Introduction: The air-curing process of cigar tobacco, as a key step in enhancing the quality of cigars, is often susceptible to contamination by mold spores, which severely constrains the quality of cigar tobacco.Methods: This study employed high-throughput Illumina sequencing technology and a continuous flow analysis system to analyze the differences between the microbial communities and physicochemical components of moldy and healthy cigar tobacco leaves. Furthermore, correlation analysis was performed to reveal the impact of mold on the quality of cigar tobacco.Results: The differences between the microbial flora and physicochemical compositions of moldy (MC) and healthy (HC) tobacco leaves were analyzed, revealing significant disparities between the two groups. Aspergillus spp. represented the dominant mold in MC, with nine out of twelve isolated molds showing higher quantities on MC than on HC. Mold contamination notably decreased the total nitrogen (TN), total phosphorus (TP), total alkaloids (TA), starch, protein, and flavor constituents while increasing the total fatty acid esters (TFAA), which was accompanied by a shift towards weakly acidic pH in the leaves. Fungal community analysis indicated a significant reduction in the fungal operational taxonomic unit (OUT) numbers and diversity indices in MC, contrasting with the bacterial trends. Aspergillus exhibited significantly higher relative abundance in MC, with LEfSe analysis pinpointing it as the primary driver of differentiation. Furthermore, significant negative correlations were observed between Aspergillus and TP, starch, TA, and protein, while a significant positive association was evident with TFAA. Network analysis underscored the pivotal role of Aspergillus as the species influencing disparities between HC and MC, with its abundance serving as a critical determinant during the air-curing process.Discussion: This study elucidated substantial quality distinctions between MC and HC during air-curing, with Aspergillus emerging as the key species contributing to leaf mold.

Wood vinegar, a by-product of charcoal biomass pyrolysis, has been used as a biofungicide in plant disease management because of its antimicrobial properties. However, the physiological and biochemical mechanisms through which wood vinegar alleviates biotic stress are poorly understood. In this study, pot experiments were conducted to investigate the resistance and regulation mechanism of wood vinegar prepared from different raw materials (ZM) and from a single raw material (SM) in controlling tomato (Solanum lycopersicum “Bonny Best”) Fusarium wilt at different concentrations (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The results showed that ZM and SM had significant control effects on tomato fusarium wilt under different concentrations in the same growth cycle. Under biotic stress, the two kinds of wood vinegar significantly increased the plant height, stem diameter, leaf area and yield of tomato under the concentration of 0.3%, 0.6%, 0.9% and 1.2%, and significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in tomato leaves. The effect of 0.9% treatment was the most significant, ZM and SM significantly increased tomato yield by 122% and 74%, respectively, compared with CK under 0.9% treatment. However, the plant height, stem diameter and leaf area of tomato were significantly reduced under 1.5% treatment, but the content of soluble sugar, soluble protein and vitamin C in tomato fruit was the best. Compared with CK, ZM significantly increased by 14%, 193% and 67%, respectively, and SM significantly increased by 28%, 300% and 159%, respectively. Except for 0.3% treatment, both significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in tomato leaves. The response intensity of two kinds of wood vinegar—physiological and biochemical—to tomato disease resistance, growth and development, showed ZM > SM. The disease index of tomato showed highly significant negative correlation with plant height, stem thickness, leaf area and antioxidant physiology CAT, and highly significant positive correlation with MDA and H₂O₂ content. In conclusion, ZM was more effective than SM in enhancing tomato disease resistance by promoting tomato growth and development, decreasing leaf MDA and H₂O₂ content, and inducing antioxidant enzyme activity in leaves at moderate concentrations.

Dissolved organic matter (DOM) strongly influences the geochemical mobility of metal ions, yet little is known about the mechanism of lead (Pb) binding to DOM in the presence of copper (Cu) and zinc (Zn). This research used different types of ultraviolet–visible (UV–vis) spectroscopy analysis technologies, including differential log-transformed spectra coupled with spectral slope calculation, and two-dimensional correlation spectroscopy (2D-COS) analysis to investigate the binding characteristics between Pb and DOM in the presence of Zn and Cu, respectively. The results indicate that the addition both of Zn ²⁺or Cu ²⁺can reduce the binding of DOM to Pb ²⁺, with the effect of Cu ²⁺being the most obvious. Specifically, significant changes were evident in the differential log-transformed absorbance at higher Zn²⁺/Cu²⁺ concentrations, including modified spectral shapes, absorption wavelength fluctuation, and differential absorption intensity changes. The differential log-transformed absorbance spectral slopes (∆S_350-400) exhibited a positive correlation with the predicted NICA-Donnan model value in a wavelength range of 350–400 nm. This suggested that ∆S_350-400 served as an indicator for assessing the complexation characteristics of Pb and DOM binding in the presence of Zn²⁺ and Cu²⁺, respectively. The 2D-COS spectral results showed that the presence of Zn²⁺/Cu²⁺ changed the binding order of the DOM functional groups in response to Pb²⁺. This study revealed that Zn²⁺ and Cu²⁺ competed with Pb²⁺ for complex sites on the DOM surface in different ways, altering the ability of Pb²⁺ to bind with DOM. The results suggest that using differential log-transformed spectroscopy combined with ∆S_350-400 and 2D-COS analyses is a promising approach to understanding the mechanisms of Zn²⁺/Cu²⁺ effects on Pb-DOM interactions, which may provide new insights into the prevention, control, and remediation of environmental Pb pollution.

Quinoa (Chenopodium quinoa) is an Andean allotetraploid pseudocereal crop with higher protein content and balanced amino acid composition in the seeds. Ammonium (NH₄⁺), a direct source of organic nitrogen assimilation, mainly transported by specific transmembrane ammonium transporters (AMTs), plays important roles in the development, yield, and quality of crops. Many AMTs and their functions have been identified in major crops; however, no systematic analyses of AMTs and their regulatory networks, which is important to increase the yield and protein accumulation in the seeds of quinoa, have been performed to date. In this study, the CqAMTs were identified, followed by the quantification of the gene expression, while the regulatory networks were predicted based on weighted gene co-expression network analysis (WGCNA), with the putative transcriptional factors (TFs) having binding sites on the promoters of CqAMTs, nitrate transporters (CqNRTs), and glutamine-synthases (CqGSs), as well as the putative TF expression being correlated with the phenotypes and activities of GSs, glutamate synthase (GOGAT), nitrite reductase (NiR), and nitrate reductase (NR) of quinoa roots. The results showed a total of 12 members of the CqAMT family with varying expressions in different organs and in the same organs at different developmental stages. Complementation expression analyses in the triple mep1/2/3 mutant of yeast showed that except for CqAMT2.2b, 11/12 CqAMTs restored the uptake of NH₄⁺ in the host yeast. CqAMT1.2a was found to mainly locate on the cell membrane, while TFs (e.g., CqNLPs, CqG2Ls, B3 TFs, CqbHLHs, CqZFs, CqMYBs, CqNF-YA/YB/YC, CqNACs, and CqWRKY) were predicted to be predominantly involved in the regulation, transportation, and assimilation of nitrogen. These results provide the functions of CqAMTs and their possible regulatory networks, which will lead to improved nitrogen use efficiency (NUE) in quinoa as well as other major crops.