Silicon Alleviate Hypoxia Stress by Improving Enzymatic and Non-enzymatic Antioxidants and Regulating Nutrient Uptake in Muscadine Grape (Muscadinia rotundifolia Michx.)

Abstract

Flooding induces low oxygen (hypoxia) stress to plants, and this scenario is mounting due to hurricanes followed by heavy rains, especially in subtropical regions. Hypoxia stress results in the reduction of green pigments, gas exchange (stomatal conductance and internal CO2 concentration), and photosynthetic activity in the plant leaves. In addition, hypoxia stress causes oxidative damage by accelerating lipid peroxidation due to the hyperproduction of reactive oxygen species (ROS) in leaf and root tissues. Furthermore, osmolyte accumulation and antioxidant activity increase, whereas micronutrient uptake decreases under hypoxia stress. Plant physiology and development get severely compromised by hypoxia stress. This investigation was, therefore, aimed at appraising the effects of regular silicon (Si) and Si nanoparticles (SiNPs) to mitigate hypoxia stress in muscadine (Muscadinia rotundifolia Michx.) plants. Our results demonstrated that hypoxia stress reduced muscadine plants’ growth by limiting the production of root and shoot dry biomass, whereas the root zone application of both Si and SiNP effectively mitigated oxidative and osmotic cell damage. Compared to Si, SiNP yielded better efficiency by improving the activity of enzymatic antioxidants [including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)], non-enzymatic antioxidants [ascorbic acid (AsA) and glutathione contents], and accumulation of organic osmolytes [proline and glycinebetaine (GB)]. SiNP also regulated the nutrient profile of the plants by increasing N, P, K, and Zn contents while limiting Mn and Fe concentration to a less toxic level. A negative correlation between antioxidant activities and lipid peroxidation rates was observed in SiNP-treated plants under hypoxia stress. Conclusively, SiNP-treated plants combat hypoxia more efficiently stress than conventional Si by boosting antioxidant activities, osmoprotectant accumulation, and micronutrient regulation.

Physiological and comparative transcriptome analysis of the response and adaptation mechanism of the photosynthetic function of mulberry (Morus alba L.) leaves to flooding stress

“… 79 Barickman et al 35 also found that the gas exchange parameters of the leaves decreased, and photosynthetic activity was damaged in cucumber under flooding stress. In a study by Zafar et al, 2 flooding stress also reduced the gas exchange parameters ( G s and C i ) and photosynthetic activity of muscadine grape ( Muscadinia rotundifolia Michx.) leaves.…”

“… 69 70 Similar to most abiotic stresses, flooding stress also reduces the photosynthetic capacity of plants, primarily in the reduction of photochemical activity and ability to assimilate carbon ability. 2 33 Chlorophyll fluorescence technology has become one of the most powerful and widely used techniques used to understand the photosynthetic processes and thus, serve as a reliable indicator of stress in plants. 71 Therefore, this study used this technique to analyze the effects of flooding stress on the activities of PSII and PSI in mulberry leaves.…”

“… 33 He et al 34 and Barickman et al 35 found that hypoxia limited the gas exchange parameters of plants and led to the impairment of photosynthetic activity. In a study by Zafa, 2 hypoxia stress reduced the photosynthetic pigments, stomatal conductance, intercellular CO 2 concentration and photosynthetic activity of plant leaves. The duration of flooding stress affected the damage of PSII structure and activity, as well as the development of plant photosynthetic regulation.…”

“…Under the influence of global climate change, extreme precipitation, increasing groundwater levels, unreasonable irrigation measures and other factors, flooding has become one of the major sources of adversity for plants, which seriously affects social security and environmental sustainability. 1 2 More than 1,700 M ha of land area throughout the world is seriously affected by soil flooding every year. 3 The high incidence of flooding causes more climate-related disasters to crops, agricultural assets and infrastructure than any other abiotic factor.…”

“…17 18 The primary challenge of flooding to plants is the energy crisis caused by the reduction of oxygen supply, 19 20 which damages the cell and physiological functions of plants and has a negative impact on their developmental stages. 2 Many studies have shown that mulberry can slow down surface runoff, protect soil resources, and show good adaptability to flooding. 21 22 After 90 days of soaking, the germination rate of mulberry seedlings could reach 62.6%.…”