Severe water stress conditions limit growth and development of floricultural crops which affects flower quality. Hence, development of effective approaches for drought tolerance is crucial to limit recurring water deficit challenges. Foliar application of various plant growth regulators has been evaluated to improve drought tolerance in different floricultural crops; however, reports regarding the role of chitosan (Ci) on seasonal flowers like calendula are still scant. Therefore, we evaluated the role of Ci foliar application on morphological, physiological, biochemical, and anatomical parameters of calendula under water stress conditions. Different doses of Ci (0, 2.5, 5, 7.5, 10 mg L⁻¹) were applied through foliar application to evaluate their impact in enhancing growth and photosynthetic pigments of calendula. The optimized Ci level of 7.5 mg L⁻¹ was further evaluated to study mechanisms of water stress tolerance in calendula. Ci application significantly increased biomass and pigments in calendula. Ci (7.5 mg L⁻¹) resulted in increased photosynthetic rate (72.98%), transpiration rate (62.11%), stomatal conductance (59.54%), sub-stomatal conductance (20.62%), and water use efficiency (84.93%). Furthermore, it improved catalase, guaiacol peroxidase, and superoxide dismutase by 56.70%, 64.94%, and 32.41%, respectively. These results highlighted the significance of Ci in inducing drought tolerance in pot marigold.

The persistent nature of lead (Pb) and cadmium (Cd) in the environment severely affects plant growth and yield. Conversely, plants acquire zinc (Zn) from the soil for their vital physiological and biochemical functions. However, the interplay and coordination between essential and toxic metals for their uptake and translocation and the putative underlying epigenetic mechanisms have not yet been investigated in maize. Here, we report that the presence of Zn facilitates the accumulation and transport of Pb and Cd in the aerial parts of the maize plants. Moreover, the Zn, Pb, and Cd interplay specifically interferes with the uptake and translocation of other divalent metals, such as calcium and magnesium. Zn, Pb, and Cd, individually and in combinations, differentially regulate the expression of DNA methyltransferases, thus alter the DNA methylation levels at the promoter of Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) genes to regulate their expression. Furthermore, the expression of histone deacetylases (HDACs) varies greatly in response to individual and combined metals, and HDACs expression showed a negative correlation with ZIP transporters. Our study highlights the implication of DNA methylation and histone acetylation in regulating the metal stress tolerance dynamics through Zn transporters and warns against the excessive use of Zn fertilizers in metal contaminated soils.

Wheat (Triticum aestivum L.) is an essential food crop in terms of consumption as well as production. Aflatoxin exposure has a widespread public health impact in economically developing nations, so there is a need to establish preventive techniques for these high-risk populations. Pre-harvest and post-harvest practices are the two strategies used to control aflatoxin contamination, which include the use of genetically modified crops that show resistance against Aspergillus infection, the use of pesticides, changing the planting and harvesting time of crops, and physical, chemical, and biological methods. In this research, aflatoxin detection and quantification were performed in different wheat varieties to determine quantitative differences in comparison to the European Commission’s limit of 4 ppb aflatoxins in wheat. TLC for qualitative and the ELISA kit method for quantitative analysis of aflatoxins were used. Out of 56 samples, 35 were found contaminated with aflatoxins, while the remaining 21 samples did not show any presence of aflatoxins. Out of the 35 contaminated samples, 20 samples showed aflatoxin contamination within the permissible limit, while the remaining 15 samples showed aflatoxin concentration beyond the permissible level, ranging from 0.49 to 20.56 ppb. After quantification, the nine highly contaminated wheat samples were detoxified using physical, chemical, and biological methods. The efficiency of these methods was assessed, and they showed a significant reduction in aflatoxins of 53–72%, 79–88%, and 80–88%, respectively. In conclusion, the difference in aflatoxin concentration in different wheat varieties could be due to genetic variations. Furthermore, biological treatment could be the method of choice for detoxification of aflatoxins in wheat as it greatly reduced the aflatoxin concentration with no harmful effect on the quality of the grains.

The medicinal herb Geranium wallichianum belongs to the family Geraniaceae. The East Asian Himalayas are its primary habitat. Overexploitation and overharvesting pose a threat to this plant, given its extensive ethnomedical utilization in the community. In Pakistan, its population has already declined by over 75%. Given its critical medicinal importance, urgent conservation efforts are needed to prevent extinction. The aim of the current research was to determine the effectiveness of sucrose and polyethylene glycol (PEG) in decelerating the growth of this medicinally important species. Nodal segments were utilized as explant with varying levels of polyethylene glycol (PEG) (0.5% and 1.5%) and sucrose (4% and 8%) as treatments on different growth attributes. Over a 45-day period, PEG treatments (0.5% and 1.5%) proved more efficient compared to sucrose in suppressing in vitro growth, with reduced shoot lengths (0.92 and 0.57 cm), dry weight (0.04 and 0.02 g), and fresh weight (0.06 and 0.04 g). PEG also significantly enhanced phenolic levels (0.96 and 0.19 mg/g) and soluble sugars (4.07 and 4.12 mg/g) while reducing total protein level (2.38 and 2.32 mg/g) and total chlorophyll content (0.17 and 0.14 mg/g). The Pearson correlation analysis showed a negative association between phenolic levels and total chlorophyll content, chlorophyll a, and chlorophyll b. The length of the shoot had a negative relationship with phenolic level but a positive relationship with both fresh and dry weight. The principal component analysis revealed that total sugars and phenolics that were grouped separately from other variables led to stronger responses to osmotic stress. These outcomes suggested that higher PEG was successful in reducing in vitro growth throughout short-term preservation in comparison to sucrose. The outcomes of this research could be applied for the in vitro conservation of medical plants in the future.