Parental drought priming enhances tolerance to low temperature in wheat (Triticum aestivum) offspring

Enhancing stress resilience in soybeans (Glycine max): assessing the efficacy of priming and cross-priming for mitigating water deficit and waterlogging effects

Priming enables plants to respond more promptly, minimise damage, and survive subsequent stress events. Here, we aimed to assess the efficacy of priming and cross-priming in mitigating the stress caused by waterlogging and/or dehydration in soybeans (Glycine max ). Soybean plants were cultivated in a greenhouse in plastic pots in which soil moisture was maintained at pot capacity through irrigation. The first stress was applied in plants at the vegetative stage for 5days and involved either dehydration or waterlogging, depending on the treatment. Subsequently, the plants were irrigated or drained and maintained at pot capacity until the second stress. For the second stress, the conditions were repeated in plants at the reproductive stage. We then evaluated the levels of hydrogen peroxide (H2 O2 ), lipid peroxidation, total soluble sugars (TSS), amino acids, proline, and starch, and the activity of antioxidant, fermentative, and aminotransferase enzymes. Under waterlogging and dehydration, priming and cross-priming significantly increased the activity of antioxidant enzymes and the levels of TSS, amino acids, and proline while reducing H2 O2 concentration and lipid peroxidation. Under waterlogging, priming suppressed fermentative activity and increased carbohydrate content. This demonstrates that soybean plants activate their defence systems more promptly when subjected to priming.

Polystyrene nanoplastics in soil impair drought priming-induced low temperature tolerance in wheat

Drought priming is known to enhance plant low temperature tolerance, whereas polystyrene nanoplastic contamination exerts detrimental effects on plant growth. This study investigates the less-explored influence of nanoplastic contamination on cold stress tolerance in drought-primed plants. We compared the photosynthetic carbon assimilation, carbohydrate metabolism, reactive oxygen species metabolism, and grain yield between the non-primed and drought-primed wheat grown in both nanoplastic-contaminated and healthy soils. Our results reveal that the beneficial effects of drought priming on photosynthetic carbon assimilation and the efficiency of the "water-water" cycle were compromised in the presence of nanoplastics (nPS). Additionally, nPS exposure disturbed carbohydrate metabolism, which impeded source-to-sink transport of sugar and resulted in reduced grain yield in drought-primed plants under low temperature conditions. These findings unveil the suppression of nPS on drought-primed low-temperature tolerance (DPLT) in wheat plants, suggesting an intricate interplay between the induction of stress tolerance and responses to nPS contamination. The study raises awareness about a potential challenge for future crop production.

Nitrogen enhances the effect of pre-drought priming against post-anthesis drought stress by regulating starch and protein formation in wheat

Drought stress is one of the most serious environmental stress factor constraining crop production across the globe. Among cereals, wheat grains are very sensitive to drought as a small degree of stress can affect the enzymatic system. This study aimed to investigate whether nitrogen and pre-anthesis drought priming could enhance the action of major regulatory enzymes involved in starch accumulation and protein synthesis in bread wheat (Triticum aestivum L.). For this purpose, cultivars YM-158 (medium gluten) and YM-22 (low gluten) were grown in rain-controlled conditions under two nitrogen levels, that is, N180 (N1) and N300 (N2). Drought priming was applied at the jointing stage and drought stress was applied 7 days after anthesis. Drought stress reduced starch content but enhanced protein content in grains. N2 and primed plants kept higher contents of nonstructural carbohydrates, fructans, and sucrose; with higher activity of sucrose-phosphate synthase in flag leaves. Furthermore, N2 and priming treatments showed higher sink ability to develop grains by showing higher sucrose-to-starch conversion activities of adenosine diphosphate-glucose pyrophosphorylase, uridine diphosphate glucose pyrophosphorylase, sucrose-synthase, soluble-starch synthase, starch branching enzyme, and granule-bound starch synthase as compared to N1 and non-primed treatments. The application of N2 and primed treatment showed a greater ability to maintain grain filling in both cultivars as compared to N1 and non-primed crops. Our study suggested that high nitrogen has the potential to enhance the effect of pre-drought priming to change source-sink relationships and grain yield of wheat under drought stress during the filling process.

Environmental Stimuli: A Major Challenge during Grain Filling in Cereals

Light, temperature, water, and fertilizer are arguably the most important environmental factors regulating crop growth and productivity. Environmental stimuli, including low light, extreme temperatures, and water stresses caused by climate change, affect crop growth and production and pose a growing threat to sustainable agriculture. Furthermore, soil salinity is another major environmental constraint affecting crop growth and threatening global food security. The grain filling stage is the final stage of growth and is also the most important stage in cereals, directly determining the grain weight and final yield. However, the grain filling process is extremely vulnerable to different environmental stimuli, especially for inferior spikelets. Given the importance of grain filling in cereals and the deterioration of environmental problems, understanding environmental stimuli and their effects on grain filling constitutes a major focus of crop research. In recent years, significant advances made in this field have led to a good description of the intricate mechanisms by which different environmental stimuli regulate grain filling, as well as approaches to adapt cereals to changing climate conditions and to give them better grain filling. In this review, the current environmental stimuli, their dose-response effect on grain filling, and the physiological and molecular mechanisms involved are discussed. Furthermore, what we can do to help cereal crops adapt to environmental stimuli is elaborated. Overall, we call for future research to delve deeper into the gene function-related research and the commercialization of gene-edited crops. Meanwhile, smart agriculture is the development trend of the future agriculture under environmental stimuli.