Silica nanoparticles promote wheat growth by mediating hormones and sugar metabolism.

BACKGROUND: Silica nanoparticles (SiNPs) have been demonstrated to have beneficial effects on plant growth and development, especially under biotic and abiotic stresses. However, the mechanisms of SiNPs-mediated plant growth strengthening are still unclear, especially under field condition. In this study, we evaluated the effect of SiNPs on the growth and sugar and hormone metabolisms of wheat in the field. RESULTS: SiNPs increased tillers and elongated internodes by 66.7% and 27.4%, respectively, resulting in a larger biomass. SiNPs can increase the net photosynthetic rate by increasing total chlorophyll contents. We speculated that SiNPs can regulate the growth of leaves and stems, partly by regulating the metabolisms of plant hormones and soluble sugar. Specifically, SiNPs can increase auxin (IAA) and fructose contents, which can promote wheat growth directly or indirectly. Furthermore, SiNPs increased the expression levels of key pathway genes related to soluble sugars (SPS, SUS, and α-glucosidase), chlorophyll (CHLH, CAO, and POR), IAA (TIR1), and abscisic acid (ABA) (PYR/PYL, PP2C, SnRK2, and ABF), whereas the expression levels of genes related to CTKs (IPT) was decreased after SiNPs treatment. CONCLUSIONS: This study shows that SiNPs can promote wheat growth and provides a theoretical foundation for the application of SiNPs in field conditions.

Identification and evolutionary analysis of the metal-tolerance protein family in eight Cucurbitaceae species.

Metal-tolerance proteins (MTPs) are divalent cation transporters and play fundamental roles in plant metal tolerance and ion homeostasis. Despite that, a systematic investigation of MTPs in Cucurbitacea is still lacking. In this study, 142 MTPs were identified from 11 released genomes of 8 Cucurbitaceae species. They were phylogenetically separated into three clusters (Zn-cation diffusion facilitator proteins [CDFs], Fe/Zn-CDFs, and Mn-CDFs) and further subdivided into seven groups (G1, G5, G6, G7, G8, G9, and G12). Characterization analysis revealed that most MTPs were plasma membrane-located hydrophobic proteins. Motif and exon/intron analysis showed that members in the same group contained similar conserved motifs and gene structures. Moreover, 98 pairs of segmental-like duplication events were found. The nonsynonymous/synonymous substitution ratios between each pair were less than 1, implying that Cucurbitaceae MTPs were under purification selection. Expression profiling suggested that several MTP genes, such as CsCLMTP1, CmeMTP3, LsMTP3, and Cl97103MTP3, were constitutively expressed in corresponding Cucurbitaceae species, and their expression levels were not significantly altered by NaCl, drought, or pathogen infection. The expression patterns of cucumber MTP genes under Zn2+ , Cu2+ , Mn2+ , and Cd2+ stress were studied by quantitative real-time polymerase chain reaction and the results showed that these MTPs were induced by at least one metal ion, suggesting their involvement in metal tolerance or transportation. The identification and comprehensive investigation of MTP family members will provide a basis for the analysis of ion transport functions and ion tolerance mechanisms of Cucurbitaceae MTPs.

Identification of Reference Genes for Reverse Transcription-Quantitative PCR Analysis of Ginger Under Abiotic Stress and for Postharvest Biology Studies.

Gene expression analysis largely improves our understanding of the molecular basis underpinning various plant biological processes. Stable reference genes play a foundational role during the normalization of gene expression levels. However, until now, there have been few reference genes suitable for ginger reverse transcription-quantitative PCR (RT-qPCR) research. In this study, 29 candidate reference genes with stable expression patterns across multiple ginger tissues and 13 commonly used reference genes were selected to design RT-qPCR primers. After amplification specificity validation, 32 candidates were selected and further evaluated by RT-qPCR using samples from various organs subjected to NaCl, drought, heat, waterlogging, and chilling stress. Four strategies, including delta-CT, BestKeeper, geNorm, and NormFinder, were used to rank the stability of reference genes, and the ranks produced by these four strategies were comprehensively evaluated by RefFinder to determine the final rank. Overall, the top three stability reference genes indicated by RefFinder were RBP > ATPase > 40S_S3. Their expression pattern correlation analysis showed that the coefficients among each pair of RBP, ATPase, and 40S_S3 were larger than 0.96, revealing consistent and stable expression patterns under various treatments. Then, the expression of three pathogenesis-related (PR) genes and seven MYB genes in rhizomes during postharvest storage and subjected to pathogen infection was normalized by RBP, ATPase, 40S_S3, RBP and ATPase, ATPase and 40S-S3, and RBP and 40S-S3. The results showed that PR and MYB genes were induced by postharvest deterioration and pathogen infection. The correlation coefficients of RBP/ATPase, RBP/40S_S3, ATPase/40S_S3, RBP and ATPase/ATPase and 40S-S3, RBP and ATPase/RBP and 40S-S3, and ATPase and 40S-S3/RBP and 40S-S3 were 0.99, 0.96, 0.99, 0.99, 1.00, and 1.00, respectively, which confirmed the stability of these three reference genes in postharvest biology studies of ginger. In summary, this study identified appropriate reference genes for RT-qPCR in ginger and facilitated gene expression studies under biotic and abiotic stress conditions.

Silicon Nanoparticles Enhance Ginger Rhizomes Tolerance to Postharvest Deterioration and Resistance to Fusarium solani.

Postharvest deterioration of ginger rhizome caused by microorganisms or wound infections causes significant economic losses. Fusarium solani is one of the important causal agents of prevalent ginger disease soft rot across the world. The massive and continuous use of chemical fungicides in postharvest preservation pose risks to human health and produce environmental contamination. Hence, new alternative tools are required to reduce postharvest deterioration and extend the postharvest life of ginger. In this study, the use of silicon nanoparticles (SiNPs) on the storability of ginger rhizomes during postharvest storage and their resistance to Fusarium solani was investigated. The results showed that 50, 100, and 150 mg L-1 of SiNPs increased the firmness of the ginger rhizome during storage but decreased the decay severity, water loss, total color difference, and the reactive oxygen species (ROS; H2O2 and superoxide anion) accumulation. Specifically, 100 mg L-1 (SiNP100) demonstrated the best effect in the extension of postharvest life and improved the quality of the ginger rhizomes. SiNP100 application increased the activities of antioxidant enzymes (SOD and CAT) and the total phenolics and flavonoid contents, thereby reducing the ROS accumulation and malondialdehyde (MDA) content. Meanwhile, SiNP100 treatment negatively impacts the peroxidase (POD) and polyphenol oxidase (PPO) activities, which may have contributed to the lower level of lignin and decreased total color difference. SiNP100 likely decreased water loss and the transfer of water by altering the expression of aquaporin genes. Moreover, SiNP100 modulated the expression of lignin synthesis and phytopathogenic responses genes including MYB and LysM genes. Furthermore, SiNP100 inhibited Fusarium solani by preventing the penetration of hyphae into cells, thus decreasing the severity of postharvest pathogenic decay. In summary, this study revealed the physiology and molecular mechanisms of SiNPs-induced tolerance to postharvest deterioration and resistance to disease, which provides a foundation for using SiNPs resources as a promising alternative tool to maintain ginger quality and control postharvest diseases.