Induced Disease Resistance By Piriformospora Indica And Sebacina Vermifera In Tomato

Plants are potential hosts for a broad-spectrum of microbial organisms, resulting in two different types of associations including mutualistic and pathogenic relationships. Most of plants live with arbuscular mycorrhizal fungi and ectomycorrhizal fungi to form symbiotic associations. In such mutualistic associations, the host plant delivers photoassimilates to the fungus, and the fungus promotes access of the roots to nutrients in the soil. In comparison to arbuscular mycorrhizal fungi, a large number of fungal species form ectomycorrhizal associations, mainly among the basidiomycetes and ascomycetes. Fungi in symbiotic associations provide benefits to crop plants by promoting growth and development as well as increasing tolerance/resistance against abiotic and biotic stress.The endophyte Piriformospora indica, which belongs to the Sebacinales order of the Basidiomycota, was firstly discovered in India and is a cultivable, micorrhiza-like fungus. P. indica colonizes roots of a range of plant species including Arabidopsis, tobacco, wheat, barley, maize, and even colonize some plant species of the Brassicaceae, which do not form a symbiosis with arbuscular mycorrhizal fungi. Hyphae of P. indica can grow on the root surface, in the outer cell layers of the roots, and within the root cells, and form chlamydospores within root cells. Once colonized, P. indica can survive in plant roots for a long time period.Increasing evidence has demonstrated that P. indica has pleiotropic effects on multiple aspects of plant growth and development as well as in response to environmental stress. Studies have showed that P. indica can promote growth in many plant species and enhance grain yields in barley and wheat, which is largely due to accelerated plant development by improving nutrient supply. It was also found that colonization of P. indica can enhance tolerance to drought and salinity stress in barley and Arabidopsis, and induce disease resistance against root and foliar pathogens by regulating innate immunity and defense response. Furthermore, Sebacina vermifera, another member of the Sebacinales, has also been shown to promote growth and fitness of Nicotiana attenuata by modulating ethylene signaling.In the present study, we examined whether P. indica and S. vermifera, two known members of the Sebacinales, can colonize roots of tomato plants and their effects on vegetable growth, fruit development and disease resistance. We also explored the possible role of P. indica and S. vermifera in phosphorus nutrition of tomato plants under normal and low phosphorus conditions. Our results indicate that P. indica and S. vermifera can colonize and promote vegetable growth and fruit development. The fruits number were more than noninoculated plants,but the single fruit weight were no difference between inoculated and noninoculated plant. Analysis of Botrytis cinerea and Pseudomonas syringae pv tomato DC3000 infections was done. The disease lesions on the inoculated plant were reduced than that on the noninoculated plants but the pathogenesis-related proteins genes PR-la, PR-2a,2b PR-3a,3b expression were no difference. Suggest that P. indica and S. vermifera might induce systemic disease resistance by an as yet unknown signaling pathway which has no relation to SA and JA. Our results also indicate that both endophytoic fungi can increase phosphorus uptake in tomato plants under normal and low phosphorus condition.