclusively at 6 h. Overall, protein expression changes were consistent with the physiological responses, although there were some differences in the timing. The increases in soluble sugar contents mainly resulted from the degradation and transformation of insoluble carbohydrates. Differentially accumulated proteins in amino acid metabolism may be important for the conversion and accumulation of amino acids. GSH and AsA metabolism and secondary metabolism may play important roles in pitaya as enzymatic and nonenzymatic antioxidant systems. The enhanced carbohydrate and energy metabolism may provide the energy necessary for initiating the above metabolic pathways. The current study provided the first proteome profile of this species exposed to drought stress, and may clarify the mechanisms underlying the considerable tolerance of pitaya to drought stress.

A comprehensive analysis of transcriptomic data for comparison of plants with different photosynthetic pathways in response to drought stress

“…Under drought conditions, the breakdown of starch in the chloroplast results in an increase in the levels of soluble sugars such as sucrose, glucose, and fructose [ 47 ]. Starch degradation is enhanced by increasing the expression of some key genes, including ISA3 , AMY3 , and BAM9 [ 48 ]. The up-regulation of genes involved in the starch degradation pathway might help in allocating sugar energy during drought stress by promoting the conversion of starch into glucose [ 46 ].…”

Drought Stress Alters Photosynthetic and Carbohydrate-related Proteins in Leaves of Banana

“…For example, using the tandem mass tags (TMT)-label LCMS/MS technique, Xiao et al (2020) found that 123 proteins in cotton roots were differentially altered in response to drought stress. Other gel-free-based proteomics studies have also been reported in pitaya (Wang et al, 2021), banana (Amnan et al, 2021), and wheat (Yan et al 2021).…”

Potassium alleviates over‐reduction of the photosynthetic electron transport chain and helps to maintain photosynthetic function under salt‐stress

“…In the process of plant evolution, plants have evolved various strategies by which to adapt to salt stress: (1) increase in the water absorption capacity of plants by increasing osmotic regulatory substances such as soluble sugar and proline (Wang, Ma, et al, 2021); (2) removal of excessive ROS by activating the antioxidative enzyme system to reduce oxidative damage in cells (Zhang, Li, et al, 2020); and (3) combining exogenous salt stress signals with endogenous developmental cues (such as plant hormone signals) in vivo, to optimize the balance between growth and stress response (Yu et al, 2020). The photosynthetic system of plants also forms three lines of defense against excess light energy: (1) attenuation of interception and absorption of light energy; (2) protection of the photosystems by avoiding oxidative damage caused by ROS and promoting the dissipation of excess light energy; and (3) repair of PSII injury (PSII turnover) (Dong et al, 2016).…”