Abstract Soil-borne diseases of tobacco roots and stems, caused by pathogens including Ralstonia solanacearum (bacterial wilt), Phytophthora parasitica var. nicotianae (black shank), and root-knot nematodes ( Meloidogyne spp.), represent critical threats to tobacco cultivation. However, information regarding alterations in rhizosphere soil properties and microbial communities following co-infection by multiple soil-borne pathogens remains limited for tobacco-growing regions in Luxi County, Honghe Prefecture, Yunnan Province, China. This study therefore investigated rhizosphere soils collected from healthy and diseased tobacco plants in Baishui Town. Eighteen soil physicochemical parameters and six enzyme activities were measured. Bacterial and fungal community compositions were analyzed using high-throughput sequencing targeting the 16S rDNA V4 region and the ITS1 region, respectively. Relationships between environmental factors and microbial community shifts were further explored using redundancy analysis (RDA) and Spearman correlation analysis. Results demonstrated that, compared with healthy tobacco plants, various physicochemical factors and enzyme activities in the rhizosphere soils of diseased plants were significantly elevated. Bacterial community diversity and species richness in diseased tobacco rhizosphere soils were significantly altered by pathogen infection. Specifically, the relative abundance of the phylum Proteobacteria significantly decreased by 18.20%, whereas Chloroflexi and Gemmatimonadetes significantly increased by more than two-fold. The fungal phylum Chytridiomycota significantly decreased by 72.68%. At the genus level, the beneficial bacterium Sphingomonas significantly decreased by 36.13%, and the beneficial fungus Penicillium significantly decreased by 90.59% in relative abundance. Conversely, pathogenic fungi Fusarium , Phoma , and Plectosphaerella significantly increased by 3-fold, 5-fold, and 3-fold, respectively. RDA and Spearman correlation analyses revealed that variations in rhizosphere microbial communities were significantly and positively correlated with elevated soil pH, organic matter, total nitrogen, available nitrogen, total phosphorus, manganese content, and the activities of peroxidase and protease, while significantly and negatively correlated with decreased total potassium, available potassium, and boron contents. Our findings indicate that the imbalance (or alternatively: dysbiosis of microbial communities coupled with the disruption ) of soil physicochemical properties, enzyme activities, and microbial community structure constitutes a typical characteristic of tobacco rhizosphere soils subjected to multiple pathogen co-infections in this region.

Pcc is one of the key pathogenic factors responsible for destructive soft rot in konjac. To date, the assembly and functional adaptation of the plant endophytic microbiome under Pcc stress remain poorly understood. Here, we found that Pcc stress leads to rapid reorganization of the endogenous microbiome in multiple organs of both susceptible and resistant konjac plants. Under Pcc stress, the negative interactions within the bacterial-fungal interdomain network intensified, suggesting an increase in ecological competition between bacterial and fungal taxa. We further discovered that the relative abundance dynamics of the classes Dothideomycetes and Sordariomycetes, as core fungal taxa, changed in response to Pcc stress. By isolating culturable microorganisms, we demonstrated that 46 fungal strains strongly inhibited the growth of Pcc. This implies that endophytic fungal taxa in konjac may protect the host plant through ecological competition or by inhibiting the growth of pathogenic bacteria. Metagenomic analysis demonstrated that microbial communities associated with resistant Amorphophallus muelleri exhibited unique advantages over susceptible Amorphophallus konjac in enhancing environmental adaptability, regulating plant immune signaling, strengthening cell walls, and inducing defense responses. Our work provides important evidence that endophytic fungal taxa play a key role in the host plant's defense against necrotizing bacterial pathogens.

Introduction:The seeds of Amorphophallus muelleri represent a unique category of herbaceous seeds that arise from triploid apomixis. They necessitate an exceptionally protracted maturation phase of 8 months, followed by a dormancy period of 4 months, before they can germinate and give rise to fully formed new plants. Currently, the connection between endophytic microbial communities in A. muelleri seeds and the host plant's development is largely unexplored. Methods:Herein, we analyzed the temporal dynamics of the endophytic bacterial and fungal communities from seed germination to seedling establishment (seven stages) through amplicon sequencing. Results and discussion:The results showed that plant developmental stage explained the large variation in endophytic bacterial and fungal communities in A. muelleri and that multiple microbial attributes (e.g., α, β-diversity, community composition, and bacterial and fungal ecological networks) are driven by the developmental state of A. muelleri. Metagenomic analyses further indicated that the four stages after rooting have higher microbial functional diversity. Microbial functional genes involved in cell wall/membrane/envelope biogenesis, inorganic ion transport and metabolism, and carbon degradation were abundant in A. muelleri seeds from Stage 1 to Stage 3 (before rooting). From Stage 4 to Stage 7 (after rooting), microbial functional genes involved in the carbon, nitrogen and phosphorus cycles, starch and sucrose metabolism, and energy production and conversion were more abundant. Coincidentally, more abundant Proteobacteria, and Basidiomycota taxa related to carbon degradation were found in stages 1-3, while more Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium and Stenotrophomonas taxa associated with nitrogen cycling and plant growth promotion were observed in stages 4-7. These findings have greatly improved our basic understanding of the assembly and functional adaptability of the endophytic microbiome during A. muelleri plant development and are helpful for the mining, development and utilization of functional microbial resources.

Background: The NAC transcription factor family of genes is one of the largest families of transcription factors in plants, playing important functions in plant growth and development, response to adversity stress, disease resistance, and hormone signaling. In this study, we identified the number of members of the Panax notoginseng NAC (PnNAC) gene family and conducted a comprehensive analysis of their physicochemical characteristics, chromosomal location, evolutionary features, and expression patterns both in different parts of the plant at different growth stages and in response to infection by Alternaria panax. Methods: The NAC gene family in P. notoginseng was identified using Hidden Markov Model (HMMER) and National Center of Biotechnology Information Conserved Domain Database (NCBI CDD), and their physicochemical properties were analyzed with Perl scripts. Phylogenetic relationships were determined using Clustal Omega and FastTree, and gene structures were visualized with an R script. Promoter regions were analyzed with PlantCARE, motifs with MEME and ggmotif, and transcriptome data were processed using Hical Indexing for Spliced Alignment of Transcripts (HISAT2) and HTseq. Results: This study identified 98 PnNAC genes in P. notoginseng, analyzed their characteristics (protein lengths 104–882 aa, molecular weights 11.78–100.20 kDa, isoelectric points 4.12–9.75), location (unevenly distributed on 12 chromosomes, no tandem repeats), evolution, and expression patterns (distinct in different parts, growth stages, and after A. panax infection). Conclusions: PnNAC plays an important role in the growth and development of P. notoginseng and in its response to A. panax. PnNAC could be a candidate gene for further research on and functional analysis of P. notoginseng disease resistance.

Strawberry (Fragaria × ananassa) is a nutritionally valuable and widely popular fruit worldwide. Drought stress is a key factor affecting strawberry production; however, previous studies lacked in depth research on the physiological, biochemical, and molecular regulatory mechanism differences among various strawberry varieties. This study systematically examined the physiological and molecular responses of two cultivars, ‘Benihoppe’ and ‘Kaorino’, to drought stress. Under mild and severe drought conditions, significant changes were observed in the growth parameters, chlorophyll concentration, antioxidant enzyme activity, and proline accumulation of the two varieties. with ‘Kaorino’ exhibiting superior drought tolerance compared with ‘Benihoppe’. Transcriptomic analysis identified 34,168 differentially expressed genes, including 9,665 upregulated and 24,503 downregulated genes. Venn analysis revealed 229 genes associated with proline biosynthesis, MDA accumulation, and antioxidant enzyme regulation. Transcription factors(TFs) expression was profiled using cross-referenced databases. A total of 8,379 DEGs encoding TFs were identified and classified into 47 TF families, some of which (e.g., NAC and WRKY) are known to be involved in drought stress responses. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses suggest that drought tolerance in strawberry involves the coordinated activation of stress signaling pathways, metabolic reprogramming, hormonal regulation, and defense-related biosynthetic routes, with both shared and cultivar-specific features. Metabolomic analysis revealed dynamic shifts in metabolites associated with osmotic adjustment, antioxidant defense, and hormonal regulation. The integrated multiomics approach enabled the construction of a gene–metabolite regulatory network, clarifying the interactions between gene expression and metabolite accumulation. Key pathways implicated in the drought response included the glycerophospholipid metabolism and MAPK signaling cascade. Lysophosphatidylglycerol acyltransferase(LPGAT) and Sucrose non-fermenting 1-related protein kinase 2(SnRK2) may be key genes affecting the drought resistance differences between two strawberry varieties. These findings provide valuable insights into the physiological and molecular mechanisms underlying drought adaptation in strawberries, offering a theoretical basis for breeding drought-resistant cultivars.

Strawberry root rot, caused by Neopestalotiopsis clavispora, is an emerging disease that seriously threatens the sustainable development of the strawberry industry. To develop eco-friendly control strategies, three antagonistic bacterial strains were screened from healthy strawberry plants and rhizosphere soils. Based on morphological characteristics, physiological and biochemical identification, and 16S rDNA sequence analysis, the isolates QY-4 and QJ-3 were identified as Bacillus velezensis, while TT-3 was identified as Bacillus subtilis. The results indicated that the cell-free culture filtrates of QY-4, QJ-3, and TT-3 significantly inhibited the hyphal growth of N. clavispora by disrupting cell membrane integrity, with inhibition rates of 63.29, 69.4, and 73.57%, respectively. Volatile organic compounds produced by these strains, evaluated using the plate pair method, effectively inhibited hyphal growth through aerial diffusion with inhibition rates of 47.76, 44.99, and 32.44%. Broad-spectrum antagonistic activity against several phytopathogenic fungi, including Colletotrichum acutatum, Alternaria alternata, and Botrytis cinerea, was observed with inhibition rates ranging from 50.37 to 78.88%. Through the antibiotic marker method, the labeled strains were shown to translocate from roots to stems and leaves following root irrigation treatment, establishing stable colonization in both strawberry tissues and rhizosphere soils. The application of these antagonistic strains significantly alleviated root rot symptoms and markedly reduced the disease index, with values of 36.98, 42.19, and 27.92, corresponding to disease control efficiencies of 56.28, 50.12, and 67%, respectively. Additionally, significant enhancement of superoxide dismutase, peroxidase, and catalase was observed in leaves, indicating the induction of host resistance. These findings demonstrate the dual role of QY-4, QJ-3, and TT-3 as biocontrol agents, by combining antifungal activities with resistance induction, thus offering promising candidates for the sustainable management of strawberry root rot.

The complete genome sequence of a positive-sense single-stranded RNA (+ ssRNA) virus, Rhizoctonia beny-like virus 1 (RBLV1), isolated from binucleate Rhizoctonia AG-A strain A46, was determined. The RBLV1 genome is 10,280 nt in length and contains a short stretch of adenines at the 3′ terminus. It contains a single open reading frame (ORF) encoding a 376.30-kDa protein with viral helicase and RNA-dependent RNA polymerase (RdRp) motifs. The encoded protein exhibited the highest sequence similarity to Rhizoctonia cerealis beny-like virus 0928-1 (RcBeLV 0928-1, 45.25%), with a sequence coverage of 63%. Phylogenetic analysis based on ORF protein sequences revealed that RBLV1 is a novel unclassified mycovirus.

Konjac seeds of Amorphophallus muelleri are produced through a unique form of apomixis in triploid parthenogenesis, and typically require a longer maturation period (approximately 8 months). To date, the relevant functions of endophytic microbial taxa during A. muelleri seed development and maturation remain largely unexplored. In this study, we analyzed the functional adaptability and temporal dynamics of endophytic microbial communities during three stages of A. muelleri seed maturation. Through metagenomic sequencing, we determined that the functions of the endophytic microbiome in A. muelleri seeds were driven by the seed maturation status, and the functions of the microbial communities in the seed coats and seeds differed significantly. The species annotation results show that Proteobacteria, Actinobacteria, Ascomycota, and Basidiomycota were the dominant bacterial and fungal communities in A. muelleri seeds at different maturation stages. The KEGG and COG functional gene annotation results revealed that the seed samples during the three maturation stages had higher KO functional diversity than the seed coat samples, and the COG functional diversity of the green and red seed samples was also significantly higher than that of the seed coat samples. At different maturation stages, microbial functional genes involved in energy production and conversion as well as carbon fixation were enriched in the A. muelleri seed coats, while microbial functional genes involved in signal transduction mechanisms, amino acid transport and metabolism, carbohydrate metabolism, and lipid metabolism were more highly expressed in the seeds. Moreover, in the middle to late stages of seed maturation, the microbial functional genes involved in the biosynthesis of resistant compounds such as phenols, flavonoids, and alkaloids were significantly enriched to enhance the resistance and environmental adaptation of A. muelleri seeds. The results verified that the functions of the endophytic microbial communities change dynamically during A. muelleri seed maturation to adapt to the current needs of the host plant, which has significant implications for the exploration and utilization of functional microbial resources in A. muelleri seeds.

Abstract In this study, the complete genome of a positive sense single-stranded RNA (ssRNA) virus designated binucleate Rhizoctonia beny-like virus 1 (BRBLV1) was determined. This virus was isolated from binucleate Rhizoctonia AG-A strain A46, and was found to exhibit genomic organization similar to that of Rhizoctonia solani beny-like virus 1 (RsBLV1). The 10,280 nt genome of BRBLV1 was found to contain a poly(A) tail and one open reading frame (ORF) encoding a polypeptide 376.30 kDa in size that includes N-terminal helicase, C-terminal helicase, and RNA-dependent RNA polymerase (RdRp) domains. This ORF exhibited the greatest sequence identity to RsBLV1 (44.61%), with a sequence coverage of 59%. Phylogenetic analyses additionally confirmed that BRBLV1 and RsBLV1 clustered together in a clade that was separate from clades containing benyviruses, alphaendornaviruses, and other beny-like viruses. The length of the BRBLV1 and RsBLV1 genomes was also greater than that for any other known beny-like viruses characterized to date. This suggests that BRBLV1 represents a novel mycovirus, and that BRBLV1 and RsBLV1 should be classified in a new mycoviral taxon closely related to the Benyviridae family.

Biochar is known to have soil-improving effects and has been applied in agricultural production. Continuous cropping of flue-cured tobacco is common due to limited land resources, which can lead to soil obstacles that negatively affect yield. This study aimed to use agricultural waste as raw material to prepare biochar, to improve soil and alleviate continuous cropping obstacles. A 7-year continuous cropping filed of flue-cured tobacco variety ‘yunyan 87′ in Luoshui Town was selected, with four treatments, compound fertilizer (T1) alone, and biochar with 100, 75 and 50% amount of compound fertilizer (T2, T3 and T4), respectively. The physicochemical properties of biochar were studied, its structure was observed under an electron microscope. Its effects with reduced compound fertilizer application on agronomic traits, tobacco yield, soil enzyme activity and rhizosphere bacteria communities were investigated. In the results, biochar increased the tobacco yield (by 10.84%) compared to the same amount of fertilizer without biochar. Biochar application with 75% compound fertilizer (T3) could increase leaf area and yield of flue-cured tobacco significantly. T3 treatment had little effect on the phenoloxidase activity in the rhizosphere soil, however it significantly enhanced the activities of peroxidase, protease and urease by 56.84%, 50% and 11.94% respectively, compared with the T1 treatment. The α -diversity was the highest Under the T1 treatment. Biochar application (T2–T4) increased the soil pH significantly. Under biochar application with the decrease of compound fertilizer, the relative abundance of Proteobacteria improved whereas the abundance of unidentified_Bacteria, Chloroflexi and Gemmatimonadetes decreased. Overall, the study provided evidence that the use of biochar with reduced amount of compound fertilizer could effectively improve the growth, soil quality and alleviate the negative effects of continuous cropping on tobacco. These findings provided a reference for the potential use of agricultural waste and promoting sustainable crop production.

Biochar is a carbon-rich soil conditioner produced from pyrolysis of biomass, it has been widely used to enhance soil quality because of its physical adsorption as well as water and fertilizer conservation functions. This work aimed to improve the soil quality of continuously cropped flue-cured tobacco fields using biochar prepared from agricultural waste. To explore the impact of reduced compound fertilizer with biochar application on nutrients, phenolic acid contents and fungi diversity in the rhizosphere soil, 4 treatments were set: regular compound fertilizer application (T1), and biochar with reduced compound fertilizer in different proportions (T2, T3, T4, with 100, 75, 50% of compound fertilizer, respectively). The physicochemical properties of the prepared biochar were characterized and observed using electron microscopy. The results indicated that, a noticeable increase in the content of soil organic matter (SOM) and soil organic carbon (SOC) in T2 treatment compared to T1 treatment. Moreover, T2 treatment demonstrated a significant improvement in the contents of alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and available potassium (AK), with increases of 9.29%, 15.85% and 25.42% compared to T1 treatment, respectively. While a gradual decrease in soil AN, AP, and AK content was observed with the reduction of compound fertilizer application (T2–T4), there was no obvious difference between T3 and T1. For total phenolic acid, the content in T2 treatment significantly decreased by 35.99% compared to T1 treatment, while T3 and T4 treatments showed significant reductions of 15.30 and 18.73% respectively, compared to T2 treatment. Biochar application could enhance the fungal community’s abundance and diversity in the rhizosphere soil. Fungal community exhibited the highest richness under T3 treatment, while the relative abundance of Fusarium and Mortierella reduced as the decrease of compound fertilizer (T2–T4). In conclusion, the reduced compound fertilizer with biochar application could reduce nutrient loss, phenolic acids accumulation, and improving the abundance of fungal community in the rhizosphere soil. This paper provides a reference for biochar combined with compound fertilizer to improve soil from the regulation of allelochemicals and soil fungi.

Microbial necromass carbon (MNC) is an essential component of soil organic carbon (SOC). The contribution of MNC to SOC has been acknowledged in previous studies; however, there is a gap in understanding the effect of fertilization treatment on MNC, especially in rhizosphere soil. In the current study, four types of treatments were selected to examine the impact of fertilization on MNC and its contribution to SOC, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). These treatments included conventional compound fertilizer (Control), conventional compound fertilizer combined with microbial fertilizer (T1), a mixture of 75% conventional compound fertilizer with microbial fertilizer (T2), and microbial fertilizer (T3). The results indicated that the type of fertilization treatments and sampling time affected the MNC accumulation, especially fungal necromass carbon (FNC), and its contribution to SOC. Combined application of microbial and compound fertilizers increased the amino sugar (TAS) and MNC contents, especially during the harvest period (3.47-27.35%). The accumulation of MNC (5.13-9.42 g kg-1) and its contribution to SOC (38.03-50.49%) increased with the growth period, and the ratios of FNC to SOC, POC, and MAOC were about three times than that of the bacterial necromass carbon (BNC). Further, the regression analysis revealed a higher POC accumulation than MAOC. In addition, POC was positively correlated with MNC and FNC (p < 0.05). RDA analysis exhibited that microbial biomass phosphorus, phosphorus acquiring enzyme activity, POC, and the ratio of fungal to bacterial biomass had significant effects on amino sugar and MNC accumulation and contribution (p < 0.05). Further, T2 was found to be beneficial for FNC accumulation, promoting POC formation and increasing SOC content in tobacco planting soil. Taken together, our findings suggest that fertilization treatments affected microbial activity by regulating the N or P demand, leading to modulations in MNC accumulation and SOC storage.

The rhizosphere, directly influenced by root systems of plant, plays a significant role in plant-microbe interactions, which in turn directly affect the plants. In this work, the dynamic characteristics of rhizosphere bacterial communities during the growth period of cultivated strawberry (Fragaria×ananassa ‘Hongyan’) were investigated, and the dominant bacterial species in different growth stages were identified. High-throughput sequencing (HTS) was employed to obtain operational taxonomic unit (OTU) abundance, bacterial community diversity, and abundance of rhizosphere bacteria at five growth stages of strawberry: growth period (A1.1), budding period (A2.2), flowering period (AB3.2), fruiting period (AB4.1) and mature fruit period (AB5.2). The composition and abundance of bacterial communities structure were analyzed using the unweighted pair group method with arithmetic means (UPGMA) cluster analysis. The result indicated that, in the flowering stage the bacterial community exhibited the highest diversity and richness, while the bud stage had the least. The flowering stage showed a greater specific bacteria species in the strawberry rhizosphere, followed by growth, mature and harvest stages, and the lowest in the bud stage. The main dominant phyla were Actinobacteria, Proteobacteria and Acidobacteria, accounting for over 70% of the total bacterial abundance. The main dominant genera were Alcanivorax, Kaistobacter, Marinobacter and Candidatus Nitrososphaera. The bacterial abundance similarity was relatively high in the growth and harvest stages, as well as in flowering and mature stages, while it differed greatly from that of the bud stage. In conclusion, the difference in bacterial diversity between bud stage and flowering stage was the greatest, with the Chao1 index and Shannon index increased by 79.35 and 6.74%, respectively. The rhizosphere bacterial community richness and diversity were highest at the flowering stage (AB3.2), with 198 specific OTUs accounting for 7.48% of the total OTUs. At the phylum level, the bacterial abundance of Proteobacteria, Acidobacteria and Actinobacteria were greatly affected by the developmental stage. These findings suggest that the bacterial diversity of strawberry rhizosphere will change with the growth stage.

Rhizoctonia solani is a widely disseminated phytopathogen that is found in the soil and is capable of harming many important species of crops. Here, analysis of the R. solani AG-4 HG III strain A14 led to the identification of a novel mycovirus assigned the tentative name "Rhizoctonia solani partitivirus A14" (RsPV-A14), which was subjected to sequencing and associated analyses. This approach revealed that RsPV-A14 harbored two dsRNA segments, 2022 bp (dsRNA1) and 1905 bp (dsRNA2) in length. dsRNA1 was found to contain a single open reading frame (ORF1) that codes for a 622-amino-acid protein with conserved RNA-dependent RNA polymerase (RdRp) motifs, and dsRNA2 was found to contain an ORF (ORF2) that is predicted to code for a 558-amino-acid capsid protein (CP). BLASTp analysis using the putative RdRp of RsPV-A14 showed sequence similarity to partitiviruses, including Rosellinia necatrix partitivirus 7 (50.53% identity), an unclassified partitivirus. Phylogenetic analysis based on RdRp protein sequences suggested that RsPV-A14 is a novel member of the family Partitiviridae.

The unreasonable application of chemical fertilizer as abiotic stress can affect the production of reactive oxygen species (ROS) and the synthesis of related substances, thereby affecting the antioxidant systems mediated by Ascorbate-glutathione (AsA-GSH) cycle, Methyl jasmonate (MeJA), S-Nitrosothiols (SNOs) in tobacco plants. Up to now, further research is needed on the impact of chemical fertilizer application on the above antioxidant system in tobacco plants. In this study, the flue-cured tobacco cultivar ‘Yunyan 87’ ( Nicotiana tabacum L.) was used as the material. The content of non-enzyme antioxidants and related enzyme activities of AsA-GSH cycle system, the content of MeJA and SNOs in tobacco leaves, as well as tobacco yield were detected, to study the effects of different amount of fertilizer application (T1 = 30 g/plant, T2 = 45 g/plant, T3 = 60 g/plant) on related indicators of antioxidant system. The results indicated that the content of non-enzymatic antioxidants (AsA and GSH) and the activities of related enzymes in the AsA-GSH cycle, including ascorbate peroxidase (APX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) exhibited first increased and then decreased with increasing amount of fertilizer application. Most of the treatments showed significant differences. T3 treatment markedly reduced MeJA content compared to T1 and T2 treatments. With the increase of fertilizer application, the content of SNOs and the activity of S-Nitrosoglutathione reductase (GSNOR) in tobacco leaves exhibited an initial increase, followed by a decrease, and finally increasing trend, with notable differences among most treatments. Tobacco yield markedly decreased in the T1 treatment compared to the T2 and T3 treatments; however, no obvious difference between T2 and T3 treatments. Altogether, the fertilizer application of T1 (30 g/plant) was too low, which was not conducive to the synthesis of antioxidant substances in tobacco leaves. However, the fertilizer application amount of T3 (60 g/plant) was attributed to excessive application, which caused high salt stress on the growth of tobacco plants. This study provides a basic reference for optimizing fertilizer application in tobacco production.

Microbial necromass carbon (MNC) is an important component of soil organic carbon (SOC). Although the contribution of MNC to stable SOC pool has been recognized, the response of MNC to fertilization in flue-cured tobacco growing soils is rarely studied. In this study, microbial biomarkers were extracted from rhizosphere soil and used to measure the relationship between the soil microbial community composition (using phospholipid fatty acids, PLFAs) and MNC (using amino sugars), and the contribution of MNC to SOC and its fractions (including particulate and mineral-associated organic carbon (POC and MAOC)) under compound and microbial fertilizer addition. The results showed that the accumulation of amino sugars and MNC increased with the growth period and was affected by the limitation of microbial resources. Compared with other treatments, compound fertilizer reduction combined with microbial fertilizer treatment increased the content of amino sugars and MNC, especially during the harvest period. The contribution of MNC to SOC varied from 38.03% to 50.49%, while the contribution of fungal necromass carbon (FNC) to SOC, POC, and MAOC was approximately three times that of bacterial necromass car-bon (BNC). The content of MNC and FNC increased significantly with the increase of POC, and POC accumulation rate is greater than MAOC. By forming POC, the contribution of fungal necro-mass carbon to SOC was promoted. While the relationship between MAOC and BNC was closer than that of FNC. Hence, bacterial necromass carbon was involved in SOC turnover while fungal necromass carbon dominantly contribute to SOC accumulation. In addition, microbial biomass and microbial community structure composition are important determinants of amino sugars and MNC. Summarizing, these results provided a new idea for the microbial mechanism of controlling carbon persistence in tobacco planting soil, and the POC and MAOC components, and microbial fertilizer partially replace compound fertilizer should be considered.

利用植物根际微生物防控土传病害,已成为植物保护的重要手段.在根际病原菌的胁迫下,根际微生物能够有效帮助植物提高抗病性,使其免受病原菌的侵染.对近年来根际生防微生物在土传病害防治中的应用和作用机制进行综述,并以此为基础,结合当前研究现状,对根际微生物防治土传病害研究的热点方向进行展望,以期高效、绿色、安全地利用根际微生物防控土传病害,为农田病害防控实现绿色、可持续发展提供参考.

为研究低温条件下不同浓度CaCl2浸泡处理对蓝莓果实采后贮藏品质的影响,该试验以"夏普蓝"蓝莓为材料,贮藏过程中每3d对蓝莓果实的相关生理指标、抗氧化相关酶活性、类黄酮、总酚及花青素含量进行测定.结果表明:与对照(CK)相比,CaCl2处理能有效降低采后蓝莓果实的腐烂率,减缓失重,抑制果实硬度和可溶性固形物含量的下降,显著提高蓝莓果实过氧化物酶活性,抑制丙二醛含量的上升,延缓类黄酮、总酚和花青素含量的下降.

为探讨昆明主城区城市绿化中菊科观赏植物的应用现状,采用选点调查方法,对昆明主城区的20块绿地进行实地调研.结果显示,应用于昆明主城区绿化中的菊科观赏植物有27种,隶属24属,草本类多于木本类,观花类占所有种的1/2以上,而乡土菊科观赏植物品种尚少.此外,分析了昆明主城区城市绿地中菊科观赏植物的开花性状、应用广泛程度、布局形式、耐寒性等,同时提出菊科植物应用和研究的相关建议.

To explore the composition and changing patterns of microbes in the rhizosphere soils of tobacco over different growth stages, we extracted samples from rhizosphere soils at the resettling stage, vigorous growing stage, budding stage, mature stage and the decaying stage in the tobacco lifecycle. The V4–V5 fragments of the 16S rDNA and the ITS1 fragments of the 18S rRNA have been sequenced by Illumina MiSeq, a high-flux sequencer. A total of 8031 bacterial OTUs and a total of 1983 fungal OTUs have been tested. Both the Chao1 index and Shannon index of bacteria in the rhizosphere soil samples change in a V-shaped pattern over the five growth stages, which peak at the budding stage and increase at the decaying stage after a period of falling. In the growing cycle of tobacco, the dominant bacteria include γ-Metamorphomycetes, α-Metamorphomycetes, Actinomycetes and Acidobacteria , and the dominant fungal phyla include Crustacea, Ascomycetes, Agaricomycetes, IS-s-Retroconis sp XAE_090 . The sufficiency and diversity of microbial communities in the rhizosphere soil samples range greatly over the five growth stages. This study lays a theoretical foundation supporting further explorations into the changing rules of microbial communities in the rhizosphere soil of tobacco growth and the relationship between microbial communities and tobacco soil-borne diseases.