KHả NăNG Cố ĐịNH ĐạM CủA CHủNG VI KHUẩN AZOSPIRILLUM LIPOFERUM R29B1 Có KếT HợP CáC LIềU LƯợNG PHÂN ĐạM KHáC NHAU LÊN Sự SINH TRƯởNG Và NăNG SUấT TRÊN CÂY LúA TRONG ĐIềU KIệN NHà LƯớI

Để tăng trưởng, phát triển tốt và cho năng suất cao cây lúa cần nhiều chất dinh dưỡng nhưng quan trọng nhất là chất đạm. Việc sử dụng phân hóa học ở mức độ cao làm cho đất canh tác bạc màu và chai cứng. Thêm vào đó việc sử dụng phân bón dư thừa gây ô nhiễm môi trường ảnh hưởng đến sức khỏe của người tiêu dùng. Nhằm hạn chế vấn đề trên, đồng thời cùng với xu hướng tiến tới nền nông nghiệp sinh học bền vững, thí nghiệm này cần được thực hiện với mục đích xác định khả năng cố định đạm của dòng vi khuẩnAzospirillumlipoferumR29B1 nhằm đánh giá khả năng cải thiện sinh trưởng và phát triển của dòng vi khuẩn này trên cây lúa. Kết quả cho thấy việc chủng vi khuẩn và bón 50N cho các chỉ tiêu về thành phần năng suất khác biệt có ý nghĩa so với đối chứng và tương đương với nghiệm thức không chủng vi khuẩn bón 100N khi thực hiện thí nghiệm trong nhà lưới

Versatile role of Pseudomonas fuscovaginae cyclic lipopeptides in plant and microbial interactions

Pseudomonas fuscovaginae is the most prominent bacterial sheath rot pathogen, causing sheath brown rot disease in rice. This disease occurs worldwide and it is characterized by typical necrotic lesions on the sheath, as well as a reduction in the number of emitted panicles and filled grains. P. fuscovaginae has been shown to produce syringotoxin and fuscopeptin cyclic lipopeptides (CLPs), which have been linked to pathogenicity. In this study, we investigated the role of P. fuscovaginae UPB0736 CLPs in plant pathogenicity, antifungal activity and swarming motility. To do so, we sequenced the strain to obtain a single-contig genome and we constructed deletion mutants in the biosynthetic gene clusters responsible for the synthesis of CLPs. We show that UPB0736 produces a third CLP of 13 amino acids, now named asplenin, and we link this CLP with the swarming activity of the strain. We could then show that syringotoxin is particularly active against Rhizoctonia solani in vitro. By testing the mutants in planta we investigated the role of both fuscopeptin and syringotoxin in causing sheath rot lesions. We proved that the presence of these two CLPs considerably affected the number of emitted panicles, although their number was still significantly affected in the mutants deficient in both fuscopeptin and syringotoxin. These results reveal the importance of CLPs in P. fuscovaginae pathogenicity, but also suggest that other pathogenicity factors may be involved

Diversity of Bacillaceae on rice grown in acid sulfate soils in Vietnam : taxonomy, specialized metabolites, and inhibitory effects on fungal pathogens

Acid sulfate soils pose significant challenges to rice production due to their negative impact on root development and nutrient uptake, reducing rice yield and quality. The excessive use of fungicides by farmers to control rice diseases has exacerbated the issue as it contributes to environmental pollution and poses health risks. Our study aimed to isolate indigenous bacteria from rice grown in acid sulfate soils with potential biocontrol activity against common fungal pathogens in Vietnam. Using 16S rRNA amplicon sequencing, a total of ninety-one bacterial strains were identified up to the genus level. Bacillaceae were predominant on healthy rice plants, while Pseudomonas spp. also occurred on plants infested with the rice blast pathogen Pyricularia oryzae. Genome sequencing, protein orthology, and multilocus sequence analyses revealed the presence of six taxonomic groups of Bacillaceae: Rossellomorea marisflavi (basionym: Bacillus marisflavi), Priestia megaterium (basionym: Bacillus megaterium), Priestia koreensis (basionym: Bacillus koreensis), Bacillus thuringiensis, Bacillus altitudinis, and Bacillus siamensis. Dual-culture assays showed that most strains had antifungal activity against Pyricularia oryzae, Rhizoctonia solani AG2-1, and Bipolaris oryzae, while only B. siamensis and two B. thuringiensis strains were active against Rhizoctonia solani AG1-IA. R. marisflavi strains were in general inactive. Genome mining identified various biosynthetic gene clusters associated with specialized metabolite production, some of which were linked to potential antimicrobial activity. Production of these metabolites was confirmed by chemical analysis. These results suggest that indigenous Bacillaceae strains from acid sulfate soils could be used as biocontrol agents for the sustainable management of rice diseases under acidic conditions