Bactericidal Effect of Pseudomonas oryziphila sp. nov., a Novel Pseudomonas Species Against Xanthomonas oryzae Reduces Disease Severity of Bacterial Leaf Streak of Rice

Ruihuan Yang; Shengzhang Li; Yilang Li; Yichao Yan; Yuan Fang; Lifang Zou; Gongyou Chen

doi:10.3389/fmicb.2021.759536

Bactericidal Effect of Pseudomonas oryziphila sp. nov., a Novel Pseudomonas Species Against Xanthomonas oryzae Reduces Disease Severity of Bacterial Leaf Streak of Rice

Front Microbiol. 2021 Nov 4:12:759536. doi: 10.3389/fmicb.2021.759536. eCollection 2021.

Authors

Ruihuan Yang¹, Shengzhang Li¹, Yilang Li¹, Yichao Yan¹, Yuan Fang¹, Lifang Zou^{1

2}, Gongyou Chen^{1

2}

Affiliations

¹ School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.
² State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.

Abstract

Pseudomonas is a diverse genus of Gammaproteobacteria with increasing novel species exhibiting versatile trains including antimicrobial and insecticidal activity, as well as plant growth-promoting, which make them well suited as biocontrol agents of some pathogens. Here we isolated strain 1257 that exhibited strong antagonistic activity against two pathovars of Xanthomonas oryzae, especially X. oryzae pv. oryzicola (Xoc) responsible for the bacterial leaf streak (BLS) in rice. The phylogenetic, genomic, physiological, and biochemical characteristics support that strain 1257 is a representative of a novel Pseudomonas species that is most closely related to the entomopathogenic bacterium Pseudomonas entomophila. We propose to name it Pseudomonas oryziphila sp. nov. Comparative genomics analyses showed that P. oryziphila 1257 possesses most of the central metabolic genes of two closely related strains P. entomophila L48 and Pseudomonas mosselii CFML 90-83, as well as a set of genes encoding the type IV pilus system, suggesting its versatile metabolism and motility properties. Some features, such as insecticidal toxins, phosphate solubilization, indole-3-acetic acid, and phenylacetic acid degradation, were disclosed. Genome-wide random mutagenesis revealed that the non-ribosomal peptide catalyzed by LgrD may be a major active compound of P. oryziphila 1257 against Xoc RS105, as well as the critical role of the carbamoyl phosphate and the pentose phosphate pathway that control the biosynthesis of this target compound. Our findings demonstrate that 1257 could effectively inhibit the growth and migration of Xoc in rice tissue to prevent the BLS disease. To our knowledge, this is the first report of a novel Pseudomonas species that displays a strong antibacterial activity against Xoc. The results suggest that the P. oryziphila strain could be a promising biological control agent for BLS.

Keywords: Pseudomonas oryziphila; Xanthomonas oryzae; bacterial leaf streak of rice; bactericidal effect; biocontrol agents.