A cascade formed by phosphorylation events of mitogen‐activated protein kinases (MAPKs) takes part in plant stress responses. However, the roles of these MAPKs in resistance of potato (Solanum tuberosum) against Phytophthora pathogens is not well studied. Our previous work showed that a Phytophthora infestans RXLR effector targets and stabilizes the negative regulator of MAPK kinase 1 of potato (StMKK1). Because in Arabidopsis thaliana the AtMPK4 is the downstream phosphorylation target of AtMKK1, we performed a phylogenetic analysis and found that potato StMPK4/6/7 are closely related and are orthologs of AtMPK4/5/11/12. Overexpression of StMPK4/7 enhances plant resistance to P. infestans and P. parasitica. Yeast two‐hybrid analysis revealed that StMPK7 interacts with StMKK1, and StMPK7 is phosphorylated on flg22 treatment and by expressing constitutively active StMKK1 (CA‐StMKK1), indicating that StMPK7 is a direct downstream signalling partner of StMKK1. Overexpression of StMPK7 in potato enhances potato resistance to P. infestans. Constitutively active StMPK7 (CA‐StMPK7; StMPK7^{D198G, E202A}) was found to promote immunity to Phytophthora pathogens and to trigger host cell death when overexpressed in Nicotiana benthamiana leaves. Cell death triggered by CA‐StMPK7 is SGT1/RAR1‐dependent. Furthermore, cell death triggered by CA‐StMPK7 is suppressed on coexpression with the salicylate hydroxylase NahG, and StMPK7 activation promotes salicylic acid (SA)‐responsive gene expression. We conclude that potato StMPK7 is a downstream signalling component of the phosphorelay cascade involving StMKK1 and StMPK7 plays a role in immunity to Phytophthora pathogens via an SA‐dependent signalling pathway.

Summary: Phytophthora infestans causes severe losses in potato production. The MAPK kinase StMKK1 was previously found to negatively regulate potato immunity to P. infestans. Our results showed that StMKK1 interacts with a protein tyrosine phosphatase, referred to as StPTP1a, and StMKK1 directly phosphorylates StPTP1a at residues Ser‐99, Tyr‐223 and Thr‐290. StPTP1a is a functional phosphatase and the phosphorylation of StPTP1a at these three residues enhances its stability and catalytic activity. StPTP1a negatively regulates potato immunity and represses SA‐related gene expression. Furthermore, StPTP1a interacts with, and dephosphorylates, the StMKK1 downstream signalling targets StMPK4 and −7 at their Tyr‐203 residue resulting in the repression of salicylic acid (SA)‐related immunity. Silencing of NbPTP1a + NbMPK4 or NbPTP1a + NbMPK7 abolished the plant immunity to P. infestans caused by NbPTP1a silencing, indicating that PTP1a functions upstream of NbMPK4 and NbMPK7. StMKK1 requires StPTP1a to negatively regulate SA‐related immunity and StPTP1a is phosphorylated and stabilized during immune activation to promote the de‐phosphorylation of StMPK4 and −7. Our results reveal that potato StMKK1 activates and stabilizes the tyrosine phosphatase StPTP1a that in its turn de‐phosphorylates StMPK4 and −7, thereby repressing plant SA‐related immunity.

Soybean ( Glycine max L.) one of the world’s most important crops that is prized for its high protein and lipid content. As a prominent member of the carbon nanomaterial family, graphene oxide (GO) exhibits remarkable fertilizer adsorption and slow-release capabilities owing to its high specific surface area and abundant oxygen-containing functional groups, demonstrating broad application prospects in agricultural production. However, its potential role in regulating soybean growth and modulating the rhizosphere microbiome remains poorly understood. To elucidate the mechanism by which GO modulates soybean growth, we investigated eight cultivars (SN24, CD5, 7534, 15GI-16, ZH75, G135, L2012-7, and CD13) with a 30 mg/L GO treatment. The results demonstrate that GO application significantly enhanced key agronomic traits, increasing plant height by 7.17–51.05%, stem diameter by 12.39–63.34%, and the number of root nodules by 33.33–328.57%, along with increase in root biomass. Rhizosphere microbiome analysis revealed that GO restructured microbial communities in L2012–7 and significantly increased bacterial and fungal abundance or diversity based on operational taxonomic unit (OTU) levels ( p < 0.05). Taxonomic profiling identified GO-enriched beneficial genera ( Sinorhizobium , Sphingomonas and Trichoderma ), with LEfSe and Random Forest analyses confirming that Sinorhizobium is a keystone taxon. Mechanistically, Sinorhizobium fredii ( Sf01 ) was successfully isolated and identified from soybean rhizosphere soil, which was shown to promote soybean growth. Treatment with 5, 30, and 50 mg/L GO promoted the colony growth of S. fredii ( Sf01 ) by 40.2%, 42.9%, and 55.5%, respectively, whereas 100 mg/L GO inhibited its growth compared to the control. Furthermore, soil nutrient analysis demonstrated that GO significantly enhanced the contents of soil organic matter, total nitrogen, available potassium, available phosphorus, ammonium nitrogen, and humic acid in soybean rhizosphere soil. Our experimental results demonstrate that GO reshapes the soybean rhizosphere microbial community, which in turn enriches keystone beneficial microbes S. fredii ( Sf01 ) and enhances soil fertility retention capacity. This cascade of effects collectively promotes soybean plant growth, offering a nano-enabled strategy to reduce reliance on synthetic fertilizers.

Poplar trees and saline–alkali soil commonly occur in northern China, especially around the Datong district in northern Shanxi. To better utilize this type of soil, it is important to know how to neutralize saline–alkali conditions and how poplar leaves decompose in this soil media. Graphene oxide (GO) is widely known for improving soil nutrient content in agricultural and forestry soils. Here, we examined the effect of a graphene oxide composite combined with the addition of external bacterial agents on the decomposition of poplar leaves in saline–alkali soil. A litterbag method was used, and content analyses were conducted on both the litter residue and the decomposed soil at different sampling times. Overall, the humus content of the leaf-litter–decomposed soil gradually increased over time. Meanwhile, the total nitrogen, phosphorus, ammonium nitrogen, available potassium, and most phosphorus contents showed a trend of initially decreasing slightly and then gradually increasing. Nutrient concentrations, as well as humus content in the soil, reached their maximum after 120 days with the addition of both 25.0 mg/L GO and microbial agents. We conclude that the combination of GO and microbial agents promotes soil enzyme activity and accelerates litter decomposition, with the highest enzyme activity observed when both 25.0 mg/L GO and bacterial agents were present in the saline–alkali soil.

Grape ( Vitis vinifera L.) is an economically important fruit crop worldwide, with berry size and quality determining yield and market value. Graphene oxide (GO), a carbon nanomaterial with high specific surface area and abundant oxygen-containing functional groups, exhibits excellent fertilizer adsorption, holding promise for agricultural applications. This study systematically evaluated the effects of exogenous GO application on growth, rhizosphere microecology, and berry quality in ‘Crimson Seedless’ grape. The results showed that, compared with the control, treatment with 25 mg/L GO significantly promoted the plant height, stem diameter, and biomass accumulation of grape seedlings, and enhanced photosynthetic capacity. Rhizosphere soil microbial diversity analysis revealed that GO treatment increased the abundance and diversity of both bacteria and fungi. Further species composition and Linear discriminant analysis Effect Size (LEfSe) analysis indicated that GO treatment significantly enriched potentially beneficial microorganisms in the grape rhizosphere, including Bacillus , Sphingomonas , RB41 , and Mortierella . Soil physicochemical property measurements demonstrated that, compared with the control, GO significantly increased the contents of soil organic matter, total nitrogen, ammonium nitrogen, available potassium, and humic acid by 26.29%, 65.57%, 26.02%, 181.79%, and 14.05%, respectively, while reducing total phosphorus, total potassium, and available phosphorus. Regarding fruit quality, GO significantly increased berry weight, firmness, shape index, and contents of total sugar, vitamin C, soluble solids, tannins, anthocyanins, calcium and 23 Amino acid in berries compared with both the control and Bayer fertilizers (BR, Bayer AG, Cat: Dabs-1L) treatment. Collectively, these findings elucidate GO-mediated growth promotion and fruit quality regulation in grape, providing a theoretical and practical basis for broader agricultural GO application.

China produces abundant corn stover annually, and direct incorporation into farmland offers a cost-effective route. However, this practice suffers from slow decomposition, poor seedling growth, high disease incidence, and limited carbon sequestration. In this study, we investigated the effects of graphene oxide (GO) on straw degradation by Trichoderma harzianum (BJ9) and the underlying mechanisms. Our results demonstrated that GO at concentrations of 5, 25, and 50 mg/L significantly promoted the mycelial growth of BJ9, with promotion rates of 32.04%, 40.74%, and 39.51%, respectively, whereas GO at 100 mg/L inhibited colony development. A litterbag assay showed that 25 mg/L GO significantly enhanced straw degradation, increasing mass loss after 60 days compared to BJ9 alone. Enzymatic assays revealed that GO elevated cellulase and lignin peroxidase activities of BJ9: at 5, 25, and 50 mg/L, cellulase increased by 20.71%, 59.02%, and 48.57%, and lignin peroxidase by 18.31%, 39.13%, and 31.6%, respectively. Soil analyses demonstrated that GO + BJ9 co-application raised soil organic matter, total nitrogen, ammonium nitrogen, available potassium, available phosphorus, and humic acid relative to BJ9 alone. RNA-seq further corroborated these results, showing upregulation of multiple glycoside hydrolase family genes, indicating that GO induces key lignocellulose degrading enzyme expression in BJ9. Consequently, GO-supplemented treatments improved corn stover degradation efficiency and shortened decomposition time compared with the strain control. Collectively, these findings highlight GO as a functional nanomaterial that enhances fungal lignocellulose degradation, providing a basis for developing nano-enabled inoculants to optimize straw incorporation and promote resource utilization.