Department of Botany, Abdul Wali Khan University, Mardan, Pakistan.
Department of Botany, Abdul Wali Khan University, Mardan, Pakistan.
Microb Pathog. 2024 Dec;197:107084. doi: 10.1016/j.micpath.2024.107084. Epub 2024 Oct 25.
Rice production is highly susceptible to various pathogens, including Rhizoctonia solani, Curvularia lunata, and Epicoccum rostratum, which are major threats in Asia. Exploring biological control methods using endophytic bacteria offers promising opportunities to enhance rice resilience against these lethal diseases. Using 16S RNA sequencing, we identified four endophytic isolates of Bacillus spp. from rice roots, stems, and leaves. We evaluated the antagonistic activity of these endophytic bacterial isolates against rice pathogens both in vitro and in vivo. These isolates inhibited the growth of C. lunata by 82 %, R. solani by 79 %, and E. rostratum by 88 % in vitro. The detached leaf assay for sheath blight (ShB) disease severity in strains ranged from 10.4 % to 73.3 %. In vivo results showed that B. amyloliquefaciens (R-19) exhibited the lowest disease intensity at 7.2 % and the highest disease suppression at 78.8 %. The fungicide propiconazole at 0.1 % treatment showed the lowest disease intensity of 7.7 % and the highest disease suppression of 73.4 %, compared to the infected control. Besides biocontrol efficacy, endophytic isolates enhance plant growth parameters, including shoot height, root length, fresh and dry weights, number of tillers, and grains per tiller. Plant hormones abscisic acid (ABA) and gibberellic acids (GA) increased by 35 % and 53 %, respectively, due to B. subtilis (R-20) and B. amyloliquefaciens (R-19), while flavonoid and indole acetic acid (IAA) concentrations surged by 30%-80 %. Similarly, chlorophyll (a, b), carotenoids, antioxidant enzymatic activity, phenolic content, carbohydrates, and proline contents were higher compared to the control. This study provides a foundation for future studies on novel and eco-friendly biocontrol agents. In addition, our study recommends the integration of endophytic bacteria into sustainable agriculture for enhancing rice production and reducing disease impacts.
水稻生产极易受到各种病原体的影响，包括立枯丝核菌、旋孢腔菌和罗司氏层出菌，这些病原体是亚洲地区的主要威胁。利用内生细菌探索生物防治方法为提高水稻对这些致命疾病的抗性提供了有前景的机会。我们使用 16S RNA 测序技术，从水稻的根、茎和叶中鉴定出四种内生芽孢杆菌属的内生菌。我们评估了这些内生细菌分离物在体外和体内对水稻病原体的拮抗活性。这些分离物在体外对旋孢腔菌的抑制率为 82%，对立枯丝核菌的抑制率为 79%，对罗司氏层出菌的抑制率为 88%。在叶片离体接种稻瘟病（ShB）的严重程度测试中，菌株的范围为 10.4%至 73.3%。体内结果表明，解淀粉芽孢杆菌（R-19）的病情指数最低，为 7.2%，病情抑制率最高，为 78.8%。与感染对照相比，0.1%的杀菌剂丙环唑处理的病情指数最低，为 7.7%，病情抑制率最高，为 73.4%。除了生物防治效果外，内生分离物还能提高植物生长参数，包括株高、根长、鲜重和干重、分蘖数和每分蘖的粒数。由于解淀粉芽孢杆菌（R-20）和枯草芽孢杆菌（R-19）的作用，植物激素脱落酸（ABA）和赤霉素（GA）分别增加了 35%和 53%，而类黄酮和吲哚乙酸（IAA）的浓度则增加了 30%-80%。同样，与对照相比，叶绿素（a、b）、类胡萝卜素、抗氧化酶活性、酚类物质含量、碳水化合物和脯氨酸含量也更高。本研究为新型和环保型生物防治剂的未来研究提供了基础。此外，我们的研究建议将内生细菌整合到可持续农业中，以提高水稻产量并降低疾病的影响。
