Effects of photosynthetic bacteria Rhodopseudomonas palustris Atp2 protein on growth and stress resistance in rice

【Objective】 To investigate the effects of the photosynthetic bacteria Rhodopseudomonas palustris PSB06 Atp2 protein on the growth，defence enzyme activity and the transcript levels of defense-related genes in rice，and to provide theoretical basis for the popularization of the use of biocontrol bacteria in rice. 【Method】 Rice variety CO-39 was used as the test material，and rice seeds and leaves were treated with 3 treatment solutions of 0（distilled water，CK），20 and 50 μg/mL Atp2 protein，the chlorophyll a/b and the hydrogen peroxide（H₂O₂）content were detected，as well as the activities of rice defense-related enzymes such as peroxidase（POD），catalase（CAT），superoxide dismutase（SOD）， glutathione reductase（GR），phenylalanine ammonia-lyase（PAL），polyphenol oxidase（PPO）in rice，and the transcript levels of defense-related genes（OsWRKY70，OsLOX1，OsAOS2，OsPR1a，OsCHT1 and OsPAL1）in rice were detected by real-time fluorescence quantitative PCR. 【Result】 Compared with CK，chlorophyll a/b was significantly（P<0.05，the same below）or extremely significantly（P<0.01，the same below）increased in rice after Atp2 protein treatment of rice leaves，while chlorophyll a/b did not change significantly after treatment of seeds（P>0.05）；H₂O₂ content in rice was elevated in all Atp2 protein treatments，with extremely significant elevation in the content of H₂O₂ after treatment of leaves； POD and CAT activities in rice were significantly or extremely significantly decreased after Atp2 protein treatment；SOD， GR and PAL activities in rice were extremely significantly increased after Atp2 protein treatment；PPO activity in rice was significantly or extremely significantly increased after Atp2 protein treatment of seeds，whereas PPO activity was signifi-cantly or extremely significantly decreased after treatment of leaves. After Atp2 protein treatment，expressions of rice defense genes OsWRKY70，OsLOX1，OsAOS2（except 50 μg/mL Atp2 protein treated rice leaves），OsPR1a and OsCHT1 were all up-regulated，of which the expression of OsWRKY70，OsLOX1 and OsCHT1 genes were either significantly or extremely significantly up-regulated；the expression of OsPAL1 gene was extremely significantly up-regulated after the treatment of seeds with Atp2 protein，and OsPAL1 gene expression was extremely significantly up-regulated after the treatment of leaves. 【Conclusion】 The R. palustris PSB06 Atp2 protein of R. palustris has good growth-promoting and stressresistant effect on rice，which has the potential for promotion and application.