Elucidating the endophytic bacterial and fungal community composition and diversity in the tree fern Alsophila spinulosa through meta-amplicon sequencing.

Plant tissues harbor abundant endophytes, which are crucial for plant growth. Endophytes present in Alsophila spinulosa, which is enriched with medicinal components, have not been isolated and characterized yet. Here we employed meta-amplicon sequencing to identify endophytic species and examined their diversity in the leaves, petioles, roots and stems of A. spinulosa. Our findings revealed 1,247 operational taxonomic units (OTUs) for endophytic bacteria across 210 species and 476 OTUs for endophytic fungi across 222 species. Alpha diversity analysis showed the highest endophytic bacterial diversity in A. spinulosa roots, whereas fungal diversity was similar across the leaf, petiole and root tissues. Fungal diversity in the leaves and petioles was markedly higher than that in the stems. Furthermore, beta diversity analysis revealed similarities in the endophytic bacterial and fungal compositions between the leaves and petioles, whereas the compositions in roots and stems considerably differed from those in the leaves and petioles. At the genus level, the predominant endophytic bacteria were Methylobacterium-Methylorubrum and Pseudomonas, whereas the predominant endophytic fungi were Cutaneotrichosporon and Pseudofabraea. Linear discriminant analysis effect size revealed characteristic endophytic bacterial genera specific to each tissue type and characteristic endophytic fungal genera specifically in the leaves, petioles and roots. The co-occurrence network analysis indicated that the complexity of endophyte networks was the highest in the leaves and the lowest in the stems of A. spinulosa. Overall, this study elucidates the distribution patterns of endophytes in A. spinulosa across various tissues, offering valuable microbial resources for the development of natural products for medicinal application.

Structural Characterization and Immunoenhancing Properties of Polysaccharide CPTM-P1 from Taxus media.

Polysaccharides extracted from Taxus media hrough an aqueous method were further refined by removing proteins via the Sevag technique and purified by dialysis. The separation of these polysaccharides was accomplished using a DEAE-cellulose chromatog-raphy column, yielding two distinct fractions, named CPTM-P1 and CPTM-P2. Notably, CPTM-P1 emerged as the primary polysaccharide component within Taxus media. Consequently, a comprehensive analysis focusing exclusively on CPTM-P1 was undertaken. The molecular weight of CPTM-P1 was established through gel permeation chromatography (GPC), and its monosaccharide composition was deciphered using HPLC-MS. The structure was further elucidated through nuclear magnetic resonance (NMR) spectroscopy. The molecular weight of CPTM-P1 was determined to be 968.7 kDa. The monosaccharide composition consisted of galactose (Gal), arabinose (Ara), galacturonic acid (Gal-UA), glucose (Glc), rhamnose (Rha), xylose (Xyl), mannose (Man), fucose (Fuc), glucuronic acid (Glc-UA), and ribose (Rib). The proportional distribution of these components was 30.53%, 22.00%, 5.63%, 11.67%, 11.93%, 1.69%, 8.50%, 1.23%, 5.63%, and 1.17%, respectively. This confirmed CPTM-P1 as an acidic heteropolysaccharide with a glycuronic acid backbone. Moreover, CPTM-P1 showed immunoenhancing properties, effectively augmenting the secretion of nitric oxide and cytokines (TNF-α, IL-1ß, and IL-6). Additionally, it significantly enhances the phagocytic capacity of RAW264.7 cells. These findings underscore the potential application of these polysaccharides in functional foods and pharmaceuticals, providing a solid scientific basis for further exploration and utilization of Taxus media polysaccharides.

Effects of Chinese fir planting and phosphorus addition on soil microbial biomass and extracellular enzyme activities.

Plants can alter soil microbial biomass and extracellular enzyme activities related with carbon (C), nitrogen (N), and phosphorus (P), through litter and root exudates, with consequences on soil carbon, nitrogen and phosphorus (P) cycling. However, it is not well known how the changes in soil phosphorus availability affect the relationships between plants and soil microorganisms. In this study, a factorial experiment was conducted to investigate the effects of Chinese fir (Cunninghamia lanceolata) planting and different levels of P addition (0, 1.95, 3.9, 7.8 and 15.6 g P·m-2·a-1) on soil microbial biomass and extracellular enzyme activities. The results showed that planting Chinese fir planting significantly altered soil microbial biomass and C- and N- and P-related extracellular enzyme activities, but the effects were dependent on P addition levels. Without P addition, Chinese fir planting significantly reduced soil nutrient availability and pH, which led to the aggravation of P limitation and lower soil microbial biomass. P addition relieved P limitation, and reduced soil acid phosphatase (ACP) activities by 30.0%, 30.5%, 35.3% and 47.1% with the increasing P addition level (1.95, 3.9, 7.8 and 15.6 g P·m-2·a-1). Under three P addition levels (1.95, 3.9 and 7.8 g P·m-2·a-1), the negative effects of Chinese fir planting on soil microbial growth were alleviated. Under the high P addition level (15.6 g P·m-2·a-1), the negative effects of Chinese fir planting on soil microbial growth occurred again due to soil N limitation. Taken together, Chinese fir planting and soil P availability generally affected soil microbial biomass and extracellular enzyme activities, and changed P limitation.