Omeprazole Promotes Chloride Exclusion and Induces Salt Tolerance in Greenhouse Basil

Abstract

The role of small bioactive molecules (<500 Da) in mechanisms improving resource use efficiency in plants under stress conditions draws increasing interest. One such molecule is omeprazole (OMP), a benzimidazole derivative and inhibitor of animal proton pumps shown to improve nitrate uptake and exclusion of toxic ions, especially of chloride from the cytosol of salt-stressed leaves. Currently, OMP was applied as substrate drench at two rates (0 or 10 μM) on hydroponic basil (Ocimum basilicum L. cv. Genovese) grown under decreasing NO3−:Cl− ratio (80:20, 60:40, 40:60, or 20:80). Chloride concentration and stomatal resistance increased while transpiration, net CO2 assimilation rate and beneficial ions (NO3−, PO43−, and SO42−) decreased with reduced NO3−:Cl− ratio under the 0 μM OMP treatment. The negative effects of chloride were not only mitigated by the 10 μM OMP application in all treatments, with the exception of 20:80 NO3−:Cl−, but plant growth at 80:20, 60:40, and 40:60 NO3−:Cl− ratios receiving OMP application showed maximum fresh yield (+13%, 24%, and 22%, respectively), shoot (+10%, 25%, and 21%, respectively) and root (+32%, 76%, and 75%, respectively) biomass compared to the corresponding untreated treatments. OMP was not directly involved in ion homeostasis and compartmentalization of vacuolar or apoplastic chloride. However, it was active in limiting chloride loading into the shoot, as manifested by the lower chloride concentration in the 80:20, 60:40, and 40:60 NO3−:Cl− treatments compared to the respective controls (−41%, −37%, and −24%), favoring instead that of nitrate and potassium while also boosting photosynthetic activity. Despite its unequivocally beneficial effect on plants, the large-scale application of OMP is currently limited by the molecule’s high cost. However, further studies are warranted to unravel the molecular mechanisms of OMP-induced reduction of chloride loading to shoot and improved salt tolerance.

Metabolic Insights into the Anion-Anion Antagonism in Sweet Basil: Effects of Different Nitrate/Chloride Ratios in the Nutrient Solution

“…This trend was significantly affected by the amount of chlorine. A reduction of the nitrate uptake in leaves was previously reported, also for other leafy greens [26,27]. In this work, while the chorine content in leaves well correlated with its increasing amount in the NS, a large nitrate reduction was present at the highest chlorine concentration.…”

Physiological Basis of Salt Stress Tolerance in a Landrace and a Commercial Variety of Sweet Pepper (Capsicum annuum L.)

“…Nevertheless, the mechanisms that control chloride accumulation and partitioning in plants have been scarcely addressed [ 9 ]. When chloride concentration reaches the toxicity threshold, chloroplast membrane stability and Rubisco efficiency are severely affected [ 31 , 32 , 33 ]. Consequently, chloride toxicity in plants induces leaf chlorosis and photosynthesis impairment, which in the most sensitive species causes severe growth and yield loss [ 31 , 33 ].…”

“…Consequently, chloride toxicity in plants induces leaf chlorosis and photosynthesis impairment, which in the most sensitive species causes severe growth and yield loss [ 31 , 33 ]. Several studies have identified chloride exclusion as an important adaptive mechanism for plants to cope with salt stress [ 32 , 33 , 34 ]. Our results show that the commercial cultivar had a higher chlorophyll content ( Figure 1 B), higher CO 2 assimilation rate ( Figure 2 ), higher F v /F m and lower F 0 compared to the landrace ( Figure 3 ).…”

Application of Trichoderma harzianum, 6-Pentyl-α-pyrone and Plant Biopolymer Formulations Modulate Plant Metabolism and Fruit Quality of Plum Tomatoes

“…Duncan’s multiple-range test was used to analyze separated means with a cut-off for statistical significance at p < 0.05. A principal component analysis was employed to investigate how the dominant quanti-qualitative parameters set clustered according to the treatments by using Minitab ® 18 statistical software (Minitab LLC, State College, PA, USA) [ 27 , 65 ]. The percentage increases were calculated as the difference between the treated sample values minus untreated sample values (increase), divided by the untreated sample values and multiplied by 100.…”