The purpose of this study was to investigate the mechanism and efficacy of Lvnonglin ^®41 compound microbial fertilizer in mitigating black pepper continuous cropping obstacles from the perspectives of soil nutrients, microbial community structure and diversity, so as to provide technical strategies for the industrial cultivation of black pepper in Hainan. Field experiments were conducted on a plot with a history of severe black pepper Fusarium wilt. Four treatments were designed: water control (CK), Lvnonglin^® 41 compound microbial fertilizer (LNL41), compound microorganisms (CM), and bacterial fertilizer nutrient substrate (NS). The incidence of Fusarium wilt in the rhizosphere, plant growth and soil nutrients were measured. Using 16S rDNA sequencing technology, the differences in the occurrence of black pepper Fusarium wilt and the bacterial community structure in the rhizosphere soil under LNL41 application were explored. The results showed that compared with CK, all treatments exhibited certain effects, with the LNL41 treatment being the most effective. Soil nutrient indicators in the LNL41 and CM treatments were significantly higher than those in CK. The increases in chlorophyll content, spike length and 1000-grain weight under LNL41, CM and NS treatments reached 26.12%-67.87%, 6.20%-18.33% and 1.48%-6.44%, respectively. The incidence rates at different growth stages in the LNL41 treatment were 2.67%-15.67%, with control efficacies of 81.64%-90.06%. The Ace and Chao1 indices of rhizosphere soil bacteria increased by 12.82%-20.28% and 12.89%-18.78%, respectively, and the Shannon diversity index increased by 1.05%-3.53%, while the Simpson index showed no significant difference among treatments. At the order level, Chitinophagales, Rhizobiales and Burkholderiales were the dominant bacterial orders. At the genus level, Gaiella, P3OB 42, Lactobacillus, Pseudolabrys and Terrimonas were the dominant bacterial genera. The abundances of the common dominant genus Bacillus and Candidatus Omnitrophus were similar across treatments. Linear discriminant analysis (LEfSe) results indicated the presence of six indicator bacterial taxa in the LNL41 treatment. Ellin6067 and Tepidisphaera showed significant or highly significant positive correlations with soil pH, organic matter, available potassium, ammonium nitrogen and available phosphorus. Network analysis further revealed that the LNL41 treatment enhanced the complexity and stability of the soil bacterial co-occurrence network. Bugbase functional prediction demonstrated that the abundance of stress tolerant functional groups in the LNL41 treatment increased by 5.38 percentage points, while it decreased by 10.43 and 7.25 percentage points in the CM and NS treatments, respectively. LNL41 significantly improved the ratio of soil nutrients, thereby enhancing the structure and functional characteristics of the soil bacterial community, stimulating bacterial stress tolerance functions, promoting black pepper growth, and reducing the incidence of Fusarium wilt.

Sugarcane is a crucial crop for both sugar and bioenergy production, with sugar accumulation and cell wall formation being critical biological processes during its growth and development. This study employed transcriptome sequencing on the ROC22 sugarcane variety, collecting samples from leaves at the 1^st, 3^rd, and 5^th nodes, bark tissues at the 3^rd, 5^th, 7^th, 11^th, and 17^th internodes, and pith tissues at the 1^st, 3^rd, 5^th, 7^th, 11^th, and 17^th internodes. A comprehensive analysis of 42 transcriptome datasets using Weighted Gene Co-expression Network Analysis (WGCNA) revealed 34 distinct co-expression modules. Notably, the midnight blue, purple, and magenta modules demonstrated significant and specific correlations with the 1^st node leaf, 7^th internode pith, and 5^th internode bark, respectively. KEGG and GO enrichment analyses indicated that the modules participated in tissue-specific biological processes. The blue, yellow, turquoise, and black modules were primarily expressed in leaves, young pith, immature internodes, and bark, respectively. Within the blue module, key enzymes implicated in photosynthesis were identified, such as LFNR1, PSAK, PETE, PSAN, and NADP-ME4, which are essential for the initial production and accumulation of sugar in sugarcane. The yellow module featured a sucrose metabolism network centered on SUS4, including SWEET2 and an array of sugar transport-related enzymes and proteins, suggesting that the pith serves as the primary site for sugar transport and storage in sugarcane. The turquoise module contained glycoproteins and enzymes potentially involved in the synthesis and modification of the primary cell wall. Meanwhile, transcription factor NST1, which regulates secondary cell wall biosynthesis, along with other cell wall-modifying enzymes in the black module, may contribute to cell wall deposition in the cortex, providing mechanical strength and a barrier against external stresses for sugarcane. The findings would provide important references for studying the regulatory networks of sugar accumulation and cell wall formation in sugarcane.