Interspecific plant interaction via root exudates structures the disease suppressiveness of rhizosphere microbiomes

Terrestrial plants can affect the growth and health of adjacent plants via interspecific interaction.Here,we studied the mechanism by which plant root exudates affect the recruitment of the rhizosphere microbiome in adjacent plants—with implications for plant protection—using a tomato(Solanum lycopersicum)–potatoonion(Allium cepa var.agrogatum)intercropping system.First,we showed that the intercropping system results in a disease-suppressive rhizosphere microbiome that protects tomato plants against Verticillium wilt disease caused by the soilborne pathogen Verticillium dahliae.Second,16S rRNA gene sequencing revealed that intercropping with potatoonion altered the composition of the tomato rhizosphere microbiome by promoting the colonization of specific Bacillus sp.This taxon was isolated and shown to inhibit V.dahliae growth and induce systemic resistance in tomato plants.Third,a belowground segregation experiment found that root exudates mediated the interspecific interaction between potatoonion and tomato.Moreover,experiments using split-root tomato plants found that root exudates from potatoonion,especially taxifolin—a flavonoid compound—stimulate tomato plants to recruit plant-beneficial bacteria,such as Bacillus sp.Lastly,ultra-high-pressure liquid chromatography–mass spectrometry analysis found that taxifolin alters tomato root exudate chemistry;thus,this compound acts indirectly in modulating root colonization by Bacillus sp.Our results revealed that this intercropping system can improve tomato plant fitness by changing rhizosphere microbiome recruitment via the use of signaling chemicals released by root exudates of potatoonion.This study revealed a novel mechanism by which interspecific plant interaction modulates the establishment of a disease-suppressive microbiome,thus opening up new avenues of research for precision plant microbiome manipulations.

Changes in bulk soil affect the disease-suppressive rhizosphere microbiome against Fusarium wilt disease

Harnessing disease suppressive microbiomes constitutes a promising strategy for optimizing plant growth.However,relatively lttle information is available about the relationship between bulk and rhizosphere soil microbiomes.Here,the assembly of banana bulk soil and rhizosphere microbiomes was investigated in a mono-culture system consisting of bio-organic(BIO)and organic management practices.Applying BIO practice in newly reclaimed fields resulted in a high-efficiency biocontrol rate,thus providing a promising strategy for pre-control of Fusarium wilt disease.The soil microbiota was further characterized by MiSeq sequencing and quantitative PCR.The results indicate that disease suppression was mediated by the structure of a suppressive rhizosphere microbiome with respect to distinct community composition,diversity and abundance.Overall microbiome suppressiveness was primarily related to a particular set of enriched bacterial taxa affiliated with Pseudomonas,Terrimonas,Cupriavi-dus,Gp6,Ohtaekwangia and Duganella.Finally,struc-tural equation modeling was used to show that the changes in bulk soil bacterial community determined its induced rhizosphere bacterial community,which serves as an important and direct factor in restraining the pathogen.Collectively,this study provides an integrative approach to disentangle the biological basis of disease-suppressive microbiomes in the context of agricultural practice and soil management.