Carbon-based nanomaterials (CBNs) are often used for potential agricultural applications. Since CBNs applied to plants can easily enter plant organs and reach the human diet, the consequences of the introduction of CBNs into the food chain need to be investigated. We created a platform for a comprehensive investigation of the possible health risks of multiwalled carbon nanotubes (CNTs) accumulated in the organs of exposed tomato plants. Quantification and visualization of CNTs absorbed by plant organs were determined by microwave-induced heating (MIH) and radio frequency (RF) heating methods. Feeding mice with CNT-contaminated tomatoes showed an absence of toxicity for all assessed animal organs. The amount of CNTs accumulated inside the organs of mice fed with CNT-containing fruits was assessed by an RF heating technique and was found to be negligible. Our work provides the experimental evidence that the amount of CNTs accumulated in plant organs as a result of nanofertilization is not sufficient to induce toxicity in mice.

ERECTA gene family encodes leucine-rich repeat receptor-like kinases that control major aspects of plant development such as elongation of aboveground organs, leaf initiation, development of flowers, and epidermis differentiation. To clarify the importance of ERECTA signaling for the development of soybean (Glycine max), we expressed the dominant-negative ERECTA gene from Arabidopsis thaliana that is truncated in the kinase domain (AtΔKinase). Expression of AtΔKinase in soybean resulted in the short stature, reduced number of leaves, reduced leaf surface area and enhanced branching in the transgenic plants. The transgenic AtΔKinase soybean plants exhibited increased tolerance to water deficit stress due to the reduction of total leaf area and reduced transpiration compared to the wild-type plants. Production of seeds in AtΔKinase lines was higher compared to wild type at regular conditions of cultivation and after exposure to drought stress. Transgenic seedlings expressing AtΔKinase were also able to withstand salt stress better than the wild-type. Established results demonstrated the significance of native soybean genes (GmER and GmERL) in development and stress response of soybean, and suggested that the truncated ERECTA gene of Arabidopsis thaliana can be used to manipulate the growth and stress response of different crop species.

Carbon-based nanomaterials (CBNs) such as carbon nanotubes (CNTs) and graphene can be beneficial to crops exposed to abiotic stresses such as drought and high salinity. Our findings suggest that the improvement observed in stressed crops treated with CBNs can be associated with CBN-induced restoration of gene expression. When subjected to salt stress, sorghum seedlings showed modified expression in 51 stressrelated genes. The introduction of CNTs or graphene into the salty growth medium resulted in the restoration of the expression of 29 affected genes, resembling that of untreated sorghum seedlings. RNA-Seq approach allowed us to analyze the total gene expression of CBN-treated rice exposed to water-deficit stress and gene expression of CBN-treated tomato plants exposed to salt stress. The application of CNTs or graphene resulted in full or partial restoration of expression of 458 and 1620 genes, respectively, affected by water-deficit stress in rice. Similarly, CBN treatment of NaCl-exposed tomato seedlings led to full or partial restoration of 1639 and 1391 salt-affected transcripts, respectively. Of the genes with restored expression, many of them were identified as major stress-response genes and major transcriptional factors (aquaporins, dehydrins, and heat shock proteins/co-chaperons, NAC, WRKY) and were associated with key stress-signaling pathways (ABA-signaling, InsP 3 signaling, and MAPK signaling) in all three tested plant species. These findings provide evidence that CBNs can provide halotolerance and drought tolerance by normalizing the expression of affected stress genes.

Application of carbonaceous nanomaterials (CNMs) to the soil-plant system can affect plant physiology, with positive results ranging from enhanced seed germination and root system development to improved stress tolerance. The...

Improvement of drought tolerance of crops is a great challenge in conditions of increasing climate change. This report describes that the silencing of the synaptotagmin-5 (OsSYT-5) gene encoding the rice Ca2+ sensing protein with a C2 domain led to a significant improvement of rice tolerance to water deficit stress. Transgenic lines with suppressed expression of the OsSYT-5 gene exhibited an enhanced photosynthetic rate but reduced stomatal conductance and transpiration during water deficit stress. The abscisic acid (ABA) content under both normal and drought conditions was elevated in the leaves of the transgenic rice as compared to the wild type. The silencing of the OsSYT-5 gene affected the expression of several genes associated with ABA-related stress signaling in the transgenic rice plants. In the water deficit experiment, the transgenic lines with a silenced OsSYT-5 gene exhibited symptoms of drought stress seven days later than the wild type. Transgenic lines with suppressed OsSYT-5 gene expression exhibited higher pollen viability and produced more grains compared to the wild type at both normal and drought stress conditions.