Sharp eyespot (Rhizoctonia cerealis) is a widespread soil-borne fungal disease that poses a severe threat to wheat health, and it is one of the main obstacles to achieving stable and high-quality wheat yields in China. Our collaborative team has developed a novel, efficient, and low-toxicity fungicide named Y17991 (N-(2-(2,4-bis-(trifluoromethyl)phenoxy)phenyl)-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide). Preliminary laboratory tests confirmed the significant inhibitory effect of this agent on R. cerealis. Large-area field trials also demonstrated its efficacy, with a disease prevention index of 83.52%, which is 1.97% greater than that of the widely used thifluzamide, and it significantly increased the wheat yield. Moreover, this study explored the impacts of Y17991 on the structure and function of the microbial community in wheat rhizosphere soil. Bacterial communities were more strongly affected than fungal communities. Y17991 significantly modulated key amino acid metabolic pathways and certain biosynthetic processes in diseased wheat rhizospheres, and it also enhanced certain biosynthetic pathways and metabolic activities in healthy wheat rhizospheres. Additionally, the application of Y17991 regulated rhizosphere metabolites, thus exerting significant control over the microbial community. We identified 15 microbial strains potentially involved in the prevention and treatment of R. cerealis, and Y17991 treatment promoted the growth of Pedobacter and Bacillus strains. These strains not only aid in plant growth but they also have the potential for disease prevention. In summary, Y17991 application at a reasonable dose does not cause significant disruption to nontarget rhizosphere microbial communities. In future studies, we will continue to investigate the impacts of Y17991 on nonmicrobial components in soil ecosystems, such as protozoa and nematodes. Our research provides a theoretical basis for the scientific application and promotion of new fungicides and offers a significant reference for establishing a comprehensive system for assessing the ecological impact of pesticides on the environment.

Salinity is a major environmental stress affecting crop growth and productivity globally. The application of halo-tolerant plant growth-promoting bacteria (HT-PGPB) has been widely recognized to promote crop growth and reduce the adverse effects of salt stress. In this study, key endophytic bacteria that can respond to salinity changes were identified by analyzing the microbial community in propagules of Kandelia obovata. Delftia tsuruhatensis DYX29, a strain that can grow normally under high salinity conditions with a sodium chloride (NaCl) concentration of 5% (w/v), was obtained by pure culture. DYX29 can produce siderophores with a siderophore unit value of 87.6% and 1-aminocyclopropane-1-carboxylate (ACC) deaminase with 29 U L^–1, and its synthesis of intracellular amino acids and auxin can be induced by high salinity. Inoculation with DYX29 can remarkably promote the salt tolerance of rice. Under salt stress, the addition of DYX29 was shown to effectively promote the growth of rice seedlings through a variety of approaches. It increased the biomass of rice seedlings by 32.9% (dry weight) and promoted the accumulation of soluble sugars by 23.1%. It also increased catalase (CAT) and peroxidase (POD) activities in rice leaves by 37.8 and 88.2%, respectively. Moreover, it maintained the ionic homeostasis in rice roots and leaves. In addition, it upregulated the expression of growth-promoting hormones, such as indole-3-acetic acid (IAA), brassinolide (BL), abscisic acid (ABA), and salicylic acid (SA), in rice roots by 27.8, 69.5, 123.7 and 28.6%, respectively. This study provides inspiration for screening valuable salt-tolerant pro-biotic bacteria from mangrove ecosystems and their use for crop growth promotion under salt stress. It can also provide useful references for the development of new salt-tolerant and pro-biotic biofertilizers, as well as the investigation of the related mechanisms.