Consistent aroma characteristics are important for tea products. However, understanding the formation of tea aroma flavor and correspondingly proposing applicable protocols to control tea quality and consistency remain major challenges. Oolong tea is one of the most popular teas with a distinct flavor. Generally, oolong tea is processed with the leaves of tea trees belonging to different subspecies and grown in significantly different regions. In this study, Yunnan and Fujian oolong teas, green tea, black tea, and Pu-erh tea were collected from major tea estates across China. Their sensory evaluation, main water-soluble and volatile compounds were identified and measured. The sensory evaluation, total polysaccharide, caffeine, and catechin content of Yunnan oolong tea was found to be different from that of Fujian oolong tea, a result suggesting that the kinds of tea leaves used in Yunnan and Fujian oolong teas were naturally different. However, according to their aroma compounds, principal component analysis (PCA) and cluster analysis (CA) of the volatile compounds showed that the two types of oolong teas were similar and cannot be clearly distinguished from each other; they are also different from green, black, and Pu-erh teas, a result indicating that the same oolong tea processing technology applied to different tea leaves results in consistent aroma characteristics. The PCA analysis results also indicated that benzylalcohol, indole, safranal, linalool oxides, β-ionone, and hexadecanoic acid methyl ester highly contributed to the distinct aroma of oolong tea compared with the other three types of teas. This study proved that the use of the same processing technology on two kinds of tea leaves resulted in a highly consistent tea aroma.

Modern instrumental analysis technology can provide various chemical data and information on tea samples. Unfortunately, it remains difficult to extract the useful information. We describe the use of chemical fingerprint similarities, combined with principal component and cluster analyses, to distinguish and recognize Pu-erh green teas, which from two tea mountains, Wuliang and Jingmai, in the Pu-erh district of Yunnan province. The volatile components of all 20 Pu-erh green teas (10 Wuliang and 10 Jingmai teas) were extracted and identified by headspace solid-phase micro extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). Sixty-three volatiles (including alcohols, hydrocarbons, ketones, and aldehydes) were identified in the 20 Pu-erh green teas, and differences in compound compositions between them were also observed. Through fingerprint similarity, combined with principal component and cluster analyses, the 20 Pu-erh green teas were differentiated successfully based on their volatile characteristics. This study demonstrates that the GC-MS combined with chemical fingerprint and unsupervised pattern recognition method is suitable for the investigation of the volatile profiling and evaluating the quality and authenticity of teas related to the different origins.

Microbial communities are not only an important indicator of soil status but also a determinant of plant nutrition and health levels. Loss of microbial community ecosystem control can directly lead to microbial disease occurrence. During the process of Yuanyang Nanqi wild imitation planting, root rot diseases frequently occur, seriously affecting their yield and quality. Via amplicon sequencing, this study mainly compared the microbial community composition between the rhizosphere soil and roots of healthy and diseased Yuanyang Nanqi with root rot. The α-diversity showed that the microbial community diversity and abundance in the roots of diseased Yuanyang Nanqi were much lower than those of those in healthy specimens, while no significant difference was found in the rhizosphere soil. The β-diversity showed that the bacterial community in the Gejiu region and the fungal community in the Honghe region were significantly different from those in other regions. The species relative abundance map showed that there was no obvious difference in microbial community composition between the rhizosphere soil and roots of healthy and diseased Nanqi, but in diseased specimens with root rot, the proportions of Pseudomonas and Fusarium increased. Based on a functional prediction analysis of FUNGuild, the results showed that the Nanqi roots were mainly pathological saprophytic type and that their rhizosphere soil was mainly saprophytic type. The microorganisms in the roots of Yuanyang Nanqi tubers with root rot were also isolated and identified through the use of the culture method. The possible pathogenic strains were tested via anti-inoculation, and Fusarium oxysporum was identified as one of the main pathogenic fungi of Nanqi root rot, which was consistent with the amplicon sequencing results. These results will help us understand the change trend of microbial communities in healthy and diseased plants and analyze the pathogens involved, the pathogenesis, and the beneficial microorganisms, which would provide a theoretical basis for effective biological control.

Aluminum (Al) toxicity in acidic soils severely inhibits root growth. While enhanced antioxidant defense and organic acid exudation are both known Al tolerance mechanisms, how these processes are coordinated remains unclear. This study investigates whether and how the soybean (Glycine max) superoxide dismutase gene GmSOD (GenBank accession no. M64267.1) orchestrates these responses via modulation of hydrogen peroxide (H₂O₂) signaling. Wild-type (WT) and GmSOD-overexpressing transgenic tobacco (Nicotiana benthamiana) lines ST7 were exposed to Al stress (0-400 μM). A combination of physiological assays, biochemical activity measurements, gene expression analysis (quantitative RT-PCR), protein-protein interaction studies (co-immunoprecipitation), and multivariate factor analysis was employed to dissect the response pathways. GmSOD overexpression conferred superior Al tolerance, as evidenced by better-maintained root growth in ST7 under moderate stress (≤200 μM). The transgenic line ST7 exhibited a stronger antioxidant system, resulting in lower H₂O₂ and malondialdehyde (MDA) accumulation. Crucially, under moderate Al stress, ST7 maintained root tips H₂O₂ within a narrow signaling range (0.35-0.6 μmol g^-1 FW). This specific H₂O₂ level promoted the phosphorylation of plasma membrane (PM) H⁺-ATPase (Gene: NtAHA2, GenBank Accession no: M80490) and enhanced its interaction with 14-3-3 proteins, leading to increased H⁺-pump activity and a significant boost in citrate exudation. In contrast, under severe stress (400 μM), H₂O₂ accumulated to toxic levels (>1.0 μmol g^-1 FW), inhibiting this pathway. Factor analysis distilled ten stress-response variables into two principal components-"Antioxidant Capacity" and "Al Toxicity Index"-quantitatively demonstrating that ST7 maintains a favorable balance at higher Al concentrations than WT. We propose a novel model in which GmSOD-mediated fine-tuning of H₂O₂ homeostasis plays a dual role: it directly alleviates oxidative damage and, at a specific low concentration, acts as a signal to activate the PM H⁺-ATPase-dependent citrate exudation pathway. This coupling of internal redox control with external detoxification constitutes a key integrative mechanism for Al tolerance, offering strategic insights for crop improvement.

Background: Fungal symbionts are critical for host plant survival but are vulnerable to abiotic stresses such as low temperature, which limits their agricultural utility. Armillaria mellea is an essential fungal partner for the cultivation of the valuable medicinal orchid Gastrodia elata (G. elata). Enhancing its cold tolerance is a key step toward stabilizing G. elata production. Methods: Based on G. elata transcriptome data, a manganese superoxide dismutase gene (GeSOD7) was identified and heterologously expressed in Escherichia coli for enzymatic characterization. The gene was then overexpressed in A. mellea via Agrobacterium tumefaciens-mediated transformation. Transgenic and wild-type strains were subjected to cold stress (13 °C for 45 days), after which physiological, biochemical, and molecular responses were analyzed. Results: Recombinant GeSOD7 showed optimal activity at pH 6.0 and 60 °C, with inhibition under high concentrations of metal ions, especially Mn2+ and Cu2+. Overexpression of GeSOD7 in A. mellea significantly improved hyphal growth and fresh weight under cold stress. Transgenic strains exhibited higher activities of catalase and glutathione peroxidase, increased accumulation of glutathione and proline, and reduced levels of hydrogen peroxide and malondialdehyde. Expression of genes involved in glutathione synthesis and peroxide detoxification was coordinately upregulated. Conclusions: This study demonstrates that heterologous expression of a plant-derived Mn-SOD can effectively enhance the cold stress tolerance of a symbiotic fungus by boosting its enzymatic and non-enzymatic antioxidant systems. These findings provide a novel genetic strategy for improving stress resilience in agriculturally important fungi and contribute to the sustainable cultivation of G. elata.