Search

Introduction: Several microorganisms in the plant root system, especially in the rhizosphere, have their own compositions and functions. Corm rot is the most severe disease of Crocus sativus, leading to more than 50% mortality in field production. Methods: In this study, metagenomic sequencing was used to analyze microbial composition and function in the rhizosphere of C. sativus for possible microbial antagonists against pathogenic Fusarium oxysporum. Results: The microbial diversity and composition were different in the C. sativus rhizosphere from different habitats. The diversity index (Simpson index) was significantly lower in the C. sativus rhizospheric soil from Chongming (Rs_CM) and degenerative C. sativus rhizospheric soil from Chongming (RsD_CM) than in others. Linear discriminant analysis effect size results showed that differences among habitats were mainly at the order (Burkholderiales, Micrococcales, and Hypocreales) and genus (Oidiodendron and Marssonina) levels. Correlation analysis of the relative lesion area of corm rot showed that Asanoa was the most negatively correlated bacterial genus (ρ = −0.7934, p < 0.001), whereas Moniliophthora was the most negatively correlated fungal genus (ρ = −0.7047, p < 0.001). The relative lesion area result showed that C. sativus from Qiaocheng had the highest resistance, followed by Xiuzhou and Jiande. C. sativus groups with high disease resistance had abundant pathogen resistance genes, such as chitinase and β-1,3-glucanase genes, from rhizosphere microorganisms. Further, 13 bacteria and 19 fungi were isolated from C. sativus rhizosphere soils, and antagonistic activity against pathogenic F. oxysporum was observed on potato dextrose agar medium. In vivo corm experiments confirmed that Trichoderma yunnanense SR38, Talaromyces sp. SR55, Burkholderia gladioli SR379, and Enterobacter sp. SR343 displayed biocontrol activity against corm rot disease, with biocontrol efficiency of 20.26%, 31.37%, 39.22%, and 14.38%, respectively. Discussion: This study uncovers the differences in the microbial community of rhizosphere soil of C. sativus with different corm rot disease resistance and reveals the role of four rhizospheric microorganisms in providing the host C. sativus with resistance against corm rot. The obtained biocontrol microorganisms can also be used for application research and field management. [ABSTRACT FROM AUTHOR]

Many studies on plant biostimulants and organic fertilizers have been focused on the ability of these products to increase crop productivity and ameliorate crop tolerance to abiotic stresses. However, little information is available on their effect on plant microbiota, whereas it is well known that microorganisms associated with plant play crucial roles on the health and productivity of their host. The aim of this study was to evaluate the effect of a vegetal-derived protein hydrolysate (PH), a vegetal-derived PH enriched with copper (Cu-PH), and a tropical plant extract enriched with micronutrients (PE) on shoot growth and the epiphytic bacterial population of lettuce plants and the ability of these products to enhance the growth of beneficial or harmful bacteria. The three plant-derived products enhanced shoot biomass of lettuce plants indicating a biostimulant effect of the products. Data obtained using culture-independent (Terminal Restriction Fragment Length Polymorphism and Next Generation Sequencing) and culture-dependent approaches indicated that foliar application of commercial products altered the composition of the microbial population and stimulated the growth of specific bacteria belonging to Pantoea , Pseudomonas , Acinetobacter , and Bacillus genus. Data presented in this work demonstrated that some of these strains exhibited potential plant growth-promoting properties and/or biocontrol activity against fungi and bacteria phytopathogens including Fusarium , Trichoderma , and Erwinia species. No indication of potential health risks associated to the enrichment of human or plant bacterial pathogens emerged by the analysis of the microbiota of treated and no-treated plants. Overall, the findings presented in this study indicate that the commercial organic-based products can enhance the growth of beneficial bacteria occurring in the plant microbiota and signals produced by these bacteria can act synergistically with the organic compounds to enhance plant growth and productivity. [ABSTRACT FROM AUTHOR]

Introduction: Several microorganisms in the plant root system, especially in the rhizosphere, have their own compositions and functions. Corm rot is the most severe disease of Crocus sativus , leading to more than 50% mortality in field production., Methods: In this study, metagenomic sequencing was used to analyze microbial composition and function in the rhizosphere of C. sativus for possible microbial antagonists against pathogenic Fusarium oxysporum ., Results: The microbial diversity and composition were different in the C. sativus rhizosphere from different habitats. The diversity index (Simpson index) was significantly lower in the C. sativus rhizospheric soil from Chongming (Rs&#95;CM) and degenerative C. sativus rhizospheric soil from Chongming (RsD&#95;CM) than in others. Linear discriminant analysis effect size results showed that differences among habitats were mainly at the order (Burkholderiales, Micrococcales, and Hypocreales) and genus ( Oidiodendron and Marssonina ) levels. Correlation analysis of the relative lesion area of corm rot showed that Asanoa was the most negatively correlated bacterial genus (ρ = -0.7934, p < 0.001), whereas Moniliophthora was the most negatively correlated fungal genus (ρ = -0.7047, p < 0.001). The relative lesion area result showed that C. sativus from Qiaocheng had the highest resistance, followed by Xiuzhou and Jiande. C. sativus groups with high disease resistance had abundant pathogen resistance genes, such as chitinase and β-1,3-glucanase genes, from rhizosphere microorganisms. Further, 13 bacteria and 19 fungi were isolated from C. sativus rhizosphere soils, and antagonistic activity against pathogenic F . oxysporum was observed on potato dextrose agar medium. In vivo corm experiments confirmed that Trichoderma yunnanense SR38, Talaromyces sp. SR55, Burkholderia gladioli SR379, and Enterobacter sp. SR343 displayed biocontrol activity against corm rot disease, with biocontrol efficiency of 20.26%, 31.37%, 39.22%, and 14.38%, respectively., Discussion: This study uncovers the differences in the microbial community of rhizosphere soil of C. sativus with different corm rot disease resistance and reveals the role of four rhizospheric microorganisms in providing the host C. sativus with resistance against corm rot. The obtained biocontrol microorganisms can also be used for application research and field management., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhang, Lu, Zhu, Huang, Qin and Zhu.)