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BACKGROUND: The continuous cropping of peanuts is a primary cause of yield and quality loss. Solutions to this problem should be therefore developed to ensure the sustainability of peanut production. RESULTS: In this study, colonization by the endophytic fungus Phomopsis liquidambari was detected, which led to significantly improved rhizosphere soil microenvironment, enhanced N, P and K assimilation and suppressed incidence of peanut disease. Statistical analysis demonstrated that the yield enhancement was significantly correlated with improvement of the rhizosphere soil microenvironment and the peanut's physiological status by P. liquidambari colonization. In addition, P. liquidambari colonization also significantly improved peanut quality. CONCLUSION: Our results indicate that the practical application of the endophytic fungus P. liquidambari has a strong potential to alleviate the obstacles associated with continuous peanut cropping under field conditions. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background and aims: Fungal endophyte Phomopsis liquidambari B3 effectively increases nodule number and productivity of peanut when grown in a monoculturing system, but the underlying mechanisms are not well understood. Plant physiological status is the key mechanism that determines the legume-rhizobium interaction under stressful conditions. Therefore, this research aimed to study the physiological mechanisms behind the P. liquidambari-mediated monoculturing peanut nodulation enhancement. Methods: Peanut-rhizobia symbiosis, plant defense enzyme activity in shoots and roots, photosynthetic activity and soluble sugar content in leaves, as well as the carbon metabolism-related enzyme activity and carbon metabolites content in nodules were measured after live P. liquidambari and P. liquidambari fragments treatment under continuous monoculturing condition. Results: P. liquidambari instead of its fragments significantly enhanced nodule initiation, nodule development and nodule N-fixation efficiency. Plants treated with live P. liquidambari showed higher leaf photosynthetic activity, soluble sugar accumulation, nodule carbohydrate catabolism activity and seed yield, whereas plant defense response was similar in endophyte and endophyte fragments treated plants. Conclusion: Our results demonstrated that the improved efficiency of symbiosis in peanut continuous monoculturing system, induced by P. liquidambari, was likely linked to the improved plant aboveground nutritional status rather than to the induction of plant defense. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted to investigate the effects of applying endophytic fungi Phomopsis liquidambari strain B3, Phomopsis sp. strain NJ4. 1, and Ceratobasidum stevensii strain B6 on the soil biological characteristics and enzyme activities under continuously cropped peanut at its different growth stages. Compared with the control, applying B3 increased the peanut yield significantly by 19. 8%, and applying NJ4. 1, B3 and B6 increased the peanut nodule number significantly by 20. 4%, 29. 3% and 27. 6%, respectively. In the three treatments of applying endophytic fungi, the average population of soil bacteria and actinomycetes in the whole growth period of peanut was higher than that of the control, and the soil microbial biomass carbon was significantly greater at germination and seedling stages. The soil microbial biomass nitrogen increased at germination stage, but decreased at flowering stage. The DGGE analysis indicated that at flowering stage, the soil bacteria and fungi in treatment B3 had the largest band number and diversity. From germination stage to maturing stage, the three treatments of applying endophytic fungi had higher activities of soil invertase and catalase than the control, but less difference in soil urease activity. It was suggested that applying endophytic fungi could improve the peanut continuous cropping soil environment, and applying B3 had the best effect. [ABSTRACT FROM AUTHOR]

In peanut continuous cropping soil, the application of fungal endophyte Phomopsis liquidambari B3 showed peanut pod yield promotion and root nodule number increase. P. liquidambari improved soil environment by degrading allelochemicals and thus promoted peanut pod yield. Furthermore, peanut yield promotion is in part due to the root nodule increase since nodular nitrogen fixation provides the largest source of nitrogen for peanut. However, it is unknown whether this nodule number increase is induced by fungal endophyte. We therefore conducted several pot experiments using vermiculite to investigate the effects of P. liquidambari on peanut-bradyrhizobium nodulation. Our results showed that P. liquidambari co-inoculated with bradyrhizobium increased root nodule number and shoot accumulated nitrogen by 28.25% and 29.71%, respectively. Nodulation dynamics analysis showed that P. liquidambari accelerated nodule initiation and subsequent nodule development. Meanwhile, P. liquidambari was able to colonize the peanut root as an endophyte. The dynamics of P. liquidambari and bradyrhizobial root colonization analysis showed that P. liquidambari inoculation significantly increased the rate of bradyrhizobial colonization. Furthermore, P. liquidambari inoculation significantly increased flavonoids synthesis-related enzymes activities, two common types of flavonoid (luteolin and quercetin-peanut rhizobial nod gene inducer) secretion and lateral root (peanut rhizobial infection site) formation, indicating that P. liquidambari altered the peanut nodulation-related physiological and metabolic activities. These obtained results confirmed the direct contribution of P. liquidambari in enhancing peanut-bradyrhizobium interaction, nodulation and yield. [ABSTRACT FROM AUTHOR]

The recently isolated fungal strain Phomopsis liquidambari B3 can degrade high concentrations of indole, indicating its potential for the bioremediation of indole-contaminated soil. In this study, a specific real-time PCR was developed to detect the survival of P. liquidambari B3 in soil. Subsequently, degradation activity of strain B3 and its effects on indigenous microbial community were analyzed. Results showed the amount of P. liquidambari B3 genomic DNA increased to a maximum 5.67 log (pg g −1 dry soil) 10 days after inoculation of 5.04 log (pg g −1 dry soil), and then gradually decreased with time and after 40 days it was below the detection limit. By the end of the experiment (day 40), bioaugmented microsoms showed a 93.7% decrease in indole, while the values for biostimulated and control microcosms were much lower. Higher microbial biomass and enzyme activities were observed in bioaugmented soil. Denaturing gradient gel electrophoresis analysis showed bioaugmentation increased richness of resident microbial community. These results indicate that P. liquidambari B3 is effective for the remediation of indole-contaminated soil and also provides valuable information about the behavior of the inoculant population during bioremediation, which could be directly used in the risk assessment of inoculant population and optimization of bioremediation process. [ABSTRACT FROM AUTHOR]