Nanobiotechnology-mediated regulation of reactive oxygen species homeostasis under heat and drought stress in plants

Global warming causes heat and drought stress in plants, which affects crop production. In addition to osmotic stress and protein inactivation, reactive oxygen species (ROS) overaccumulation under heat and drought stress is a secondary stress that further impairs plant performance. Chloroplasts, mitochondria, peroxisomes, and apoplasts are the main ROS generation sites in heat- and drought-stressed plants. In this review, we summarize ROS generation and scavenging in heat- and drought-stressed plants and highlight the potential applications of plant nanobiotechnology for enhancing plant tolerance to these stresses

Licorice–wolfberry-derived nanomaterial improves the germination rate of wheat under salt stress by maintaining reactive oxygen species homeostasis

IntroductionThe research on improving the salt tolerance of crops through plant nanobiotechnology has been extensively reported. However, the mechanism by which plant - derived nanomaterials enhance the germination rate of wheat under salt stress remains elusive. Unveiling the mechanism by which plant - derived nanomaterials boost the salt tolerance of wheat is conducive to safeguarding food security.MethodsHerein, we used mesoporous self-assembly licorice and wolfberry-derived complex nanomaterial (LW-CNs) to soak wheat (Triticum aestivum L) seeds.ResultsThe size and zeta potential of LW-CNs were 42.2±8.2 nm and -19.6±1.5 eV, respectively. After 4 days of salt stress, LW-CNs-soaked wheat seeds presented a higher germination rate (78.4±8.3 vs 54.4±8.5%) and protein content (44.0±0.1 vs 39.1±0.2 mg g-1), but no significant effect was observed on fresh weight (2.6±0.4 vs 2.3±0.4 g). LW-CNs significantly increased the pigment content (chlorophyll a: 0.11±0.0 vs 0.03±0.0 mg g-1, chlorophyll b: 0.05±0.0 vs 0.02±0.0 mg g-1, and carotenoids: 10.3±0.0 vs 2.9±0.0 μg g-1). LW-CNs alleviated salt-induced reactive oxygen species (ROS) accumulated through increase superoxide dismutase (917.4±8.7 vs 767.5±1.6 U g-1), peroxidase (2458.7±5.0 vs 2070.5±14.8 U g-1), and catalase (158.3±3.9 vs 112.0±3.2 μmol min-1 g-1) activity. Soaking in LW-CNs maintained ROS homeostasis also through the ascorbic acid–glutathione cycle. Furthermore, LW-CNs elevated the K⁺/Na⁺ ratio within wheat seeds and augmented the activities of nitrogen metabolism enzymes.ConclusionOverall, our study demonstrates that soaking seeds with plant - derived nanomaterials promotes the growth and nutrient absorption of wheat under salt stress by modulating the homeostasis of reactive oxygen species (ROS) and the K⁺/Na⁺ ratio/

Planting Density and Sowing Date Strongly Influence Canopy Characteristics and Seed Yield of Soybean in Southern Xinjiang

Southern Xinjiang is an important soybean production region in China. However, the short growing season and the cultivation of winter crops (such as wheat) in the region limit the expansion of soybean planting areas. An increased planting density can compensate for the loss in yield due to delayed sowing. To identify the quantitative relationship between increased density and delayed days, a two-year field experiment was conducted at the Tarim University Agronomy Experiment Station. Two sowing dates (April 7 (S1) and May 7 (S2)) and three planting densities of 206,800 plants·ha−1 (D1), 308,600 plants·ha−1 (D2), and 510,200 plants·ha−1 (D3) were used to compare various plant growth parameters and canopy characteristics. Late sowing and a high planting density significantly increased the plant height (S2 was 37.3% higher than S1, and D3 was 17.6% and 8.8% higher than D1 and D2), main stem internode, petiole length, and the mean tilt angle of the leaves (S2 was 22.5% higher than S1, and D3 was 11.7% higher than D2) but reduced the stem diameter (D3 was 28.6% and 12.5% lower than D1 and D2), branch number (S2 was 26.7% lower than S1, and D2 was 75% lower than D1), canopy light transmittance (S2 was 49.2% lower than S1, and D3 was 36.7% and 20.8% lower than D1 and D2), photosynthetic rate, and dry matter. The highest yield was achieved at S1D1, but the lowest yield was found for S2D1. Overall, the results suggest that earlier sowing and a lower planting density contribute to achieving an optimum canopy structure and higher yield. Our conclusions provide a reference for soybean production in southern Xinjiang

Mn₃O₄ Nanoenzyme Seed Soaking Enhanced Salt Tolerance in Soybean Through Modulating Homeostasis of Reactive Oxygen Species and ATPase Activities

Soybean, an important cash crop, is often affected by soil salinity, which is one of the important types of abiotic stress that affects its growth. Poly (acrylic) acid coated Mn3O4 (PMO) has been reported to play a vital role in defending against a variety of abiotic stresses in plants. To date, the effects of PMOs on soybean have not been reported; this study explored the mechanism of PMO-enhanced soybean germination under salt stress. In this experiment, 100 mg/L PMO was used as an immersion agent with a salt treatment of 150 mM NaCl. The results showed that when compared with the PMO treatment, salt stress significantly decreased the germination rate, fresh weight, carbohydrate content, and antioxidant enzyme activity of soybean and significantly increased the contents of reactive oxygen species, malondialdehyde, and osmoregulatory substances. However, PMO treatment enhanced the antioxidant defense system and significantly reduced the malondialdehyde content of soybean. Moreover, the activities of H+-ATPase and Ca2+-ATPase were significantly higher in treated soybean than in the control, and the content of ATP was also higher in treated soybean than in the control. Generally, PMO regulates the homeostasis of reactive oxygen species and reduces ATP consumption, thereby improving the ability of soybeans to germinate under salt stress. This study provides new insights into how nanomaterials improve plant salt tolerance

Effects of Delayed Application of Nitrogen Fertilizer on Yield, Canopy Structure, and Microenvironment of Winter Wheat with Different Planting Densities

Nitrogen fertilizer setback and planting density both affect wheat yield. However, the differences in winter wheat yield and its components, canopy structure, and microenvironment caused by N fertilizer setback at different planting densities are not clear. A two-year field experiment was conducted to investigate the most suitable planting density and N fertilizer setback combinations for winter wheat. Three planting densities of 3.3, 2.36, and 1.77 million plants·hm−2, and two basal fertilizer/nodulation and fertilizer/spike fertilizer ratios of 6:4:0 and 4:3:3, respectively, were used in the experiment. The results of the two-year experiment showed that, under the same planting density, the yields of wheat with nitrogen fertilizer setback increased by 8.2%, 2.7%, and 2.8%, respectively; the total leaf area of the upper trifoliate leaves increased by 10.7–17.4%; and the leaf area index (LAI) increased by 5.4% and 5.3%, respectively. The results showed that the yield, the effective number of spikes, leaf area index, and vertical light interception of wheat at a density of 3.30 million plants·hm−2 were higher than those of the other treatments. In both years of the experiment, the planting density of 3.30 million plants·hm−2 with nitrogen fertilizer setback (basal fertilizer/nodulation fertilizer/spike fertilizer = 4:3:3) was the best. Therefore, a nitrogen application of 240 kg·hm−2 and a planting density of 3.30 million hm−2 with nitrogen fertilizer setback was found to be the best combination

Functional connectome prediction of anxiety related to the COVID-19 pandemic

Increased anxiety in response to the COVID-19 pandemic has been widely noted. The purpose of this study was to test whether the prepandemic functional connectome predicted individual anxiety induced by the pandemic. Anxiety scores from healthy undergraduate students were collected during the severe and remission periods of the pandemic (first survey, February 22-28, 2020, N=589; second survey, April 24 to May 1, 2020, N=486). Brain imaging data and baseline (daily) anxiety ratings were acquired before the pandemic. The predictive performance of the functional connectome on individual anxiety was examined using machine learning and was validated in two external undergraduate student samples (N=149 and N=474). The clinical relevance of the findings was further explored by applying the connectome-based neuromarkers of pandemic-related anxiety to distinguish between individuals with specific mental disorders and matched healthy control subjects (generalized anxiety disorder, N=43; major depression, N=536; schizophrenia, N=72). Anxiety scores increased from the prepandemic baseline to the severe stage of the pandemic and remained high in the remission stage. The prepandemic functional connectome predicted pandemic-related anxiety and generalized to the external sample but showed poor performance for predicting daily anxiety. The connectome-based neuromarkers of pandemic-related anxiety further distinguished between participants with generalized anxiety and healthy control subjects but were not useful for diagnostic classification in major depression and schizophrenia. These findings demonstrate the feasibility of using the functional connectome to predict individual anxiety induced by major stressful events (e.g., the current global health crisis), which advances our understanding of the neurobiological basis of anxiety susceptibility and may have implications for developing targeted psychological and clinical interventions that promote the reduction of stress and anxiety