Photosynthetic bacterium Rhodopseudomonas palustris GJ‐22 induces systemic resistance against viruses

Summary Photosynthetic bacteria (PSB) have been extensively used in agriculture to promote plant growth and to improve crop quality. Their potential application in plant disease management, however, is largely overlooked. In this study, the PSB strain Rhodopseudomonas palustris GJ‐22 was investigated for its ability to induce resistance against a plant virus while promoting plant growth. In the field, a foliar spray of GJ‐22 suspension protected tobacco plants against tobacco mosaic virus (TMV). Under axenic conditions, GJ‐22 colonized the plant phyllosphere and induced resistance against TMV. Additionally, GJ‐22 produced two phytohormones, indole‐3‐acetic acid and 5‐aminolevulinic acid, which promote growth and germination in tobacco. Furthermore, GJ‐22‐inoculated plants elevated their immune response under subsequent TMV infection. This research may give rise to a novel biological agent with a dual function in disease management while promoting plant growth. Photosynthetic bacteria are proven to be highly valuable in environmental management, in contrary, their application in biological control of agricultural pests has never been reported. In our research, we discovered a Photosynthetic bacterium Rhodopseudomonas palustris strain GJ‐22 can induce resistance against plant viruses and promote plant growth and seed germination. Our research may give rise to a novel biological agent with potential for growth promotion and disease management while provoking new ideas for comprehensively exploiting photosynthetic bacteria in sustainable agriculture.