Isolation and Characterization of a Novel Jumbo Phage from Leaf Litter Compost and Its Suppressive Effect on Rice Seedling Rot Diseases

Abstract

Jumbo phages have DNA genomes larger than 200 kbp in large virions composed of an icosahedral head, tail, and other adsorption structures, and they are known to be abundant biological substances in nature. In this study, phages in leaf litter compost were screened for their potential to suppress rice seedling rot disease caused by the bacterium Burkholderia glumae, and a novel phage was identified in a filtrate-enriched suspension of leaf litter compost. The phage particles consisted of a rigid tailed icosahedral head and contained a DNA genome of 227,105 bp. The phage could lyse five strains of B. glumae and six strains of Burkholderia plantarii. The phage was named jumbo Burkholderia phage FLC6. Proteomic tree analysis revealed that phage FLC6 belongs to the same clade as two jumbo Ralstonia phages, namely RSF1 and RSL2, which are members of the genus Chiangmaivirus (family: Myoviridae; order: Caudovirales). Interestingly, FLC6 could also lyse two strains of Ralstonia pseudosolanacearum, the causal agent of bacterial wilt, suggesting that FLC6 has a broad host range that may make it especially advantageous as a bio-control agent for several bacterial diseases in economically important crops. The novel jumbo phage FLC6 may enable leaf litter compost to suppress several bacterial diseases and may itself be useful for controlling plant diseases in crop cultivation.

Annotated Sequence Record - Complete genomic sequences of two novel Ralstonia jumbo phages isolated from leaf litter compost

“…Among them, six jumbo Ralstonia phages: RSL1, RSF1, RSL2, RP12, RP31, and RsoM2USA, having genomic DNA >200 kbp are considered to have a broad host range [4][5][6][7][8]. Furthermore, it has been reported that three jumbo Burkholderia phages: FLC6, FLC8, and FLC9, isolated from leaf litter compost have the ability to lyse multiple isolates of R. pseudosolanacearum [9][10][11]. To establish practical jumbo phage-based biocontrol agents with lytic potential against a broad range of pathogenic Ralstonia spp.…”

Bacteriophages as Biotechnological Tools

“…The application of bacteriophages is not limited to medical use in animals and humans. In agriculture, they are used to treat different problems with bacterial contamination [ 68 , 69 , 70 ]. In the food industry, they are used as a microbiological control method for undesirable pathogens, increasing food safety [ 71 , 72 ].…”

A laudable strategy to manage bacterial panicle blight disease of rice using biocontrol agents

“…For BPB disease management, various bacterial genera, including Bacillus [11], Burkholderia [54], Pantoea [10], Pseudomonas [57], and Streptomyces [58,61] have been applied to the rice seeds. Instead of bacteria, bacteriophages also have used seed application to manage BPB disease [71,75]. However, the primary constraint of seed application is that seeds can only be integrated with a limited amount of BCA, which can be a limiting issue because a successful biological control activity might require a specific amount of BCA.…”

“…With rice, bacteriophages have been applied as BCA to control BPB pathogens under in vitro and glasshouse conditions. Under in vitro conditions, bacteriophages from leaf, namely FLC5 [70] and FLC6 [71] were examined genomically and showed potential application as BCAs to control B. glumae . In another related study, bacteriophages from rice seed extract, including bacteriophage Ф813, Ф843, and Ф173 showed antagonistic activity against B. glumae [74].…”