RIN enhances plant disease resistance via root exudate-mediated assembly of diseasesuppressive rhizosphere microbiota

The RIPENING-INHIBITOR(RIN)transcriptional factor is a key regulator governing fruit ripening.While RIN also affects other physiological processes,its potential roles in triggering interactions with the rhizosphere microbiome and plant health are unknown.Here we show that RIN affects microbiome-mediated disease resistance via root exudation,leading to recruitment of microbiota that suppress the soil-borne,phytopathogenic Ralstonia solanacearum bacterium.Compared with the wild-type(WT)plant,RIN mutants had different root exudate profiles,which were associated with distinct changes in microbiome composition and diversity.Specifically,the relative abundances of antibiosis-associated genes and pathogensuppressing Actinobacteria(Streptomyces)were clearly lower in the rhizosphere of rin mutants.The composition,diversity,and suppressiveness of rin plant microbiomes could be restored by the application of 3-hydroxyflavone and riboflavin,which were exuded in much lower concentrations by the rin mutant.Interestingly,RIN-mediated effects on root exudates,Actinobacteria,and disease suppression were evident from the seedling stage,indicating that RIN plays a dual role in the early assembly of diseasesuppressive microbiota and late fruit development.Collectively,our work suggests that,while plant disease resistance is a complex trait driven by interactions between the plant,rhizosphere microbiome,and the pathogen,it can be indirectly manipulated using"prebiotic"compounds that promote the recruitment of disease-suppressive microbiota.

The relative importance of soil moisture in predicting bacterial wilt disease occurrence

Soil-borne plant diseases cause major economic losses globally.This is partly because their epidemiology is difficult to predict in agricultural fields,where multiple environmental factors could determine disease outcomes.Here we used a combination of field sampling and direct experimentation to identify key abiotic and biotic soil properties that can predict the occurrence of bacterial wilt caused by pathogenic Ralstonia solanacearum.By analyzing 139 tomato rhizosphere soils samples isolated from six provinces in China,we first show a clear link between soil properties,pathogen density and plant health.Specifically,disease outcomes were positively associated with soil moisture,bacterial abundance and bacterial community composition.Based on soil properties alone,random forest machine learning algorithm could predict disease outcomes correctly in 75%of cases with soil moisture being the most significant predictor.The importance of soil moisture was validated causally in a controlled greenhouse experiment,where the highest disease incidence was observed at 60%of maximum water holding capacity.Together,our results show that local soil properties can predict disease occurrence across a wider agricultural landscape,and that management of soil moisture could potentially offer a straightforward method for reducing crop losses to R.solanacearum.