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Aims: In this study, the control effects of synthetic microbial communities composed of peanut seed bacteria against seed aflatoxin contamination caused by Aspergillus flavus and root rot by Fusarium oxysporum were evaluated., Methods and Results: Potentially conserved microbial synthetic communities (C), growth-promoting synthetic communities (S), and combined synthetic communities (CS) of peanut seeds were constructed after 16S rRNA Illumina sequencing, strain isolation, and measurement of plant growth promotion indicators. Three synthetic communities showed resistance to root rot and CS had the best effect after inoculating into peanut seedlings. This was achieved by increased defense enzyme activity and activated salicylic acid (SA)-related, systematically induced resistance in peanuts. In addition, CS also inhibited the reproduction of A. flavus on peanut seeds and the production of aflatoxin. These effects are related to bacterial degradation of toxins and destruction of mycelia., Conclusions: Inoculation with a synthetic community composed of seed bacteria can help host peanuts resist the invasion of seeds by A. flavus and seedlings by F. oxysporum and promote the growth of peanut seedlings., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)

Aims: This study evaluated the control effect of the endophytic fungus Phomopsis liquidambaris B3 against rice bakanae disease (RBD) caused by Fusarium proliferatum and the disease control result of different inoculation times of beneficial micro-organisms., Methods and Results: Rice seedlings preinoculated, coinoculated and noninoculated with B3 were exposed to F. proliferatum stress and grown under controlled conditions. Greenhouse experimental results showed that rice preinoculation with B3 significantly reduced rice bakanae disease by 21.45%, inhibited the colonization of F. proliferatum, increased defence-related enzyme activities, upregulated the expression of defence genes and promoted plant photosynthesis. However, bakanae disease in rice coinoculation with B3 increased by 11.45%, resulted in excessive reactive oxygen species (ROS) bursts and plant cell death., Conclusions: Preinoculation with the endophytic fungus P. liquidambaris B3 significantly reduced rice bakanae disease by triggering the SA-dependent defence pathways of plants, and promoted plant growth. However, coinoculatiton with P. liquidambaris B3 activated excessive defence responses, resulting in plants cell death and aggravation of bakanae disease., Significance and Impact of the Study: This study indicated that P. liquidambaris B3 was an effective method for agricultural control against rice bakanae disease caused by F. proliferatum, and provides an experimental basis for the development of sustainable endophytic fungal resources to effectively control plant diseases caused by pathogenic fungi, and suggests that precise application of beneficial micro-organisms may be become a key factor in farmland crop disease management., (© 2022 Society for Applied Microbiology.)

Aims: To explore if and how symbiotic Phomopsis liquidambari-rice system influences below-ground straw decomposition and then nitrogen(N) transformation in response to environmental N levels., Methods and Results: Litter bag experiments were utilized to trace the decay process during rice growth phases (seedling (T1), tillering (T2), heading (T3) and maturing (T4) stage), with (E+) and without endophyte (E-), under low (LN), medium (MN) and high nitrogen (HN) supply. Litter, soil and plant samples were collected to evaluate the decay process, N transformations, plant quality and relative abundance of soil ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and P. liquidambari. The results showed that straw decomposition increased by 19·76% (LN, T2 stage), 14·05% (MN, T3 stage) and 16·88% (MN, T4 stage) in E+ pots when compared with E- pots. Further analysis revealed that no significant endophyte × N interaction was found for straw decay rate and that the decay rate was reduced by a higher N supply (LN, 37·16 ± 0·65%; MN, 32·27 ± 1·72%; HN, 29·44 ± 1·22%) at the T1 stage, whereas straw decay rate and N release increased by 9·38 and 11·16%, respectively, mainly by endophyte colonization at the T4 stage. The abundance of AOA and AOB were altered, corresponding with the decay rate. Soil mineral N, straw mineral N and plant quality were shown to increase in E+ pots, depending on environmental N conditions and growth phase. The yield increased by 2·98% for E+ plants under MN level., Conclusions: Symbiotic P. liquidambari-rice system promoted below-ground straw decomposition and N transformation, depending on environmental N levels and plant growth phase., Significance and Impact of the Study: This study provides evidence that fungal endophyte-plant systems are able to promote N transformation by increasing straw decomposition. A reasonable combination of N inputs could enhance its advantage in agriculture ecosystems., (© 2018 The Society for Applied Microbiology.)

Aims: Plants, fungal endophytes (FEs) and the changing environment interact with each other forming an interlaced network. This study evaluates nonadditive and interactive effects of the FE Acremonium strictum and drought treatment on Atractylodes lancea plantlets., Methods and Results: By applying FEs (meristem cultures of At. lancea, fungal inoculation of Ac. strictum and plantlet acclimatization) and drought treatment (regular watering, mild drought, severe drought), a research system of At. lancea ramets under different treatments was established. During 12 days of drought treatment, the plantlets' physiological responses and basic growth traits were measured and analysed. Although drought and FE presence affected plantlet traits to differing degrees, the interactive effects of the two were more pronounced. In particular under mild drought treatment, the FE conferred drought tolerance to plantlets by enhancing leaf soluble sugars, proteins, proline and antioxidant enzyme activity; decreasing the degree of plasmalemma oxidation; and increasing the host's abscisic acid level and root:shoot ratio. When exposed to regular watering or severe drought, these effects were not significant., Conclusions: Plant traits plasticity was conferred by dual effects of drought stress and FEs, and these factors are interactive. Although FEs can help plants cope with drought stress, the beneficial effects are strictly constrained by drought degree., Significance and Impact of the Study: During finite environmental stress, FEs can benefit plants, and for this reason, they may alleviate the effects of climate change on plants. However, because the benefits of FEs are highly context dependent, the role of FEs in a changing background should be re-assessed., (© 2014 The Society for Applied Microbiology.)

Aims: To explore specific mechanisms of endophytic Pseudomonas fluorescens antagonizing Athelia rolfsii, causing southern blight of Atractylodes lancea and to evaluate the potential of this Ps. fluorescens strain to control southern blight., Methods and Results: Endophytic Ps. fluorescens strain ALEB 7B isolated from A. lancea can significantly inhibit the growth of A. rolfsii strain SY4. Pre-inoculating A. lancea seedlings with Ps. fluorescens ALEB 7B reduces the southern blight morbidity rate significantly. In situ observation using scanning electron microscopy shows Ps. fluorescens ALEB 7B colonizing the plant cells. Volatile organic compounds (VOCs) from Ps. fluorescens ALEB 7B can kill A. rolfsii SY4 and dimethyl disulphide (DMDS) plays a major role. 2-Piperidinone is a unique substance having antifungal activity in dichloromethane extracts of bacterial cell-free culture filtrates. Other antagonistic mechanisms include ecological niche occupation, antibiotic production and lytic exoenzymes secretion., Conclusions: Specific antagonistic mechanisms of Ps. fluorescens ALEB 7B on A. rolfsii SY4 were detailed, including release of DMDS, production of 2-piperidone, secretion of antibiotics and lytic exoenzymes and competition for spaces and nutrients., Significance and Impact of the Study: This work firstly reports the significant inhibition of VOCs released by Ps. fluorescens on the growth of A. rolfsii. 2-Piperidinone is firstly found synthesized by Ps. fluorescens, having antifungal activity. This work provides an antagonistic bacterium with practical convenience and ecologically amity, which has potential for control to A. rolfsii in vitro., (© 2014 The Society for Applied Microbiology.)