Rahnella aquatilis JZ-GX1 alleviates iron deficiency chlorosis in Cinnamomum camphora by secreting desferrioxamine and reshaping the soil fungal community

Abstract

Plant growth-promoting rhizobacteria are important for improving plant iron nutrition, but the interactions among inoculants, host plants and soil microorganisms have not been greatly explored. Rahnella aquatilis JZ-GX1 was applied to treat the increasingly serious iron deficiency chlorosis in Cinnamomum camphora, and the resulting improvement in chlorosis was determined by assessing the contents of chlorophyll, active iron, Fe2+ and antioxidant enzymes in leaves, the effects on the soil microbial community and the metabolism in the rhizosphere by high-throughput sequencing techniques and liquid chromatography–mass spectrometry (LC–MS). The results showed that inoculation with JZ-GX1 significantly increased the chlorophyll content of C. camphora, which promoted the redistribution of active iron in roots and leaves, increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and thus reduced membrane damage in iron-deficient C. camphora caused by reactive oxygen species. According to genome prediction and ultra-performance liquid chromatography–mass spectrometry (UPLC–MS) analysis, the JZ-GX1 strain could secrete desferrioxamine (DFO), and the concentration of DFO in C. camphora rhizosphere was 21-fold higher than that in uninoculated soil. The exogenous application of DFO increased the SPAD and Fe2+ contents in leaves. In addition, the inoculant affected the fungal community structure and composition in the C. camphora rhizosphere soil and increased the abundances of specific taxa, such as Glomus, Mortierella, Trichoderma, and Penicillium. Therefore, R. aquatilis JZ-GX1 application promoted iron absorption in C. camphora trees by secreting DFO and alleviated iron deficiency chlorosis through interactions with the local fungal community.

Integrated microbiome and metabolomics analysis reveal a closer relationship between soil metabolites and bacterial community than fungal community in pecan plantations

“…Notably, 3‐trans‐caffeoyltormentic acid showed a significant positive correlation with the dominant fungi of Saitozyma and Protoglossum (Figure 7), and this phenolic may be the preferred substrate for both of these fungi. It was reported that 3‐trans‐caffeoyltormentic acid is derived from trans‐cinnamic acid (Moeenfard et al, 2014), has insect resistance (Lv et al, 2022), and is associated with pathogenic fungal communities (Kong et al, 2022). Whether Saitozyma and Protoglossum are potentially harmful to soil and plant health needs to be further verified.…”

Biological Control of Pepper Soft Rot Disease Caused by Pectobacterium carotovorum Using Rahnella aquatilis

“…R. aquatilis is considered to have great potential as an antagonist to many bacterial pathogens (Laux et al, 2002;El-Hendawy et al, 2003;Chen et al, 2007Chen et al, , 2009Li et al, 2020a). Also, plant growth promotion by R. aquatilis has been reported (Yuan et al, 2020;Li et al, 2021;Kong et al, 2022;Landa-Acuña et al, 2023). Rahnella aquatilis strains 17 and 55 has been previously reported as potential biological control agents of bacterial spots of tomato caused by Xanthomonas campestris pv.…”