Background: Early leaf spot disease, caused by Cercospora arachidicola, is a devastating peanut disease that has severely impacted peanut production and quality. Chemical fungicides pollute the environment; however, Bacillus bacteria can be used as an environmentally friendly alternative to chemical fungicides. To understand the novel bacterial strain and unravel its molecular mechanism, De novo whole-genome sequencing emerges as a rapid and efficient omics approach. Results: In the current study, we identified an antagonistic strain, Bacillus amyloliquefaciens TA-1. In-vitro assay showed that the TA-1 strain was a strong antagonist against C. arachidicola, with an inhibition zone of 88.9 mm. In a greenhouse assay, results showed that the TA-1 strain had a significant biocontrol effect of 95% on peanut early leaf spot disease. De novo whole-genome sequencing analysis, shows that strain TA-1 has a single circular chromosome with 4172 protein-coding genes and a 45.91% guanine and cytosine (GC) content. Gene function was annotated using non-redundant proteins from the National Center for Biotechnology Information (NCBI), Swiss-Prot, the Kyoto Encyclopedia of Genes and Genomes (KEGG), clusters of orthologous groups of proteins, gene ontology, pathogen-host interactions, and carbohydrate-active enZYmes. antiSMASH analysis predicted that strain TA-1 can produce the secondary metabolites siderophore, tailcyclized peptide, myxochelin, bacillibactin, paenibactin, myxochelin, griseobactin, benarthin, tailcyclized, and samylocyclicin. Conclusion: The strain TA-1 had a significant biological control effect against peanut early leaf spot disease in-vitro and in greenhouse assays. Whole genome analysis revealed that, TA-1 strain belongs to B. amyloliquefaciens and could produce the antifungal secondary metabolites.

Grape downy mildew (GDM) is a destructive grapevine disease caused by Plasmopara viticola that occurs worldwide. In this study, we determined the characteristics of GDM epidemics and the grapevine canopy micro-climate in open-field, fungicide-spray, and rain-shelter plots during two constitutive years (2016 and 2017). It was found that rain shelter can significantly delay the disease occurrence by 28 and 21 days, reduce the epidemic phase by 28 and 21 days, and decrease the final disease index by 82% and 83%. Furthermore, it can block precipitation, reduce the relative humidity by 11% and 8%, and reduce the leaf wetness duration by 85% and 76% compared with open-field cultivation. A total of 3861, 783, and 1145 lesions were collected from the open-field, fungicide-managed, and rain-shelter plots, respectively, for analyses of the genetic diversity, population differentiation, and epidemic mode with seven microsatellite markers. In terms of genetic diversity, the Nei’s diversity index ranged from 0.569 to 0.680 and Shannon’s information index ranged from 0.958 to 1.226, showing high levels of diversity across populations. Similar to fungicide management, a rain shelter can significantly reduce the population’s genetic diversity. Low pairwise FST values (0.003–0.047) and high gene flow (Nm = 1.548–20.699) were observed among the three populations each year. In addition, most of the genetic variation occurred within populations. The epidemic mode of GDM in the open-field, fungicide-managed, and rain-shelter cultivation showed moderate, low, and high levels of clonality, respectively, in the case study.

This study investigated the impact of Aphis gossypii watery saliva on the induction of tomato (Solanum lycopersicum) plant resistance. To examine the role of A. gossypii saliva, we collected watery saliva from A. gossypii after a 48 h feeding period on an artificial diet. SDS-PAGE resolving gel 12% was used to separate the salivary proteins. Relative expression of gene analysis revealed that the intrusion of A. gossypii saliva dripping onto S. lycopersicum leaves triggered robust defense responses mediated by a signaling molecule, i.e., salicylic acid, while the signaling molecule’s jasmonic acid-dependent defense responses were moderately activated. Aphid saliva infiltrated S. lycopersicum leaves slowed the intrinsic rate of population growth of A. gossypii and significantly reduced the number of nymphs produced daily, compared to untreated leaves. During a choice test with untreated S. lycopersicum, aphids showed a repellent response towards saliva-infiltrated S. lycopersicum. Moreover, the (EPG) electrical penetration graph analysis demonstrated that the eating pattern of A. gossypii compared to untreated S. lycopersicum, that had been exposed to saliva was negatively impacted. These results provide compelling evidence for the involvement of salivary components of A. gossypii in inducing resistance against aphids in S. lycopersicum plants. Furthermore, the study underscores the crucial role of watery saliva in the intricate interactions between aphids and plants. The activation of pathways was also part of the defensive response (jasmonic acid (JA), salicylic acid (SA) signaling molecules). The findings of this research deliver valuable insights into the potential of watery aphid saliva as a natural defense mechanism against aphid infestations in S. lycopersicum crops.