Molecular Mechanisms of Plant Defense against Abiotic Stress

The climatic changes and anthropogenic factors in recent decades (global warming, drought, salinity, extreme temperature, environmental pollution) have led to an increase in the negative impact of environmental factors on plants. Abiotic stress strongly influences the important processes of plants and thus affects their growth and development. The effects of stressors on the plants depend on the intensity, frequency, and duration of stress, plant species as well as a combination of various stressors. Plants have developed different mechanisms to limit adverse environmental conditions. In the publications in this Special Issue, Molecular Mechanisms of Plant Defense against Abiotic Stress, new information on plant defense mechanisms against abiotic and biotic stress is presented. The studies help us better understand plants' protection mechanisms again global climate change

Involvement of nanoparticles in mitigating plant's abiotic stress

Abiotic stress globally has imposed the sternest environmental issues which enforce a significant impact on agricultural food production. Particularly, salinity, drought, heavy metal, and extreme high and low temperature are the principal components of abiotic stresses. The majority of the agricultural land is altered by the stresses and impacted by the reduction of production. An environmental stress response is internally governed by intricate biochemical and molecular signal transduction events, that act in an orchestrated manner for determining the tolerance or sensitivity of the plants. With exposure to abiotic stress, plants respond by reprogramming the interconnected defense networks and metabolic pathways. The variety of agrarian, physiological practices and genetic engineering methods are adapted for promoting plant stress adaptability. With the advent of nanotechnology, its application in agriculture has emerged as a valuable tool to reach the goal of sustainable food production worldwide. Nanoparticles possess unique physicochemical properties which allow them to interact with biological systems in a specific manner in terms of size, large surface area, surface charge, etc. In this regard, numerous studies have been carried out to study the efficacious role of nanoparticles in strengthening plant stress resilience. In this review, we will discuss the molecular mechanisms governing the nanoparticle-mediated stress response to increase the potentiality of cultivated plants

Sensitivity of the Photosynthetic Apparatus in Maize and Sorghum under Different Drought Levels

Drought is one of the main environmental stress factors affecting plant growth and yield. The impact of different PEG concentrations on the photosynthetic performance of maize (Zea mays L. Mayflower) and sorghum (Sorghum bicolor L. Foehn) was investigated. The activity of the photosynthetic apparatus was assessed using chlorophyll fluorescence (PAM and JIP test) and photooxidation of P700. The data revealed that water deficiency decreased the photochemical quenching (qP), the ratio of photochemical to nonphotochemical processes (Fv/Fo), the effective quantum yield of the photochemical energy conversion in PSII (ΦPSII), the rate of the electron transport (ETR), and the performance indexes PItotal and PIABS, as the impact was stronger in sorghum than in maize and depended on drought level. The PSI photochemistry (P700 photooxidation) in sorghum was inhibited after the application of all studied drought levels, while in maize, it was registered only after treatment with higher PEG concentrations (30% and 40%). Enhanced regulated energy losses (ΦNPQ) and activation of the state transition under drought were also observed in maize, while in sorghum, an increase mainly in nonregulated energy losses (ΦNO). A decrease in pigment content and relative water content and an increase in membrane damage were also registered after PEG treatment. The experimental results showed better drought tolerance of maize than sorghum. This study provides new information about the role of regulated energy losses and state transition for the protection of the photosynthetic apparatus under drought and might be a practical approach to the determination of the drought tolerance of plants