Metal based nanoparticles trigger the differential expression of key regulatory genes which regulate iron and zinc homeostasis mechanism in finger millet

Genetic biofortification: advancing crop nutrition to tackle hidden hunger

Malnutrition, often termed "hidden hunger," represents a pervasive global issue carrying significant implications for health, development, and socioeconomic conditions. Addressing the challenge of inadequate essential nutrients, despite sufficient caloric intake, is crucial. Biofortification emerges as a promising solution by enhance the presence of vital nutrients like iron, zinc, iodine, and vitamin A in edible parts of different crop plants. Crop biofortification can be attained through either agronomic methods or genetic breeding techniques. Agronomic strategies for biofortification encompass the application of mineral fertilizers through foliar or soil methods, as well as leveraging microbe-mediated mechanisms to enhance nutrient uptake. On the other hand, genetic biofortification involves the strategic crossing of plants to achieve a desired combination of genes, promoting balanced nutrient uptake and bioavailability. Additionally, genetic biofortification encompasses innovative methods such as speed breeding, transgenic approaches, genome editing techniques, and integrated omics approaches. These diverse strategies collectively contribute to enhancing the nutritional profile of crops. This review highlights the above-said genetic biofortification strategies and it also covers the aspect of reduction in antinutritional components in food through genetic biofortification.

Uncovering the genomic regions underlying grain iron and zinc content using genome-wide association mapping in finger millet

Finger millet, being rich source of essential minerals like iron and zinc, is an ideal model to identify candidate genes contributing to high grain iron content (GIC) and zinc content (GZC) in plants. Hence, finger millet diversity panel comprised of 202 genotypes was evaluated in two geographical locations and found to have a wide variation for GIC and GZC. A genome-wide association study using 2977 single nucleotide polymorphism (SNP) markers identified reliable marker-trait associations (MTAs). The use of general linear model (GLM) and mixed linear model (MLM) approaches revealed 5 and 8 common MTAs linked to GIC and GZC, respectively, for both Almora and Pantnagar locations, with a high level of significance (P < 0.01). However, 12 significant MTAs were found to be linked with GIC for Pantnagar location alone. The MTAs were associated with specific genes that produce ferritin (Fer1), iron-regulated transporter-like protein (IRT2), and yellow stripe-like 2 proteins (YSL2). These genes are likely linked to GIC variation in finger millet. Additionally, the variation in GZC in finger millet was connected to genes that encode zinc transporters, namely ZIP1 protein (ZIP1) and ZTP29-like protein (ZTP29). Compared to low GIC and GZC genotypes, high GIC and GZC genotypes exhibited greater relative expression of these genes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03889-1.

Differences in the nutritional quality of improved finger millet genotypes in Ethiopia

Improved crop genotypes are constantly introduced. However, information on their nutritional quality is generally limited. The present study reports the proximate composition and the concentration and relative bioavailability of minerals of improved finger millets of different genotypes. Grains of finger millet genotypes (n = 15) grown in research station during 2019 and 2020 in Ethiopia, and replicated three times in a randomized complete block design, were analysed for proximate composition, mineral concentration (iron, zinc, calcium, selenium), and antinutritional factors (phytate, tannin and oxalate). Moreover, the antinutritional factors to mineral molar ratio method was used to estimate mineral bioavailability. The result shows a significant genotypic variation in protein, fat and fibre level, ranging from 10% to 14.6%, 1.0 to 3.8%, and 1.4 to 4.6%, respectively. Similarly, different finger millets genotypes had significantly different mineral concentrations ranging from 3762 ± 332 to 5893 ± 353 mg kg-1 for Ca, 19.9 ± 1.6 to 26.2 ± 2.7 mg kg-1 for Zn, 36.3 ± 4.6 to 52.9 ± 9.1 mg kg-1 for Fe and 36.6 ± 11 to 60.9 ± 22 µg kg-1 for Se. Phytate (308-360 µg g-1), tannin (0.15-0.51 mg g-1) and oxalate (1.26-4.41 mg g-1) concentrations were also influenced by genotype. Antinutritional factors to minerals molar ratio were also significantly different by genotypes but were below the threshold for low mineral bioavailability. Genotype significantly influenced mineral and antinutritional concentrations of finger millet grains. In addition, all finger millet genotypes possess good mineral bioavailability. Especially, the high Ca concentration in finger millet, compared to in other cereals, could play a vital role to combating Ca deficiency. The result suggests the different finger millet genotypes possess good nutrient content and may contribute to the nutrition security of the local people.

Plant growth promoting potential of urea doped calcium phosphate nanoparticles in finger millet (Eleusine coracana (L.) Gaertn.) under drought stress

Drought is a leading threat that impinges on plant growth and productivity. Nanotechnology is considered an adequate tool for resolving various environmental issues by offering avant-garde and pragmatic solutions. Using nutrients in the nano-scale including CaP-U NPs is a novel fertilization strategy for crops. The present study was conducted to develop and utilize environment-friendly urea nanoparticles (NPs) based nano-fertilizers as a crop nutrient. The high solubility of urea molecules was controlled by integrating them with a matrix of calcium phosphate nanoparticles (CaP NPs). CaP NPs contain high phosphorous and outstanding biocompatibility. Scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD) were used to characterize the fabricated NPs. FE-SEM determined no areas of phase separation in urea and calcium phosphate, indicating the successful formation of an encapsulated nanocomposite between the two nano matrices. TEM examination confirmed a fiber-like structure of CaP-U NPs with 15 to 50 nm diameter and 100 to 200 nm length. The synthesized CaP-U NPs and bulk urea (0.0, 0.1% and 0.5%) were applied by foliar sprays at an interval of 15 days on pre-sowed VL-379 variety of finger millet (Eleusine coracana (L.) Gaertn.), under irrigated and drought conditions. The application of the CaP-U NPs significantly enhanced different plant growth attributes such as shoot length (29.4 & 41%), root length (46.4 & 51%), shoot fresh (33.6 & 55.8%) and dry weight (63 & 59.1%), and root fresh (57 & 61%) and dry weight (78 & 80.7%), improved pigment system (chlorophyll) and activated plant defense enzymes such as proline (35.4%), superoxide dismutase (47.7%), guaiacol peroxidase (30.2%), ascorbate peroxidase (70%) under both irrigated and drought conditions. Superimposition of five treatment combinations on drought suggested that CaP-U NPs at 0.5 followed by 0.1% provided the highest growth indices and defense-related enzymes, which were significantly different. Overall, our findings suggested that synthesized CaP-U NPs treatment of finger millet seeds improved plant growth and enzymatic regulation, particularly more in drought conditions providing insight into the strategy for not only finger millet but probably for other commercial cereals crops which suffer from fluctuating environmental conditions.

Elevated CO2 exacerbates effects of TiO2 nanoparticles on rice (Oryza sativa L.) leaf transcriptome and soil bacteria

Elevated CO₂ affects the plant rhizosphere and can therefore affect the fate and toxicity of soil contaminants. However, little is known about how the effects of nanoparticles on plants and soil bacteria will change under future CO₂ levels. A free-air CO₂ enrichment system with two CO₂ levels (ambient, 390 μmol mol^-1; elevated, 590 μmol mol^-1) was used to investigate the responses of rice (Oryza sativa L.) and soil bacteria to titanium dioxide nanoparticles (nano-TiO₂, 0 and 200 mg kg^-1). Results showed that nano-TiO₂ alone did not significantly affect rice growth but affected soil bacteria involved in the carbon and sulfur cycles. Elevated CO₂ alone increased rice plant biomass and up-regulated genes related to ribosomes, but its combination with nano-TiO₂ down-regulated genes related to photosynthesis and photosynthetic antennae. Elevated CO₂ also exacerbated the disturbance by nano-TiO₂ to soil bacteria involved in carbon and nitrogen cycles, and consequently inhibited the rice growth. These findings provide a reference for the comprehensive evaluation for the risk of soil pollution.

Leaf rolling in bread wheat (Triticum aestivum L.) is controlled by the upregulation of a pair of closely linked/duplicate zinc finger homeodomain class transcription factors during moisture stress conditions

Zinc finger-homeodomain (ZF-HDs) class IV transcriptional factors (TFs) is a plant-specific transcription factor and play a key role in stress responses, plant growth, development, and hormonal signaling. In this study, two new leaf rolling TFs genes, namely TaZHD1 and TaZHD10, were identified in wheat using comparative genomic analysis of the target region that carried a major QTL for leaf rolling identified through multi-environment phenotyping and high throughput genotyping of a RIL population. Structural and functional annotation of the candidate ZHD genes with its closest rice orthologs reflects the species-specific evolution and, undoubtedly, validates the notions of remote-distance homology concept. Meanwhile, the morphological analysis resulted in contrasting difference for leaf rolling in extreme RILs between parental lines HD2012 and NI5439 at booting and heading stages. Transcriptome-wide expression profiling revealed that TaZHD10 transcripts showed significantly higher expression levels than TaZHD1 in all leaf tissues upon drought stress. The relative expression of these genes was further validated by qRT-PCR analysis, which also showed consistent results across the studied genotypes at the booting and anthesis stage. The contrasting modulation of these genes under drought conditions and the available evidenced for its epigenetic behavior that might involve the regulation of metabolic and gene regulatory networks. Prediction of miRNAs resulted in five Tae-miRs that could be associated with RNAi mediated control of TaZHD1 and TaZHD10 putatively involved in the metabolic pathway controlling rolled leaf phenotype. Gene interaction network analysis indicated that TaZHD1 and TaZHD10 showed pleiotropic effects and might also involve other functions in wheat in addition to leaf rolling. Overall, the results increase our understanding of TaZHD genes and provide valuable information as robust candidate genes for future functional genomics research aiming for the breeding of wheat varieties tolerant to leaf rolling.

Plants and rhizospheric environment: Affected by zinc oxide nanoparticles (ZnO NPs). A review

Nowadays, there are many critical concerns in the agricultural sector, including reduced productivity of plants due to various environmental factors. Hence, a continuous innovation of existing technologies is necessary. Among the available technologies for sustainable agriculture, nanotechnology is one of the more promising technologies and has a great scope for development in agriculture. Zinc oxide nanoparticles (ZnO NPs) have attracted much attention due to their good properties and can be put into agriculture as nano-fertilizers, nano-growth regulators and nano-pesticides, although much remains to be explored about their mechanisms. Here, we review the literature on the interaction of ZnO NPs with plants through (i) uptake and transport pathways of ZnO NPs in plants. (ii) The mechanisms involved in improving growth, development and resistance. (iii) their effects on the rhizospheric environment. (iv) The toxic effects and mechanisms in plants. Our major conclusions are as follows: (1) they can be absorbed by the plant through the roots and leaves, with subsequent transformation. (2) moderate application can promote plant growth and mitigate stress, while excessive application can produce toxic effects. (3) the effects of them on the rhizospheric environment cannot be ignored. This study may provide a reference for the safe and effective use of ZnO NPs in agricultural production.