Abstract
Sugarcane is an important sugar and energy crop worldwide, requiring a large amount of nitrogen (N). However, excessive application of synthetic N fertilizer causes environmental pollution in farmland. Endophytic nitrogen-fixing bacteria (ENFB) provide N nutrition for plants through biological N fixation, thus reducing the need for chemical fertilizers. The present study investigated the effect of the N-fixing endophytic strain Enterobacter roggenkampii ED5 on phytohormone indole-3-acetic acid (IAA), N-metabolism enzyme activities, microbial community compositions, and N cycle genes in sugarcane rhizosphere soil at different N levels. Three levels of 15 N-urea, such as low N (0 kg/ha), medium N (150 kg/ha), and high N (300 kg/ha), were applied. The results showed that, after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days). The nitrate reductase (NR) activity showed a downward trend. However, the glutamine synthase (GS) and NADH-glutamate dehydrogenase (NADH-GDH) activities were significantly enhanced compared to the control under the high N condition, and the GS and NR genes had the highest expression at 180 and 120 days, respectively, at the low N level. The total N content in the roots, stems, and leaves of sugarcane was higher than the control. The 15 N atom % excess of sugarcane decreased significantly under medium N condition, indicating that the medium N level was conducive to N fixation in strain ED5. Metagenome analysis of sugarcane rhizosphere soil exhibited that the abundance of N-metabolizing microbial richness was increased under low and high N conditions after inoculation of strain ED5 at the genus level, while it was increased at the phylum level only under the low N condition. The LefSe (LDA > 2, p < 0.05) found that the N-metabolism-related differential microorganisms under the high N condition were higher than those under medium and low N conditions. It was also shown that the abundance of nifDHK genes was significantly increased after inoculation of ED5 at the medium N level, and other N cycle genes had high abundance at the high N level after inoculation of strain ED5. The results of this study provided a scientific reference for N fertilization in actual sugarcane production.
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Claims 13
Claim · model-written summary
ED5 increased leaf IAA 68.82% under low nitrogen at 60 days.
- Taxon
- sugarcanee0
- Organ / stage
- leavese0
- Treatment
- inoculating strain ED5e0
- Interactor
- strain ED5e0symbiont
- Outcome
- IAA contente0
- Direction
- increasede0
- Value
- 68.82%e0
- Qualifier
- under low N condition at the seedling stage (60 days)e0
Not reportedComparator
Verbatim
e0“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Nitrate reductase activity trended downward after ED5 inoculation.
- Taxon
- sugarcanet0
- Treatment
- strain ED5e1
- Gene
- nitrate reductase (NR)e0
- Outcome
- nitrate reductase (NR) activitye0
- Direction
- downward trende0
Not reportedComparator
Verbatim
e0“The nitrate reductase (NR) activity showed a downward trend”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Glutamine synthase activity rose under high nitrogen.
Verbatim
e0“the glutamine synthase (GS) and NADH-glutamate dehydrogenase (NADH-GDH) activities were significantly enhanced compared to the control under the high N condition”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
NADH-glutamate dehydrogenase activity rose under high nitrogen.
Verbatim
e0“the glutamine synthase (GS) and NADH-glutamate dehydrogenase (NADH-GDH) activities were significantly enhanced compared to the control under the high N condition”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
GS expression peaked at 180 days under low nitrogen.
Verbatim
e0“the GS and NR genes had the highest expression at 180 and 120 days, respectively, at the low N level”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
NR expression peaked at 120 days under low nitrogen.
Verbatim
e0“the GS and NR genes had the highest expression at 180 and 120 days, respectively, at the low N level”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Total nitrogen rose in sugarcane roots, stems and leaves.
Verbatim
e0“The total N content in the roots, stems, and leaves of sugarcane was higher than the control”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Sugarcane nitrogen isotope excess decreased under medium nitrogen.
- Taxon
- sugarcanee0
- Treatment
- strain ED5e1
- Outcome
- 15 N atom % excesse0
- Direction
- decreasede0
- Qualifier
- under medium N conditione0
Not reportedComparator
Verbatim
e0“The 15 N atom % excess of sugarcane decreased significantly under medium N condition”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Rhizosphere nitrogen-metabolizing microbial richness rose at genus level under low and high nitrogen.
- Taxon
- sugarcanet0
- Treatment
- inoculation of strain ED5e0
- Outcome
- abundance of N-metabolizing microbial richnesse0
- Direction
- increasede0
- Qualifier
- under low and high N conditionse0
Not reportedComparator
Verbatim
e0“the abundance of N-metabolizing microbial richness was increased under low and high N conditions after inoculation of strain ED5 at the genus level”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Rhizosphere microbial richness rose at phylum level only under low nitrogen.
- Taxon
- sugarcanet0
- Treatment
- strain ED5e0
- Outcome
- N-metabolizing microbial richnesse0
- Direction
- increasede0
- Qualifier
- only under the low N conditione0
Not reportedComparator
Verbatim
e0“the abundance of N-metabolizing microbial richness was increased under low and high N conditions after inoculation of strain ED5 at the genus level, while it was increased at the phylum level only under the low N condition”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
High nitrogen had more differential nitrogen-metabolism microorganisms than medium or low nitrogen.
Verbatim
e0“N-metabolism-related differential microorganisms under the high N condition were higher than those under medium and low N conditions”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
ED5 significantly increased nifDHK abundance under medium nitrogen.
- Taxon
- sugarcanet0
- Treatment
- inoculation of ED5e0
- Outcome
- abundance of nifDHK genese0
- Direction
- increasede0
- Qualifier
- at the medium N levele0
Not reportedComparator
Verbatim
e0“the abundance of nifDHK genes was significantly increased after inoculation of ED5 at the medium N level”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
Claim · model-written summary
Other nitrogen cycle genes were abundant under high nitrogen after ED5 inoculation.
Verbatim
e0“other N cycle genes had high abundance at the high N level after inoculation of strain ED5”
t0“sugarcane”
e1“after inoculating strain ED5, the IAA content in sugarcane leaves was significantly increased by 68.82% under low N condition at the seedling stage (60 days)”
The same questions in other papers
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- no effect
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1 paper in the same direction as this paper
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.