Effects of Ozone Pollution and Ethylenediurea Spraying on the Rhizospheric Bacterial Community of Wheat Plant
[Objtctive]Tropospheric ozone(O3)is one of the most severe plant toxic air pollutants,it poses a serious threat to food production and security.Ethylenediurea(EDU)can effectively mitigate O3-induced crop yield loss.However the effects of elevated O3,EDU,and their interaction on the rhizospheric bacterial community of wheat plant remains unclear.[Method]Triticum aestivum L.Nongmai88 was grown in China O3 Free-Air Concentration Enrichment(O3-FACE)platform under either ambient atmospheric O3(A treatment)or 1.5 times ambient atmospheric O3(E treatment),and the foliage sprayed with 450 mg·L-1 EDU or equal mount of water every ten days.The rhizospheric bacterial communitites under different treatments were analyzed by MiSeq sequencing of bacterial 16S rRNA genes in combination with redundancy analysis(RDA).[Result]It was found that EDU increased wheat root biomass by 8%-58%and decreased soil pH by 4%-10%,both of which reached significant levels under A treatment.The elevated O3,EDU foliar spray,and their interaction did not significantly affect the alpha diversity indices of rhizospheric bacterial communities,but the elevated O3 caused significant variation in the whole bacterial community structure.In addition,the effect of EDU on the structure of the bacterial community in A treatment was more significant than that under E treatment.Proteobacteria(with a relative abundance ratio of 28%-39%),Bacteroidota(11%-20%),and Acidobacteriota(7%-11%)were the most dominant phyla in all treatments of the rhizosphere soil.Both the elevated O3 and EDU foliar spray significantly reduced the relative abundance of Alphaproteobacteria but increased the relative abundance of Chloroflexi.E treatment increased the relative abundance of Nitrospirota by 71%to 164%,while EDU treatment increased the relative abundance of Planctomycota by 23%to 70%.Based on the results of RDA,it was found that the content of available postassium(AK)and pH were the main drivers,explaining 21%and 16%of the variation in bacterial community structure,respectively(P<0.005).Furthermore,the Spearman correlation analysis results showed that the content of AK in rhizospheric soil was significantly negatively correlated with the relative abundance of the Chloroflexi and Nitrospirota phyla(r=-0.846--0.586),while it was significantly positively correlated with the relative abundance of the Alphaproteobacteria subphyla(r=0.604).[Conclusion]In summary,wheat may improve its adaptability to increased O3 concentration by reducing the abundance of copiotrophic bacteria and increasing the relative abundance of oligotrophic bacteria,while foliar spraying with EDU may also alleviate wheat O3 stress in wheat through this way.
OzoneEthylenediurea(EDU)Wheat plantRhizosphere soilBacterial community
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