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Zhao R, Su X, Yu F, Liu Z, Huang X. Identification and characterization of two closely related virga-like viruses latently infecting rubber trees ( Hevea brasiliensis). Front Microbiol 2023; 14:1286369. [PMID: 38156006 PMCID: PMC10752949 DOI: 10.3389/fmicb.2023.1286369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
A novel virga-like virus, provisionally named Rubber tree latent virus 2 (RTLV2), was identified from rubber tree (Hevea brasiliensis). It is a close relative of the previously reported Rubber tree latent virus 1 (RTLV1). The complete genomes of RTLV1 and RTLV2 were sequenced and comparatively analyzed in terms of genome organization, putative gene products and phylogenetic relationship. Both RTLV1 and RTLV2 have positive-sense single-stranded RNA genomes that encode seven open reading frames (ORFs), forming a similar genomic layout. In phylogenetic analyses based on replicase and coat protein amino acid sequences, RTLV1 and RTLV2 were clustered with unclassified virga-like viruses. They are distinct from currently recognized plant virus families. RTLV1 and RTLV2 can be distinguished from members of Virgaviridae by the presence of a putative coat protein duplex and a poly(A) tail at the 3'-terminus. The authenticity of RTLV1 and RTLV2 as infectious viruses was confirmed through field investigations and transmissibility assays. In conclusion, RTLV1 and RTLV2 represent a novel plant virus group that does not readily fit into current virus families.
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Affiliation(s)
- Ruibai Zhao
- College of Tropical Crops, Sanya Nanfan Research Institute of Hainan University, Sanya, China
- School of Life Sciences, Hainan University, Haikou, China
| | - Xiaoqi Su
- College of Tropical Crops, Sanya Nanfan Research Institute of Hainan University, Sanya, China
| | - Fengjuan Yu
- College of Tropical Crops, Sanya Nanfan Research Institute of Hainan University, Sanya, China
| | - Zhu Liu
- School of Life Sciences, Hainan University, Haikou, China
| | - Xi Huang
- College of Tropical Crops, Sanya Nanfan Research Institute of Hainan University, Sanya, China
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Zhou Q, Tu M, Fu X, Chen Y, Wang M, Fang Y, Yan Y, Cheng G, Zhang Y, Zhu Z, Yin K, Xiao Y, Zou L, Chen G. Antagonistic transcriptome profile reveals potential mechanisms of action on Xanthomonas oryzae pv. oryzicola by the cell-free supernatants of Bacillus velezensis 504, a versatile plant probiotic bacterium. Front Cell Infect Microbiol 2023; 13:1175446. [PMID: 37325518 PMCID: PMC10265122 DOI: 10.3389/fcimb.2023.1175446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/27/2023] [Indexed: 06/17/2023] Open
Abstract
Bacterial leaf streak (BLS) of rice is a severe disease caused by the bacterial pathogen Xanthomonas oryzae pv. oryzicola (Xoc) that has gradually become the fourth major disease on rice in some rice-growing regions in southern China. Previously, we isolated a Bacillus velezensis strain 504 that exhibited apparent antagonistic activity against the Xoc wild-type strain RS105, and found that B. velezensis 504 was a potential biocontrol agent for BLS. However, the underlying mechanisms of antagonism and biocontrol are not completely understood. Here we mine the genomic data of B. velezensis 504, and the comparative transcriptomic data of Xoc RS105 treated by the cell-free supernatants (CFSs) of B. velezensis 504 to define differentially expressed genes (DEGs). We show that B. velezensis 504 shares over 89% conserved genes with FZB42 and SQR9, two representative model strains of B. velezensis, but 504 is more closely related to FZB42 than SQR9, as well as B. velezensis 504 possesses the secondary metabolite gene clusters encoding the essential anti-Xoc agents difficidin and bacilysin. We conclude that approximately 77% of Xoc RS105 coding sequences are differentially expressed by the CFSs of B. velezensis 504, which significantly downregulates genes involved in signal transduction, oxidative phosphorylation, transmembrane transport, cell motility, cell division, DNA translation, and five physiological metabolisms, as well as depresses an additional set of virulence-associated genes encoding the type III secretion, type II secretion system, type VI secretion system, type IV pilus, lipopolysaccharides and exopolysaccharides. We also show that B. velezensis 504 is a potential biocontrol agent for bacterial blight of rice exhibiting relative control efficiencies over 70% on two susceptible cultivars, and can efficiently antagonize against some important plant pathogenic fungi including Colletotrichum siamense and C. australisinense that are thought to be the two dominant pathogenic species causing leaf anthracnose of rubber tree in Hainan province of China. B. velezensis 504 also harbors some characteristics of plant growth-promoting rhizobacterium such as secreting protease and siderophore, and stimulating plant growth. This study reveals the potential biocontrol mechanisms of B. velezensis against BLS, and also suggests that B. velezensis 504 is a versatile plant probiotic bacterium.
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Affiliation(s)
- Qi Zhou
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Min Tu
- Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Xue Fu
- Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
- College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Ying Chen
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Muyuan Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yuan Fang
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yichao Yan
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Guanyun Cheng
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yikun Zhang
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhongfeng Zhu
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Ke Yin
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Youlun Xiao
- Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Lifang Zou
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Gongyou Chen
- Shanghai Collaborative Innovation Center of Agri-Seeds/School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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