Isolation and characterisation of endophytic actinobacteria and their effect on the early growth and nodulation of lucerne (Medicago sativa L.)

Le, Xuyen H.; Franco, Christopher M. M.; Ballard, Ross; Drew, Elizabeth

doi:10.1007/s11104-015-2652-9

Cited by 33 publications

(23 citation statements)

References 35 publications

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“…This similarity suggests that Micromonospora is capable of xing nitrogen [74,75]. Streptomycetaceae are reported to possess the ability to colonize the roots of Pisum sativum [80] and M. sativa [81] and they could also increase root nodulation e ciency and facilitated nutrient assimilation of their host plants. These ndings suggest that a functional symbiosis with effective nodulation and nitrogen xation in soybean may speci cally promotesthe enrichment of bene cial microbes.…”

Section: Discussionmentioning

confidence: 99%

The symbiotic capacity of rhizobium shapes root-associated microbiomes

Liu¹,

Ma²,

Chen³

et al. 2020

Preprint

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Background: Root-microbiome interactions are of central importance for plant performance and yield. A distinctive feature of legumes in this context is that they engage in symbiosis with rhizobia, which are abundant in soils and include both symbiotic and non-symbiotic bacterial strains. If and how the capacity of rhizobia to form symbiosis modulates root-associated microbiomes are not well understood. Results: We address this question by inoculating soybean (Glycine max) plants with wild type (WT) or a noeI mutant of Bradyrhizobium diazoefficiens. The noeI mutant produces a defective Nod factor and is thus compromised in its ability to establish functional symbiosis. Compared to soybean plants inoculated with WT rhizobia, plants inoculated with the noeI mutant showed a significant decrease in nodulation and root-flavonoid exudation, and exhibited strong changes in microbiome assembly in the rhizosphere and the rhizoplane. NoeI mutant-inoculated roots exhibited reduced diversity, co-occurrence interactions and a substantial depletion of beneficial microbes on the roots. The effects of the noeI mutation were absent in soils without plants, demonstrating that they are plant dependent. Complementation experiments showed that flavonoid supplementation is sufficient to restore recruitment of beneficial microbes. Conclusion: The results illustrate that the capacity of a rhizobium to form microbial symbiosis dramatically alters root-associated microbiomes, most likely by changing root exudation patterns. The results of this study have important implications for our understanding of the evolution of plant-microbiome interactions in the context of plant-bacterial symbioses.

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Section: Discussionmentioning

confidence: 99%

The symbiotic capacity of rhizobium shapes root-associated microbiomes

Liu¹,

Ma²,

Chen³

et al. 2020

Preprint

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“…Beneficial endophytic actinobacteria with potential biocontrol characteristics have been previously isolated from diverse plant species, such as tomato (Passari et al, 2016a), cereal crops (Patel et al, 2018), and legumes (Le et al, 2016;Vijayabharathi et al, 2018). Endophytic actinobacteria augment plant growth directly through nutrient solubilization, modulation of hormone levels, nitrogen fixation (Palaniyandi et al, 2013;Golinska et al, 2015;Figueiredo et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Phylogenetic and Functional Characterization of Culturable Endophytic Actinobacteria Associated With Camellia spp. for Growth Promotion in Commercial Tea Cultivars

Borah

Thakur

2020

Front. Microbiol.

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Plant associated endophytic actinobacteria may contribute to plant growth and defense by direct or indirect methods. Our aim was to evaluate the plant growth promoting and antifungal activities of endophytic actinobacteria associated with Camellia spp. and related genera, Eurya to find potent plant growth promoting strains that could be applied in future microbe based bioformulations. We isolated 46 endophytic actinobacteria based on morphological characteristics of the isolates. 16S rRNA gene sequence analysis showed that the strains represented nine actinobacterial genera, Nocardia, Amycolatopsis, Streptomyces, Pseudonocardia, Kribbella, Actinomadura, Microbispora, Rothia and Saccharomonospora. In vitro functional characterization of the isolates for plant growth promoting (PGP) traits revealed many potent PGP isolates such as, SA1 and S43 which showed all the tested PGP traits, i.e., phosphate solubilization, indole-3-acetic acid (IAA), ammonia, siderophore and chitinase production. Out of the 46 endophytic actinobacteria isolates, 21 showed inhibition against atleast one test fungal phytopathogen and, isolates SA25 and SA29 exhibited broad spectrum antifungal activity against all the tested phytopathogens. Most of the endophytic actinobacteria isolates having antifungal activity were positive for the presence of chitinase, NRPS (Non-ribosomal peptides synthetase) or PKS-1 (Polyketide Synthase) gene, suggesting the presence of distinctive mechanisms to inhibit the growth of pathogenic plant fungi. ARDRA (Amplified Ribosomal DNA Restriction analysis) and BOX-PCR fingerprinting analysis of the potent isolates with antagonistic activity grouped the isolates into 5 and 4 separate clusters, respectively. In addition, an assessment using bonitur scale revealed the top ranked isolates based on their PGP and biocontrol traits. Further detection of IAA production by the top ranked actinobacterial isolates namely, SA1, T1LA3 and S85 by using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) was done. Endophytic actinobacteria isolates, namely, SA1, T1LA3, and SA14 were further tested for their efficacy in promoting the growth of commercial tea clones, namely, TV1, Frontiers in Microbiology | www.frontiersin.org 1 February 2020 | Volume 11 | Article 318Borah and Thakur Bioactive Endophytic Actinobacteria in Tea TV9, TV18, and TV22 in nursery conditions. All the endophytic isolates tested showed significant differences (P ≤ 0.05) in terms of plant growth promoting parameters in the treated plants compared to untreated control and may, thus be, deemed as potential candidates for application in bioformulations for tea growth.

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“…Blast infected and healthy rice were harvested when they were 2, 4, 7, 11, 16 and 19 weeks old, respectively, and then lifted into paper bags and transported to the laboratory. The plants were washed thoroughly and dried overnight, and then divided into root, stem, sheath and leaf tissues, and subjected to a surface sterilization procedure as described previously by Xiong et al The dried plant segments were cut into pieces (length 10 mm) and transferred onto four isolation media: humic acid vitamin B agar, mannitol soybean agar (MS), tap water yeast extract agar and water agar (WA) medium . Each medium was supplemented with 20 mg L −1 nalidixic acid and 50 mg L −1 benomyl as antibacterial and antifungal agents, respectively.…”

Section: Methodsmentioning

confidence: 99%