Exogenous melatonin alleviates PEG-induced short-term water deficiency in maize by increasing hydraulic conductance

Abstract

Background: Water deficiency is likely to become more frequent and intense as a result of global climate change, which may severely impact agricultural production in the world. The positive effects of melatonin (MEL) on alleviation drought or osmotic stress-induced water deficiency in plants has been well reported. However, the underlying mechanism of MEL on the detailed process of plant water uptake and transport under water deficiency condition remains largely unknown. Results: Application of 1 μM MEL led to enhanced tolerance to water deficiency stress in maize seedlings, as evidenced by maintaining the higher photosynthetic parameters, leaf water status and plant transpiration rate. The relatively higher whole-plant hydraulic conductance (K plant) and root hydraulic conductance (Lp r) in MEL-treated seedlings suggest that exogenous MEL alleviated water deficiency stress by promoting root water absorption. HgCl 2 (aquaporin inhibitor) treatment inhibit the transpiration rate in MEL-treated plants greater than those of MELuntreated; after recovery by dithiothreitol (DTT, anti-inhibitor), the transpiration rate in MEL-treated plants increased much higher than those of untreated plants. Moreover, under water deficiency, the transcription level of aquaporin genes was up-regulated by MEL application, and the H 2 O 2 was less accumulated in MEL-treated root. Conclusions: Exogenous MEL promoted aquaporin activity, which contributed to the maintaining of Lp r and K plant under short-term water deficiency. The increased water uptake and transport lead to improved water status and thus increased tolerance to PEG-induced short-term water deficiency in maize seedlings.

Mechanistic insights on melatonin‐mediated drought stress mitigation in plants

“…Water deficit conditions in the soil may lead to the reduction of hydraulic conductivity in root cells depending upon the plant species (Martínez-Vilalta & Garcia-Forner, 2017). Melatonin can influence whole-plant hydraulic conductivity (K plant = K leaf + K stem + Lp r ) by promoting root water absorption and reducing transpiration rate under drought stress (Qiao et al, 2020). K plant , K leaf , K stem , and Lp r represent the whole-plant hydraulic conductance, leaf hydraulic conductance, stem hydraulic conductance, and root hydraulic conductance, respectively.…”

“…Under drought stress, the aquaporin activity is declined due to imbalance in Lp r and K plant (Qiao et al, 2020). Aquaporins are membrane intrinsic proteins, which facilitate the movement of water across the membrane in all living organisms (Kurowska et al, 2019).…”

“…Root hydraulic conductance (Lp r ) is mainly regulated by aquaporin activity, which is crucial for root water uptake (Javot & Maurel, 2002). Under drought stress, the aquaporin activity is declined due to imbalance in Lp r and K plant (Qiao et al, 2020). Aquaporins are membrane intrinsic proteins, which facilitate the movement of water across the membrane in all living organisms (Kurowska et al, 2019).…”

Ameliorative Effects of Calcium Sprays on Yield and Grain Nutritional Composition of Maize (Zea mays L.) Cultivars under Drought Stress

“…Drought or water deficiency is one of the most common abiotic stresses in agricultural production practically in arid and semi-arid environments. It is expected to be more frequent and intense as a result of global climate change, which may severely impact world crop production [7]. Drought is the most injurious stress that significantly influences the yield and quality traits of major cereal crops [8].…”

TIP Aquaporins in Plants: Role in Abiotic Stress Tolerance

“…The response of plants is very complicated and many mechanisms are initiated simultaneously to restore cellular homeostasis and promote survival [78]. Aquaporins are thought to be responsive to the stress signalling pathways and are also thought to be involved in the stress-coping mechanisms such as altering the tissue hydraulic conductivity [79,80]. Drought and salinity are two major factors that significantly limit plant growth and productivity [81,82].…”