Effects Of Rhizoplane Pseudomonas Spp.on The Disease Resistance Of Invasive Plant Solidago Canadensis L.

The harmonious development of biodiversity is largely ascribed to the potential function of microorganisms.Changes in physiological and biochemical processes where microorganisms interact with other species will show differences in regulatory pathways and functions.Previous studies on plant invasion focused on the direct or indirect effects between species.While the significant role of symbionts or recruited microbial communities in invasive species was neglected.In this study,the effects of rhizoplane Pseudomonas spp.on the disease-resistance of Solidago canadensis was explored,especially the potential function of rhizoplane Pseudomonas spp.on the growth and defense of plant.Furthermore,preliminary immune defense pathways and mechanisms were studied.The main results are as follows:?1?Eighty-nine strains were isolated from rhizoplane of S.canadensis.At the level of genus,culturable bacteria from rhizoplane between high and low invaded communities were quite different,and Pseudomonas spp.was widely distributed in high invaded communities of S.canadensis.Methods of bioinformatics analysis and plate culture were used to confirm if some Pseudomonas were potentially disease-resistant.?2?Five strains rhizoplane Pseudomonas with great antibacterial property were selected for next experiments.They could significantly alleviate pathogenicity degree of detached leaves of S.canadensis.Compared with native plant S.decurrens,detached leaves from invasive S.canadensis had better disease-resistance whether treated with Pseudomonas or not.In addition,metabolites extracted from representative strains were significantly disease-resistant and antibacterial.?3?When S.canadensis exposed to the stress of pathogenic fungi,inoculation with rhizoplane Pseudomonas significantly(F_9,42=5.093 P<0.001)increased biomass of shoots of S.canadensis.Besides,rhizoplane Pseudomonas decreased the levels of intracellular reactive oxygen species while increased cell viability.Therefore,interactions with rhizoplane Pseudomonas could enhance the growth and disease-resistance of S.canadensis.?4?Under the stress of pathogenic fungi,interactions with rhizoplane Pseudomonas could significantly decrease hormone levels of S.canadensis.Therefore,the pathogenic stress and immune response of S.canadensis by hormone regulation pathway could be relieved by interactions with rhizoplane Pseudomonas.Our results indicated that S.canadensis might recruit bacteria communities around their rhizoplane especially for the high invasion process.These rhizoplane bacteria could synergistically enhance the resistance of S.canadensis to pathogenic stress by affecting the production of intracellular reactive oxygen species and hormone,and providing survival advantage for S.canadensis.