Date palm ((Phoenix doctylifera L.) suffers from several fungal diseases. The endophytic microorganisms present in higher plants generally offer protection to their host plants against invading phytopathogenic fungi and bacteria. In the present study, endophytic bacteria associated with date palm leaves were isolated and their in vitro antagonistic potential against fungal pathogens causing leaf spots in date palm was demonstrated. Endophytic bacteria were isolated from date palm leaves of 3 different cultivars viz., Nighal, Khalas and Khinaizi and evaluated for their inhibitory activity against leaf spot pathogens of date palm viz., Fusarium solani, Alternaria sp., Nigrospora sp., Thieloviopsis sp., Curvularia subpapendrofii and Tilletiopsis minor using an in vitro dual culture assay. Of the 24 endophytic bacterial strains tested, the endophytes designated B1, B7, B8 and B9 obtained from cv. Nighal showed inhibitory activities (more than 55% mycelial growth inhibition) against F. solani and Alternaria sp. None of the bacterial endophytes inhibited the growth of other fungal pathogens tested. These antagonistic bacterial strains were identified as Pantoea septica on the basis of 16S rRNA gene sequence analysis. The hyphae of F. solani and Alternaria sp. exhibited morphological abnormalities such as shrinkage and disintegration when grown in the presence of antagonistic bacterial endophytes. The cell-free culture filtrates of the bacterial endophytes caused inhibition of mycelial growth and induced leakage of electrolytes from the mycelia of F. solani and Alternaria sp. This is the first study that describes inhibition of the date palm pathogens F. solani and Alternaria sp. by P. septica. Endophytic Pantoea septica strains isolated from date palm leaves inhibited the mycelial growth of F. solani and Alternaria sp. and induced morphological changes in their mycelia. The culture filtrates of these bacterial strains also inhibited the mycelial growth and caused leakage of electrolytes from the mycelia of F. solani and Alternaria sp. These promising bacterial strains can be exploited as biocontrol agents to control F. solani and Alternaria sp.-induced leaf spot diseases of date palm.

中文翻译：

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从椰枣（Phoenix doctylifera L.）中分离出的内生细菌对引起椰枣叶斑病的真菌病原菌的体外抗真菌活性

从cv获得的命名为B1，B7，B8和B9的内生菌。Nighal对F. solani和Alternaria sp。表现出抑制作用（超过55％的菌丝生长抑制作用）。没有一种细菌内生菌能抑制其他真菌病原体的生长。根据16S rRNA基因序列分析，将这些拮抗细菌菌株鉴定为败血性泛菌。F. solani和链格孢菌的菌丝。在拮抗细菌内生菌的存在下生长时，表现出形态异常，例如收缩和崩解。细菌内生菌的无细胞培养物滤液抑制了菌丝体的生长，并引起了茄形镰刀菌和链格孢菌菌丝体中电解质的泄漏。这是第一个描述了对枣椰子病原菌F. solani和Alternaria sp。的抑制作用的研究。由败血性疟原虫。从枣棕榈叶分离的内生泛脓杆菌菌株抑制茄镰刀菌和链格孢菌的菌丝生长。并引起菌丝体形态变化。这些细菌菌株的培养滤液也抑制了菌丝体的生长，并引起了茄形镰刀菌和链格孢菌的菌丝体中电解质的泄漏。这些有前途的细菌菌株可以用作生物防治剂，以控制茄形镰刀菌和链格孢菌引起的枣椰子叶斑病。solani和Alternaria sp。这些有前途的细菌菌株可以用作生物防治剂，以控制茄形镰刀菌和链格孢菌引起的枣椰子叶斑病。solani和Alternaria sp。这些有前途的细菌菌株可以用作生物防治剂，以控制茄形镰刀菌和链格孢菌引起的枣椰子叶斑病。