Plant Growth-Promoting Ability of Mycorrhizal Fusarium Strain KB-3 Enhanced by Its IAA Producing Endohyphal Bacterium, Klebsiella aerogenes

Abstract

Fusarium oxysporum KB-3 had been reported as a mycorrhizal fungus of Bletilla striata, which can promote the seed germination and vegetative growth. Endohyphal bacteria were demonstrated in the hyphae of the KB-3 by 16S rDNA PCR amplification and SYTO-9 fluorescent nucleic acid staining. A strain Klebsiella aerogenes KE-1 was isolated and identified based on the multilocus sequence analysis. The endohyphal bacterium was successfully removed from the wild strain KB-3 (KB-3−), and GFP-labeled KE-1 was also transferred to the cured strain KB-3− (KB-3+). The production of indole-3-acetic acid (IAA) in the culturing broths of strains of KE-1, KB-3, KB-3−, and KB-3+ was examined by HPLC. Their IAA productions were estimated using Salkowski colorimetric technique. The highest concentrations of IAA were 76.9 (at 48 h after inoculation), 31.4, 9.6, and 19.4 μg/ml (at 60 h after inoculation), respectively. Similarly, the three fungal cultural broths exhibited plant promoting abilities on the tomato root and stem growth. The results indicated that the ability of mycorrhizal Fusarium strain KB-3 to promote plant growth was enhanced because its endohyphal bacterium, Klebsiella aerogenes KE-1, produced a certain amount of IAA.

Biocompatible Fluorescent Biosensor Reveals the Level and Distribution of Indole-3-Acetic Acid Signals in Plants

“…The recoveries were 101.01 and 99.41%, with corresponding RSD of 1.12–3.69%. These samples were also analyzed by the standard HPLC-MS method . The results of the analysis were largely consistent with those of the former, and the p -value (>0.05) obtained by paired t -test further demonstrated the good agreement between the two methods.…”

“…These samples were also analyzed by the standard HPLC-MS method. 5 The results of the analysis were largely consistent with those of the former, and the p-value (>0.05) obtained by paired t-test further demonstrated the good agreement between the two methods. The above results indicate that the analytical method has reliable precision and accuracy and can be well applied to the detection of real samples.…”

“…Methods such as GC-MS, HPLC, LC-MS, and immunoassays have been established to detect IAA in biological samples. − However, these methods usually require expensive scientific instruments, complex data processing systems, and special immunoglobulins, which severely limit their application. Fluorescence analysis is an important tool for trace, ultratrace, or even molecular level analysis, which has the advantages of good selectivity, less sampling, high sensitivity, as well as simplicity and rapidity, and has started to be applied in plant hormone analysis in recent years .…”

Deciphering the potential of a plant growth promoting endophyte Rhizobium sp. WYJ-E13, and functional annotation of the genes involved in the metabolic pathway

“…Endophytic bacterial strains promoted plant growth via diverse systems, such as producing IAA, cytokinin and jasmonic acid (Harman et al, 2021;Wu W. et al, 2021). For example, the plant growth-promoting ability of mycorrhizal Fusarium strain KB-3 was enhanced by its IAA producing endohyphal bacterium, K. aerogenes (Cheng et al, 2022). Serratia marcescens PLR enhanced lateral root formation through supplying PLR-derived auxin and enhancing auxin biosynthesis in Arabidopsis (Zhang et al, 2022).…”

“…Besides, beneficial endophytes have also been found in many genera, including Stenotrophomonas sp. (Hazarika et al, 2021), Pantoea cypripedii and Kosakonia arachidis , Pennisetum giganteum (Yankey et al, 2022), and Klebsiella aerogenes (Cheng et al, 2022).…”