Abstract
BACKGROUND: Plant growth-promoting bacteria (PGPB) can beneficially modulate rhizosphere microbial communities, potentially improving plant health and reducing disease incidence. Limited research exists on the influence of PGPB inoculation on the rhizosphere microbial communities of apple plants, particularly in soils affected by apple replant disease (ARD). Here, we evaluated the capacity of GFP-labelled Priestia megaterium B1 (designated as P. megaterium B1L5) to colonize the roots of apple plantlets grown in two soils: ARD-affected soil and ARD-unaffected grass soil. We investigated its influence on plant growth in ARD-affected soil and its potential to mitigate ARD-related symptoms. We also assessed how its inoculation modulates the rhizosphere microbial communities, with emphasis on changes that may support plant health, particularly in ARD-affected soils. RESULTS: P. megaterium B1L5 successfully colonized apple roots in both soils 6 days post-inoculation (dpi), but was not detectable at 33 dpi. In ARD-affected soil, plants inoculated with vegetative cells or spores displayed a lower proportion of blackened root tips compared to uninoculated controls. Beta diversity and PERMANOVA analyses demonstrated a significant influence of inoculation on the bacterial communities in both soils at 6 and 33 dpi (p = 0.001). Furthermore, inoculation enriched the rhizosphere of apple plantlets with potential plant-beneficial bacteria, such as Luteimonas, Lysobacter, Pseudomonas, Sphingomonas, Sphingobacterium, Rhodanobacter, Pedobacter and Flavobacterium. In contrast, fungal communities remained largely unaffected by inoculation. Most bacterial and fungal shifts observed in the rhizosphere of inoculated plantlets at 33 dpi did not exhibit similar patterns in uninoculated controls over time, indicating that these shifts were largely driven by the inoculum rather than by plant development or natural microbial succession. CONCLUSIONS: Our results highlight the capacity of P. megaterium B1L5’s to transiently colonize apple plant roots across different soil environments. The observed tendency toward reduced root tip blackening in inoculated plants grown in ARD-affected plants reflects its potential for alleviating stress associated with ARD. Additionally, inoculation with P. megaterium B1L5 promoted beneficial shifts in the rhizosphere microbiome by enriching bacterial taxa commonly linked to plant health. These findings indicate that P. megaterium B1L5 presents a candidate for ARD mitigation, however its long-term efficacy and practical application should be further evaluated.
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Claims 10
Claim · model-written summary
P. megaterium B1L5 colonized apple roots in both soils at 6 days after inoculation.
- Taxon
- apple
Malus domesticae0 - Organ / stage
- rootse0
- Interactor
- P. megaterium B1L5
Priestia megateriume0symbiont - Outcome
- successfully colonized apple rootse0
- Qualifier
- both soils 6 days post-inoculation (dpi)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“P. megaterium B1L5 successfully colonized apple roots in both soils 6 days post-inoculation (dpi)”
Claim · model-written summary
P. megaterium B1L5 was undetectable on apple roots at 33 dpi.
- Taxon
- appleMalus domesticae0
- Interactor
- P. megaterium B1L5Priestia megateriume0symbiont
- Outcome
- not detectable at 33 dpie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“P. megaterium B1L5 successfully colonized apple roots in both soils 6 days post-inoculation (dpi), but was not detectable at 33 dpi.”
Claim · model-written summary
Vegetative cell inoculation lowered blackened root tip proportion in ARD soil relative to controls.
- Taxon
- appleMalus domesticat0
- Treatment
- vegetative cellse0
- Interactor
- vegetative cellse0symbiont
- Outcome
- proportion of blackened root tipse0
- Direction
- lowere0
- Comparator
- uninoculated controlse0
- Setting
- ARD-affected soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In ARD-affected soil, plants inoculated with vegetative cells or spores displayed a lower proportion of blackened root tips compared to uninoculated controls.”
t0“apple plantlets”
Claim · model-written summary
Spore inoculation lowered blackened root tip proportion in ARD soil relative to controls.
- Taxon
- appleMalus domesticat0
- Treatment
- sporese0
- Interactor
- Priestia megaterium B1L5Priestia megateriumt0symbiont
- Outcome
- proportion of blackened root tipse0
- Direction
- lowere0
- Comparator
- uninoculated controlse0
- Setting
- ARD-affected soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In ARD-affected soil, plants inoculated with vegetative cells or spores displayed a lower proportion of blackened root tips compared to uninoculated controls.”
t0“Transient colonization by Priestia megaterium B1L5 alters the structure of the rhizosphere microbiome towards potential plant beneficial bacterial groups in apple plantlets”
Claim · model-written summary
Inoculation significantly altered apple rhizosphere bacterial communities in both soils at 6 and 33 dpi.
- Taxon
- appleMalus domesticat0
- Treatment
- inoculatione0
- Outcome
- bacterial communitiese0
- Value
- p = 0.001e0
- Qualifier
- both soils at 6 and 33 dpie0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Beta diversity and PERMANOVA analyses demonstrated a significant influence of inoculation on the bacterial communities in both soils at 6 and 33 dpi (p = 0.001).”
t0“apple plantlets”
Claim · model-written summary
Inoculation enriched potential beneficial bacteria in apple rhizospheres.
- Taxon
- appleMalus domesticae0
- Treatment
- inoculatione0
- Outcome
- potential plant-beneficial bacteriae0
- Direction
- enrichede0
- Qualifier
- Luteimonas, Lysobacter, Pseudomonas, Sphingomonas, Sphingobacterium, Rhodanobacter, Pedobacter and Flavobacteriume0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Furthermore, inoculation enriched the rhizosphere of apple plantlets with potential plant-beneficial bacteria, such as Luteimonas, Lysobacter, Pseudomonas, Sphingomonas, Sphingobacterium, Rhodanobacter, Pedobacter and Flavobacterium.”
Claim · model-written summary
Apple rhizosphere fungal communities were largely unaffected by inoculation.
- Taxon
- appleMalus domesticat0
- Treatment
- inoculatione0
- Outcome
- fungal communitiese0
- Direction
- largely unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, fungal communities remained largely unaffected by inoculation.”
t0“apple plantlets”
Claim · model-written summary
Most 33 dpi microbial shifts in inoculated apple rhizospheres lacked similar patterns in uninoculated controls.
- Taxon
- appleMalus domesticat0
- Outcome
- bacterial and fungal shiftse0
- Direction
- did not exhibit similar patternse0
- Qualifier
- 33 dpie0
- Comparator
- uninoculated controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most bacterial and fungal shifts observed in the rhizosphere of inoculated plantlets at 33 dpi did not exhibit similar patterns in uninoculated controls over time”
t0“apple plantlets”
Claim · model-written summary
Authors infer the 33 dpi microbial shifts were driven primarily by the inoculum.
- Taxon
- appleMalus domesticat0
- Outcome
- these shiftse0
- Qualifier
- largely driven by the inoculume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indicating that these shifts were largely driven by the inoculum rather than by plant development or natural microbial succession.”
t0“apple plantlets”
Claim · model-written summary
Authors identify P. megaterium B1L5 as a candidate for ARD mitigation requiring long term evaluation.
- Taxon
- appleMalus domesticat0
- Interactor
- P. megaterium B1L5Priestia megateriume0symbiont
- Outcome
- candidate for ARD mitigatione0
- Qualifier
- long-term efficacy and practical application should be further evaluatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These findings indicate that P. megaterium B1L5 presents a candidate for ARD mitigation, however its long-term efficacy and practical application should be further evaluated.”
t0“apple plantlets”
The same questions in other papers
inoculation · soil: biology · Malus domestica (apple)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- no effect
- positive
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