Genetic Diversity Of The Major Capsid Genes (g23) Of T4-type Bacteriophages In Uplands Black Soils And Paddy Fields In Northeast China

Bacteriophages (phages) are the most abundant biological entities in thebiosphere and play important roles in regulating the succession of host communities,biological evolution and biogeochemical cycling. Recently, the genetic diversities ofbacterial and fungal communities and their relationship with the inhabitedenvironments were intensively studied with the development of molecular biologicaltechniques. However, the diversity of bacteriophages is still little known. In this paper,the partial gene of g23, which encodes the major capsid protein of T4-type phageswas PCR amplified with degenerate primers MZIA1bis and MZIA6in DNA extractsfrom paddy field soils/water and upland soils in northeast China, and the geneticdiversity and community composition of T4-type phages were investigated. Theresults as followed:For upland black soils, totally99different g23clones were obtained from sixlocations in upland black soils in board range in northeast China. Approximately halfof the clones fell into paddy groups, whereas the rest belonged to one of severalgroups containing only clones from upland black soils or remained ungrouped,suggesting that the T4-type phage communities in the upland black soil wererelatively similar to those in paddy field soils but that specific communitiesexclusively inhabit the upland black soil. UniFrac analysis of all of the g23clonesobtained from various environments indicated that the T4-type phages communitiesvaried among marine, lake, paddy field soil and upland soil environments and theT4-type phage communities in upland black soils also varied with sampling locations.For paddy fiels soils, the g23in five paddy field soils during rice growth seasonwere analyzed, and106different g23clones were obtained, of which88clones weregrouped into redefined Paddy Groups â… ,â…¢,â…¤,â…¥,â…¦,â…§ and â…¨, and theremaining18clones were left ungrouped, suggesting that the high diversity of g23clones observed in paddy field soils in northeast China. Although the distributions ofg23in NE China were similar with those in paddy field soils in Japan, the T4-typephages communities as estimated by UniFrac were significant differences betweentwo counties.For paddy floodwaters, totally104different g23clones were obtained. Amongthem,78%clones showed the highest identities on the average of82%with the clonesretrieved from upland black soils and paddy field soils in northeast China, whereas the remaining sequences had the highest identities to those clones obtained in paddy fieldsoils in Japan and Lake origins, suggesting that g23genes in paddy floodwater wereclose to those in similar environmental conditions. In addition, UniFrac analysisresults showed that T4-type phage in paddy floodwater were shifted with samplinglocations and sampling time and clearly different with those in paddy field soils.By using exchange of ecological niches, soil convertion experiment with paddyfield soils and upland soils, and g23in the rhizosphere soils of rice and soybean andnon-rhizosphere soils were conduct. In total,160different g23clones were obtainedduring two growth stages. Blast search results showed that80.64%clones had thehigh the highest identities from57to100%with the clones retrieved from uplandblack soils and paddy field soils in NE China. UniFrac analysis results indicated thatT4-type phages communities had no rhizosphere effects, and also were not influencedby sampling times. T4-type phages community composition was mainly determinedby soil types, and then by crops.In conclusion, this study elucidated the diversity and community of T4-typephages by analysis of partial g23sequences obtained from upland black soils andpaddy fields in northeast China. The results showed that the highest diversity of g23of T4-type phages clones observed in both upland black soils and paddy fields innortheast China, and the g23clone assemableges which represented as of T4-typephage communities varied by sampling locations and sampling times. UniFracanalysis of the g23clone assemblages from different environments demonstrated thatT4-type phage communities were significant difference among marine, lake, paddyfield and unpland black soils, and in terrestrial environments the T4-type phagecommunities are determined both by biogeographic and ecological processes. Inaddition, the paddy field soils and upland soils convertion experiments showed thatT4-type phage community was first determined by soil types and second by crops.The results of this study will contribute to the development of viral ecology interrestrial enviroments.