Continuous cropping obstacles (CCOs) severely constrain tobacco yield and quality, yet the mechanisms by which they influence rhizosphere microbial communities remain poorly understood. This study investigated the predominant tobacco cultivar K326 in Yunnan Province to elucidate soil-microbe interactions under CCOs. We examined how CCOs shape rhizosphere environments and microbial dynamics by integrating soil chemical analyses with molecular ecological techniques. The CC led to significant alterations in soil properties, including declines in pH, organic matter (OM), organic carbon (OC), and total nitrogen (TN), along with variable trends in available phosphorus (AP), potassium (AK), and ammonium (NH4 +-N). The composition of water-stable aggregates also shifted notably with cropping duration. Bacterial alpha diversity increased progressively with CC, whereas fungal diversity peaked early and declined thereafter. Constrained principal coordinate analysis (CPCoA) revealed distinct clustering among treatments, with fungal communities showing greater sensitivity to CCO-induced stress. Taxonomic analysis revealed a decreases in Bacteroidota but an enrichments of Gemmatimonadota and Planctomycetota, accompanied by reductions in beneficial bacterial genera, including Streptomyces and Sphingomonas. In contrast, fungal communities exhibited declines in Dothideomycetes and Alternaria, while Sordariomycetes and Penicillium became more dominant. Co-occurrence network analysis showed that microbial interactions and network complexity initially strengthened under short-term CC but weakened with prolonged cultivation, suggesting a gradual restructuring of community stability. Functional predictions further indicated that, although nutrient cycling potential was initially higher in non-cropped soils, processes such as nitrification, cellulolysis, and saprotrophic activity were progressively enhanced under CC. These findings deepen our understanding of rhizosphere ecological responses to CCOs and provide a theoretical basis for microbiome-informed nutrient management strategies to sustain tobacco productivity over the long term.

IntroductionCitrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a major threat to citrus production worldwide, resulting in significant losses in yield and fruit quality. This study investigates the differential responses of endophytic microbial communities to Xcc infection in citrus cultivars with distinct resistance levels, specifically comparing the highly susceptible Citrus reticulata cv. ‘Orah’ and the more resistant Fortunella crassifolia cv. ‘Cuimi’. Through high-throughput amplicon sequencing, we characterized the bacterial and fungal communities in both cultivars before and after Xcc inoculation.ResultsThe results revealed distinct shifts in microbial diversity, with bacterial community diversity largely maintained in resistant cultivars but significantly reduced in susceptible ones following Xcc infection. Conversely, fungal community richness decreased in both cultivars post-inoculation, with notable cultivar-specific changes in the relative abundance of key genera. Notably, Lysobacter emerged as the only bacterial genus that significantly increased in abundance in the resistant cultivar under pathogen pressure, highlighting its potential as a key biocontrol agent. Further, we identified several fungal genera, including Penicillium and Aspergillus, which proliferated in susceptible plants under pathogen pressure. The study also isolated and identified a Lysobacter antibioticus GJ-6 strain with potent antagonistic activity against Xcc, offering insights into its potential role in enhancing disease resistance.ConclusionsThis work provides a comprehensive understanding of how endophytic microbiomes differ between resistant and susceptible citrus cultivars, suggesting new avenues for developing sustainable biocontrol strategies to manage citrus canker. These findings underscore the potential of endophytes in mitigating plant diseases and advancing the application of microbiome-based interventions in agriculture.

BackgroundPlasmodiophora brassicae is an ever-increasing threat to cruciferous crop production worldwide.Aims and methodsThis study investigated the impact of pre-soil fumigation with ammonium bicarbonate (N) and lime (NB) to manage clubroot disease in Chinese cabbage through 16S rRNA gene amplification sequencing.ResultsWe found that soil fumigation with N and NB suppressed disease incidence by reducing the soil acidity and population of P. brassicae in the rhizosphere. Minimum disease incidence and maximum relative control effect of about 74.68 and 66.28% were achieved in greenhouse and field experiments, respectively, under the combined application of ammonium bicarbonate and lime (LNB) as compared with N, NB, and control (GZ). Microbial diversity analysis through Miseq sequencing proved that pre-soil fumigation with N, NB, and LNB clearly manipulated rhizosphere microbial community composition and changed the diversity and structure of rhizosphere microbes compared with GZ. Bacterial phyla such as Proteobacteria, Bacteriodetes, and Acidobacteria and fungal phyla including Olpidiomycota and Ascomycota were most dominant in the rhizosphere of Chinese cabbage plants. Soil fumigation with N and NB significantly reduced the abundance of clubroot pathogen at genus (Plasmodiophora) level compared with GZ, while decreased further under combined application LNB. Microbial co-occurrence network analysis showed a highly connected and complex network and less competition for resources among microbes under combined application LNB.ConclusionWe conclude that for environmentally friendly and sustainable agriculture, soil fumigation with combined ammonium bicarbonate and lime plays a crucial role in mitigating Chinese cabbage clubroot disease by alleviating soil pH, reducing pathogen population, and manipulating the rhizosphere microbiome.

BackgroundBiochar application has become one of the most potential tools to improve soil fertility and plant growth for sustainable and eco-friendly agriculture. However, both positive and negative effects of biochar application have been recorded on plant growth and soil fertility.MethodsThis study investigated the impact of different application rates (0, 600, 900, 1200, and 1800 kg/ha) of biochar on the soil nutrient contents, accumulation of nutrients and dry matter in different plant parts, and growth of flue-cured tobacco plants under field conditions.ResultsResults demonstrated that soil organic carbon pool and carbon/nitrogen ratio were increased proportionally with the increasing dosage of biochar, 25.54 g/kg and 14.07 g/kg compared with control 17 g/kg and 10.13 g/kg, respectively. The contents of soil total nitrogen were also significantly increased after biochar application in the middle (1.77 g/kg) and late-growth (1.54 g/kg) stages of flue-cured tobacco than in control (1.60 g/kg and 1.41 g/kg, respectively). The contents of soil nitrate nitrogen were also higher under low (600 and 900 kg/ha) application rates of biochar and reduced when higher (1200 and 1800 kg/ha) dosages of biochar were applied. However, it was observed that varying application rates of biochar had no impact on soil ammonium nitrogen content during the growth period of flue-cured tobacco plants. The nutrient accumulation (N, P, K) in different parts of flue-cured tobacco plants was significantly increased under a low application rate of biochar, which enhanced the soil and plant analyzer development values, effective leaves number, growth, dry matter accumulation, and leaf yield of flue-cured tobacco. In contrast, the high biochar application rate (1200 and 1800 kg/ha) negatively impacted nutrient accumulation and growth of flue-cured tobacco.ConclusionConclusively, the optimum application of biochar (600 and 900 kg/ha) is beneficial for plant growth, soil fertility, accumulation of nutrients, and dry matter in different plant parts. However, excessive biochar application (> 900 kg/ha) could inhibit flue-cured tobacco plant growth. This study provides a theoretical foundation for biochar application in tobacco and other crop production to obtain agricultural sustainability and economic stability.

Ralstonia solanacearum is a devastating soilborne pathogen which poses significant yield and economic losses to tobacco production globally. The impact of R. solanacearum on rhizosphere bacteriome and soil physicochemical characteristics in resistant and susceptible tobacco cultivars is poorly understood. This study aims to determine the effect of R. solanacearum on soil physicochemical parameters and rhizosphere bacteriome of resistant (K326) and susceptible (Hongda) tobacco cultivars at various growth stages. Results demonstrated that the contents of available potassium and phosphorus, as well as soil pH were significantly increased in K326 soils (CK and T2) compared with Hongda (T1) after 21, 42, and 63 days post-inoculation (dpi) of R. solanacearum except for available nitrogen which showed an opposite trend. The qPCR results showed a significant decrease in R. solanacearum population in rhizosphere of K326 (T2) compared to the Hongda (T1) at 21 and 63 dpi than that after 42 dpi. The rhizosphere bacteriome analysis through 16S rRNA amplicon sequencing revealed that rhizosphere bacterial community composition was significantly different between two tobacco cultivars (Hongda and K326) and this effect was more prominent after 63 dpi (93 days after post-transplantation), suggesting that each cultivar recruits a unique set of bacterial communities. There was no obvious difference observed in the rhizosphere bacteriome of CK (K326) and T2 (K326), which might be attributed to the same genetic makeup and inherent resistance of K326 to bacterial wilt infection. Analysis of co-occurrence networks revealed that the microbial network in T1 (Hongda) was more complex than those in T2 (K326) and CK (K326), while the networks in CK and T2 were almost identical. The present research highlights the time-course relationship between environmental factors and rhizosphere bacteriome of tobacco cultivars showing different levels of resistance against R. solanacearum. Conclusively, studying the plant-soil-microbe interaction system in susceptible and resistant tobacco cultivars may enable us to develop effective integrated disease control plans for the healthy production of tobacco crops.

The predatory natural enemy Eocanthecona furcellata plays a crucial role in agricultural ecosystems due to its effective pest control measures and defensive venom. Predator venom contains serine protease inhibitors (SPIs), which are the primary regulators of serine protease activity and play key roles in digestion, development, innate immunity, and other physiological regulatory processes. However, the regulation mechanism of SPIs in the salivary glands of predatory natural enemies is still unknown. In this study, we sequenced the transcriptome of E. furcellata salivary gland and identified 38 SPIs genes named EfSPI1∼EfSPI38. Through gene structure, multiple sequence alignment and phylogenetic tree analysis, real-time quantitative PCR (RT-PCR) expression profiles of different developmental stages and different tissues were analyzed. RNAi technology was used to explore the gene function of EFSPI20. The results showed that these 38 EfSPIs genes contained 8 SPI domains, which were serpin, TIL, Kunitz, Kazal, Antistasin, Pacifastin, WAP and A2M. The expression profile results showed that the expression of different types of EfSPIs genes was different at different developmental stages and different tissues. Most of the EfSPIs genes were highly expressed in the egg stage. The EfSPI20, EfSPI21, EfSPI22, and EfSPI24 genes of the Pacifastin subfamily and the EfSPI35 gene of the A2M subfamily were highly expressed in the nymphal and adult stages, which was consistent with the RT-qPCR verification results. These five genes are positively correlated with each other and have a synergistic effect on E. furcellata, and they were highly expressed in salivary glands. After interfering with the expression of the EfSPI20 gene, the survival rate and predatory amount of male and female adults were significantly decreased. Taken together, we speculated some EfSPIs may inhibit trypsin, chymotrypsin, and elastase, and some EfSPIs may be involved in autoimmune responses. EfSPI20 was essential for the predation and digestion of E. furcellata, and the functions of other EfSPIs were discussed. Our findings provide valuable insights into the diversity of EfSPIs in E. furcellata and the potential functions of regulating their predation, digestion and innate immunity, which may be of great significance for developing new pest control strategies.

The plant rhizosphere is a major habitat for diverse microorganisms because of its heterogeneous microenvironment. It is well known that an imbalance in rhizosphere microorganisms has direct and indirect effects on soil fertility and plant health. In this study, we investigated the impact of Lysobacter antibioticus 13–6 seed coat treatment on the soil physicochemical properties, plant growth, and bacterial community composition of maize plants in both in vivo and in vitro experiments, using high-throughput amplicon sequencing of 16S rRNA. Under in vitro conditions, we determined that L. antibioticus 13–6 has the ability to solubilize P, hydrolyze cellulose, and synthesize indole acetic acid. Furthermore, under in vivo conditions, L. antibioticus 13–6 significantly improved the soil physicochemical properties and enhanced the root length, stalk height, dry weight of root and stalk, grain yield, and chlorophyll contents by successful colonization in the rhizosphere of maize plants. The results of high-throughput amplicon sequencing of 16S rRNA demonstrated that L. antibioticus 13–6 significantly changed the diversity and composition of the rhizosphere bacterial communities. The relative abundance of Gammaproteobacteria, Gemmatimonadetes, and Bacteroidetes at the phylum level and Streptomyces, Lysobacter, and Nitrospira at the genus level significantly increased in the rhizosphere of L. antibioticus 13–6 seed coat-treated plants. Co-occurrence networks analysis revealed that the rhizosphere of L. antibioticus 13–6 seed coat-treated plants had fewer negative correlations and less competition for resources among bacterial communities. Genome analysis of L. antibioticus 13–6 revealed that the genome of L. antibioticus 13–6 encodes genes related to indole acetic acid synthesis, chitinase decomposition, and P solubilization, making it one of the most potent plant growth-promoting bacteria. Overall, this study demonstrated the potential of L. antibioticus 13–6 as a promising seed coat bioagent for sustainable agriculture and to minimize the utilization of agrochemicals.

Clubroot disease, caused by Plasmodiophora brassicae, is a serious threat to Chinese cabbage (Brassica rapa subsp. pekinensis) production, which results in extensive yield losses. At present, clubroot control mainly depends upon pesticides, which provoke food-safety concerns, and the application of sole biocontrol agents cannot successfully control the disease. In this study, we investigated the effect of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 as sole strains, intra-/inter-genus co-culture, and microbial consortia on clubroot disease, plant growth, and rhizosphere bacterial diversity in a field experiment. The microbial consortia efficiently controlled the incidence of clubroot disease, with a biocontrol effect of about 65.78%, by decreasing the soil acidity and enhancing the yield (17,662.49 kg/acre). The high-throughput sequencing results demonstrated that the phyla Proteobacteria and Bacteroidetes were present in high relative abundance in the rhizosphere soil of the Chinese cabbage. Furthermore, Firmicutes was found as a unique phylum in the rhizosphere soil of CK-H and T1-T7, except for CK-D. The application of microbial consortia recovers the imbalance in indigenous microbial communities. Therefore, we conclude that microbial consortia can reduce the clubroot incidence in Chinese cabbage by decreasing the soil acidity and altering the diversity and structure of rhizosphere bacterial communities. This study highlights the potential of microbial consortia as an engineering tool to control devastating soilborne diseases in commercial crops.

Ralstonia solanacearum, the causative agent of bacterial wilt disease, has been a major threat to tobacco production globally. Several control methods have failed. Thus, it is imperative to find effective management for this disease. The biocontrol agent Bacillus amyloliquefaciens WS-10 displayed a significant control effect due to biofilm formation, and secretion of hydrolytic enzymes and exopolysaccharides. In addition, strain WS-10 can produce antimicrobial compounds, which was confirmed by the presence of genes encoding antimicrobial lipopeptides (fengycin, iturin, surfactin, and bacillomycinD) and polyketides (difficidin, bacilysin, bacillibactin, and bacillaene). Strain WS-10 successfully colonized tobacco plant roots and rhizosphere soil and suppressed the incidence of bacterial wilt disease up to 72.02% by reducing the R. solanacearum population dynamic in rhizosphere soil. Plant-microbe interaction was considered a key driver of disease outcome. To further explore the impact of strain WS-10 on rhizosphere microbial communities, V3-V4 and ITS1 variable regions of 16S and ITS rRNA were amplified, respectively. Results revealed that strain WS-10 influences the rhizosphere microbial communities and dramatically changed the diversity and composition of rhizosphere microbial communities. Interestingly, the relative abundance of genus Ralstonia significantly decreased when treated with strain WS-10. A complex microbial co-occurrence network was present in a diseased state, and the introduction of strain WS-10 significantly changed the structure of rhizosphere microbiota. This study suggests that strain WS-10 can be used as a novel biocontrol agent to attain sustainability in disease management due to its intense antibacterial activity, efficient colonization in the host plant, and ability to transform the microbial community structure toward a healthy state. IMPORTANCE The plant rhizosphere acts as the first line of defense against the invasion of pathogens. The perturbation in the rhizosphere microbiome is directly related to plant health and disease development. The introduction of beneficial microorganisms in the soil shifted the rhizosphere microbiome, induced resistance in plants, and suppressed the incidence of soilborne disease. Bacillus sp. is widely used as a biocontrol agent against soilborne diseases due to its ability to produce broad-spectrum antimicrobial compounds and colonization with the host plant. In our study, we found that the application of native Bacillus amyloliquefaciens WS-10 significantly suppressed the incidence of tobacco bacterial wilt disease by shifting the rhizosphere microbiome and reducing the interaction between rhizosphere microorganisms and bacterial wilt pathogen.

Clubroot disease caused by Plasmodiophora brassicae is a serious threat to Chinese cabbage (Brassica rapa L. ssp. pekinensis) production, which results in extensive yield losses. At present, clubroot control mainly depends on pesticides that have food safety concerns, and the application of sole biocontrol agents cannot successfully control the disease. In this study, we investigated the biocontrol effect of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 as sole strains, intra-/inter-genus co-culture, and microbial consortia on clubroot disease, plant growth, and rhizosphere bacterial diversity in a �eld experiment. This study showed that the application of microbial consortia e�ciently controls the incidence of clubroot disease with a biocontrol effect of about 65.78% by decreasing the soil acidity and enhancing the yield (2909.8 Kg/666.67 m 2 ). Alleviation of soil acidity results in the abundance and improved activity of bene�cial microorganisms in the rhizosphere soil of Chinese cabbage. High throughput sequencing results demonstrated that bacterial phyla Proteobacteria, Bacteroidetes, and Firmicutes were present in high relative abundance in the rhizosphere soil of Chinese cabbage. The application of microbial consortia recovers the imbalance of indigenous micro-ecology and alters the diversity and structure of rhizosphere bacterial communities. Therefore, we conclude that microbial consortia can reduce the clubroot incidence on Chinese cabbage by reshaping the rhizosphere microbiome and decreasing the soil acidity. This study suggested microbial consortia as a new engineering tool to control devastating soilborne disease in commercial crops.

Abstract Clubroot disease caused by Plasmodiophora brassicae is a serious threat to Chinese cabbage (Brassica rapa L. ssp. pekinensis) production, which results in extensive yield losses. At present, clubroot control mainly depends on pesticides that have food safety concerns, and the application of sole biocontrol agents cannot successfully control the disease. In this study, we investigated the biocontrol effect of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 as sole strains, intra-/inter-genus co-culture, and microbial consortia on clubroot disease, plant growth, and rhizosphere bacterial diversity in a field experiment. This study showed that the application of microbial consortia efficiently controls the incidence of clubroot disease with a biocontrol effect of about 65.78% by decreasing the soil acidity and enhancing the yield (2909.8 Kg/666.67 m2). Alleviation of soil acidity results in the abundance and improved activity of beneficial microorganisms in the rhizosphere soil of Chinese cabbage. High throughput sequencing results demonstrated that bacterial phyla Proteobacteria, Bacteroidetes, and Firmicutes were present in high relative abundance in the rhizosphere soil of Chinese cabbage. The application of microbial consortia recovers the imbalance of indigenous micro-ecology and alters the diversity and structure of rhizosphere bacterial communities. Therefore, we conclude that microbial consortia can reduce the clubroot incidence on Chinese cabbage by reshaping the rhizosphere microbiome and decreasing the soil acidity. This study suggested microbial consortia as a new engineering tool to control devastating soilborne disease in commercial crops.

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of flue-cured tobacco production which poses significant yield losses all around the world. In this study, we evaluated the rhizosphere microbiome of healthy and bacterial wilt-infected (diseased) flue-cured tobacco plants through amplification of V3-V4 and ITS1-5f variable regions of 16S and internal transcribed spacer (ITS) rRNA. The study was based on the location (Qujing, Shilin, and Wenshan), plant components (rhizosphere soil and roots), and sample types (healthy and diseased) to assess the diversity of bacterial and fungal communities. Bacterial and fungal communities present in roots primarily emanated from rhizosphere soil. Healthy flue-cured tobacco plants exhibit high microbial diversity compared to diseased plants. Among three variables, plant components significantly influence the diversity of microbial communities, whereas rhizosphere soil harbors higher microbial diversity than roots. Bacterial phyla Cyanobacteria and Proteobacteria were found in high relative abundance in roots and rhizosphere soil samples, respectively. As far as fungi is concerned, a high relative abundance of Ascomycota and Basidiomycota was found in both rhizosphere soil and root. Bacterial genera such as Bacillus, Bradyrhizobium, Ensifer, Neorhizobium, and Lysobacter related to plant growth promotion and disease suppressing abilities were dominant than fungal genera. Analysis of relative abundance at specie-level revealed that most fungal species are pathogenic to flue-cured tobacco and could provide a conducive environment for wilt infection. In conclusion, R. solanacearum significantly influences the microbial diversity of flue-cured tobacco plants and negatively affects the bacterial community composition. Altogether, our study demonstrates the complexity of bacterial and fungal communities that possibly interact with each other (microbe–microbe) and host (host–microbe). This cross-talk could be helpful for healthy flue-cured tobacco plant growth and to induce resistance against bacterial wilt disease.

玉米茎腐病是一种在世界玉米产区普遍发生的土传病害,根据病原菌的不同,玉米茎腐病分为细菌性茎腐病和真菌性茎腐病.玉米细菌性茎腐病病原主要有短小芽孢杆菌(Bacillus pumilus Meyer and Gottheil)[1]、玉米狄克氏菌(Dickeya ze-ae Samson et al.)[2]、铜绿假单胞杆菌(Pseudo-monas aeruginosa)[3]、成团泛菌(Pantoea agglom-erans)[4]等.玉米细菌性茎腐病导致玉米茎部腐烂并散发腥臭味,折断后导致玉米不能抽穗和结实,严重影响玉米产量[5].

研究旨在确定云南省蓝莓主产区发生的蓝莓根癌病病原菌种类,并进行田间防治药剂筛选.采集云南省蓝莓主产区蓝莓根癌病样品,通过发病症状、菌落形态观察、致病性测定、Biolog分析、16S rDNA序列分析比较进行系统鉴定.在发病严重的蓝莓基地采用噻霉酮、申嗪霉素等8种药剂进行田间防治试验.从蓝莓根癌病样品中分离、纯化获得的菌株L-11接种向日葵、番茄、蓝莓植株均能发病,且发病症状与田间症状相同,重新分离得到形态相同的菌株.16S rDNA序列分析和系统进化树结果表明,L-11菌株序列与根癌土壤杆菌(Agrobacterium tumefaciens)菌株Ell-7(登录号FJ613554.1)同源性高达97.65％,与根癌土壤杆菌处于同一分支上.菌株L-11利用ipt基因的特异性引物AtP3F/AtP3R能扩增出155 bp的特异性片段,进一步证实蓝莓根癌病由根癌土壤杆菌引起.田间药效试验结果表明,1.5％噻霉酮水乳剂对蓝莓根癌病有较好的防治效果,相对防效为52％.这是云南首次报道由根癌土壤杆菌引起蓝莓根癌病.

[目的]为研究大豆/白菜轮作及大豆秸秆还田对白菜根肿病的防治机理,并为今后该种植的绿色综合防控模式提供理论基础和技术支撑,探索防治白菜根肿病新方法提供可靠思路.[方法]利用实时荧光定量PCR、土壤微生物高通量测序和温室盆栽防效测定等方法,研究大豆/白菜轮作和大豆秸秆还田处理对白菜根肿病发生和根际微生物群落的影响.[结果]大豆与白菜轮作+大豆秸秆还田处理防治白菜根肿病的相对防效高达52.59％.大豆轮作处理的白菜根际土壤样品中每克土壤所含根肿菌休眠孢子数量减少了约77％,由原来的105个/克土壤减少到104个/克土壤.与白菜连作模式相比,大豆白菜轮作后根际土壤中细菌的OTU数,Ace,Chao1和Shannon指数均显著增加,表明大豆与白菜轮作模式能够增加根际土壤细菌的多样性.白菜连作根际土壤富集假单胞菌属(Pseudomonas)、葡萄球菌属(Staphylococcus)和阿克曼菌属(Akkermansia)等,使得根际土壤微生物种群较少,而大豆与白菜轮作的根际土壤中增加了根瘤菌、鞘氨醇单胞菌等有益微生物菌的群落多样性.在真菌属水平群落结构的测序结果发现,大豆白菜轮作和大豆/白菜轮作+大豆秸秆还田的2种模式相对白菜连作模式,都显著增加了小被孢霉属(Mortierella)的丰度.进一步灌施分离来自大豆根瘤的8株根瘤菌,测定该8株根瘤菌对白菜根肿病的防效,结果显示8株根瘤菌的防治效果都高于45％,其中防治效果最好的是RG-4菌株,相对防效达到66.39％,表明大豆根瘤菌在大豆轮作中防治白菜根肿病起到重要作用.[结论]大豆/白菜轮作后显著降低了白菜根肿病的病情指数,对控制白菜根肿病具有良好的效果,该种植模式可作为防治白菜根肿病的重要栽培措施,在未来的农业生产中具有较好的应用推广前景.

Bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola (Xoc), impacts the production of rice. However, several rice cultivars displayed resistance to Xoc in the field, but scarce information is available about the role of endophytic microbiota in disease resistance. In the present study, the endophytic bacterial communities of resistant and susceptible rice cultivars "CG2" and "IR24", respectively, were analyzed using high throughput 16S rRNA gene amplified sequencing and culture dependent method was further used for bacterial isolation. A total of 452,716 high-quality sequences representing 132 distinct OTUs (Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes) and 46 isolates of 16 genera were explored from rice leaves infected with Xoc. Community diversity of endophytic bacteria were higher in the leaves of the resistant cultivars compared to susceptible cultivars upon Xoc infection. Strikingly, this diversity might contribute to natural defense of the resistant cultivar against pathogen. Pantoea, which is pathogen antagonist, was frequently detected in two cultivars and higher abundance were recorded in resistant cultivars. Different abundance genus includes endophytic isolates with marked antagonistic activity to Xoc. The increased proportions of antagonistic bacteria, may contribute to resistance of rice cultivar against Xoc and the Pantoea genus was recruited by Xoc infection play a key role in suppressing the development of BLS disease in rice. Taken together, this work reveals the association between endophytic bacteria and BLS resistance in rice and identification of antagonism-Xoc bacterial communities in rice.

玉米小斑病是玉米生产中的重要病害之一,本研究利用传统植物病理学和荧光定量PCR方法,研究抗生素溶杆菌对玉米小斑病菌(Bipolaris maydis)的生防效果和作用机制,为玉米小斑病的生物防控提供理论依据.结果显示,抗生素溶杆菌13-6对玉米小斑病菌丝生长和孢子萌发具有显著抑制作用,造成菌丝顶端生长受阻、表面粗糙,部分菌丝破裂,代谢粗提物抑制孢子萌发率高达92.19％,PI荧光染色显示病原菌孢子破裂并死亡.温室叶面喷施13-6发酵液、发酵液粗提物后显著降低玉米小斑病病情指数,相对防效分别达到42.43％和68.06％.诱导抗性实验表明:13-6对玉米小斑病的诱导防效达49.57％.玉米植株体内相关抗性基因表达结果显示,在灌根处理3 d后,抗病相关基因PR1和PR5、脂氧合酶LOX、乙烯受体ETR1均被激活表达,9 d达到最大值.研究证实抗生素溶杆菌13-6对玉米小斑病具有较好的生防效果,直接喷施可减缓玉米小斑病的发生,灌根施用使植株产生诱导抗性.

肠杆菌属(Enterobacter sp.)作为有益微生物的重要菌种,不仅对一些植物的生长起着促进作用,而且在有害生物防治方面起着重要的作用.本研究采用Biolog微生物生理生化分析、共培养等手段,对阴沟肠杆菌MY01、抗生素溶杆菌13-6与水稻细菌性条斑病菌RS105的营养和空间竞争能力、定殖特性以及对水稻幼苗的促生作用、条斑病的生防效果进行测定,明确阴沟肠杆菌与抗生素溶杆菌对水稻条斑病的协同生防作用.结果 显示MY01生长迅速且能利用大部分碳源,营养竞争能力较强,可限制其他细菌生长.温室喷雾接种时,MY01与13-6对水稻条斑病的防效相近,且MY01可增强13-6对水稻条斑病的相对防效,防效高达93.44％.阴沟肠杆菌MY01作为一种潜在的生防菌株,对水稻条斑病具有一定防效,且促进抗生素溶杆菌13-6对水稻条斑病的防治.

Bacterial leaf streak of rice (BLS), caused by Xanthomonas oryzae pv. oryzicola ( Xoc ), is an increasingly serious disease in southwestern China. This study aimed to evaluate the response of the native rice variety Hongyou-4 (HY4) to two different transcription activator -like effectors (TALEs) genotypes of Xoc . HY4 was significantly susceptible to Xoc strain 13T19 and resistant to Xoc strain YM15. Transcriptomic analysis of HY4 leaves in- oculated with the two Xoc TALEs genotypes revealed 1339 and 1219 differentially expressed genes (DEGs) in rice inoculated with Xoc strain 13T19 (HY.Q) and Xoc strain YM15 (HY.R), respectively, compared to the control. Quantitative real-time PCR (qRT-PCR) for expression of 10 randomly selected genes was used to verify the RNA-Seq data. Gene ontology (GO) analysis of the transcriptomic data showed DEGs of defense -related genes were predominantly assigned to 11 GO terms, with nine terms showing differential expression in HY4 after inoculation with the two Xoc genotypes. KEGG pathway clustering analysis revealed DEGs involved in plant - pathogen interactions and secondary metabolite pathways of phenylpropanoid biosynthesis were down -regu- lated in HY.Q compared to HY.R. Four transcription factors including bZIP, GLK, MADS, and MYB families, three resistance genes, and the TalAM2 effector target gene OsSWEET13, were differentially expressed in HY4 in- oculated with the two Xoc TALEs genotypes. These data clarify the mechanism of interactions between rice and different TALE genotypes of Xoc , and can help reveal disease -related metabolic pathways, molecular regulatory networks, and candidate genes involved in rice responses to TALEs of Xoc.

[目的]对大白菜生长素受体BrTIR1/AFBs基因家族进行系统分析,为大白菜BrTIR1/AFBs基因家族的功能挖掘和性状遗传改良提供理论依据.[方法]利用生物信息学方法,分析大白菜生长素受体基因家族的进化关系、编码蛋白、保守结构域和顺式作用元件.基于NCBI转录组测序(RNA-sep)数据,分析BrTIR1/AF-Bs基因家族在大白菜不同组织中的表达模式以及在根肿病入侵条件下的表达情况.[结果]从大白菜基因组数据库中鉴定得到10个BrTIR1/AFBs基因.拟南芥、茎瘤芥和大豆生长素受体基因家族多序列比对以及系统进化树分析结果显示:BrTIR1/AFBs基因分为6个亚家族(TIR1、AFB1、AFB2、AFB3、AFB4和AFB5),处于同一亚族的基因具有相似的结构.染色体定位结果显示:BrTIR1/AFBs基因家族成员分布在除Chr5、Chr6和Chr10号染色体之外的7条染色体上,呈现出不均匀分布.顺式作用元件分析结果显示:所有的BrTIR1/AF-Bs基因家族成员都含有响应生长素、防御和逆境胁迫的作用元件,预示着这些基因可能参与相应的生物学过程.组织表达模式分析发现:10个BrTIR1/AFBs基因的转录本在6个组织中被检测到,且不同组织中的表达量存在明显差异.大白菜BrTIR1/AFBs基因家族成员在根肿病病原菌入侵时表达量发生显著变化.[结论]大白菜生长素受体BrTIR1/AFBs基因家族成员具有保守的基因结构和功能结构域,在大白菜不同组织中发挥着特异的功能,且在抵御病害和干旱等逆境中发挥重要作用.