Abstract
Azospirillum sp. B510, a free-living nitrogen-fixing bacterium isolated from the stems of rice (Oryza sativa cv. Nipponbare), was investigated to establish effective conditions for the colonization of rice plants. We analyzed the effects of the nitrogen sources KNO3, NH4Cl, urea (CO[NH2]2), and NH4NO3 at different concentrations (0.01–10 mM) on this colonization. Nitrogen promoted plant growth in a concentration-dependent manner, with minor differences being observed among the different nitrogen sources. Bacterial colonization was markedly suppressed on media containing NH4+ concentrations higher than 1 mM. Since concentrations of up to and including 10 mM NH4+ did not exhibit any antibacterial activity, we analyzed several factors affecting the NH4+-dependent inhibition of endophytic colonization, including the accumulation of the reactive oxygen species H2O2 and the secretion of the chemotactic substrate malic acid. The accumulation of H2O2 was increased in rice roots grown on 1 mM NH4Cl. The amounts of malic acid secreted from NH4-grown rice plants were lower than those secreted from plants grown without nitrogen or with KNO3. Although the bacterium exhibited chemotactic activity, moving towards root exudates from plants grown without nitrogen and KNO3-grown plants, this activity was not observed with root exudates from NH4+-grown plants. NH4+, but not NO3−, caused the acidification of growth media, which inhibited plant bacterial colonization. These NH4+-dependent phenomena were markedly suppressed by the stabilization of medium pH using a buffer. These results demonstrate that the type and concentration of nitrogen fertilizer affects the colonization of rice plants by Azospirillum sp. B510.
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Claims 11
Claim · model-written summary
Nitrogen promoted rice growth with increasing concentration and minor differences among sources.
- Taxon
- rice
Oryza sativat0 - Treatment
- Nitrogene0
- Outcome
- plant growthe0
- Direction
- promotede0
- Qualifier
- minor differences being observed among the different nitrogen sourcese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen promoted plant growth in a concentration-dependent manner, with minor differences being observed among the different nitrogen sources.”
t0“Rice Plants”
Claim · model-written summary
NH4+ above 1 mM markedly suppressed Azospirillum colonization of rice.
- Taxon
- riceOryza sativat0
- Treatment
- NH4+ concentrations higher than 1 mMe0
- Interactor
- Azospirillum sp. B510
Azospirillum sp. B510t0symbiont - Outcome
- Bacterial colonizatione0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Bacterial colonization was markedly suppressed on media containing NH4+ concentrations higher than 1 mM.”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
NH4+ up to 10 mM exhibited no antibacterial activity.
- Taxon
- riceOryza sativat0
- Interactor
- Azospirillum sp. B510Azospirillum sp. B510t0symbiont
- Outcome
- antibacterial activitye0
- Qualifier
- up to and including 10 mM NH4+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concentrations of up to and including 10 mM NH4+ did not exhibit any antibacterial activity”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
Rice roots grown on 1 mM NH4Cl accumulated more H2O2.
- Taxon
- riceOryza sativae0
- Organ / stage
- rootse0
- Treatment
- 1 mM NH4Cle0
- Outcome
- accumulation of H2O2e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The accumulation of H2O2 was increased in rice roots grown on 1 mM NH4Cl.”
Claim · model-written summary
NH4-grown rice secreted less malic acid than rice without nitrogen or with KNO3.
- Taxon
- riceOryza sativae0
- Treatment
- NH4-growne0
- Outcome
- amounts of malic acid secretede0
- Direction
- lowere0
- Comparator
- plants grown without nitrogen or with KNO3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The amounts of malic acid secreted from NH4-grown rice plants were lower than those secreted from plants grown without nitrogen or with KNO3.”
Claim · model-written summary
Azospirillum was chemotactic toward exudates from rice grown without nitrogen.
- Taxon
- riceOryza sativat0
- Interactor
- Azospirillum sp. B510Azospirillum sp. B510t0symbiont
- Outcome
- chemotactic activity, moving towards root exudatese0
- Qualifier
- plants grown without nitrogene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the bacterium exhibited chemotactic activity, moving towards root exudates from plants grown without nitrogen and KNO3-grown plants”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
Azospirillum was chemotactic toward exudates from KNO3-grown rice.
- Taxon
- riceOryza sativat0
- Interactor
- Azospirillum sp. B510Azospirillum sp. B510t0symbiont
- Outcome
- chemotactic activity, moving towards root exudatese0
- Qualifier
- KNO3-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the bacterium exhibited chemotactic activity, moving towards root exudates from plants grown without nitrogen and KNO3-grown plants”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
Azospirillum showed no chemotaxis toward exudates from NH4+-grown rice.
- Taxon
- riceOryza sativat0
- Interactor
- Azospirillum sp. B510Azospirillum sp. B510t0symbiont
- Outcome
- this activity was not observede0
- Qualifier
- NH4+-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this activity was not observed with root exudates from NH4+-grown plants”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
NH4+ acidified growth media and thereby inhibited rice bacterial colonization.
- Taxon
- riceOryza sativat0
- Treatment
- NH4+e0
- Interactor
- Azospirillum sp. B510Azospirillum sp. B510t0symbiont
- Outcome
- plant bacterial colonizatione0
- Qualifier
- acidification of growth mediae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NH4+, but not NO3−, caused the acidification of growth media, which inhibited plant bacterial colonization.”
t0“Rice Plants by Azospirillum sp. B510”
Claim · model-written summary
NO3− did not acidify growth media.
- Taxon
- riceOryza sativat0
- Outcome
- acidification of growth mediae0
- Qualifier
- not NO3−e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NH4+, but not NO3−, caused the acidification of growth media”
t0“Rice Plants”
Claim · model-written summary
Buffer stabilization of medium pH markedly suppressed the NH4+-dependent phenomena.
- Taxon
- riceOryza sativat0
- Treatment
- stabilization of medium pH using a buffere0
- Outcome
- NH4+-dependent phenomenae0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These NH4+-dependent phenomena were markedly suppressed by the stabilization of medium pH using a buffer.”
t0“Rice Plants”
The same questions in other papers
nitrogen · growth · Oryza sativa (rice)Positive and negative results
401 papers in the same direction as this paper · 101 in the opposite direction · 8 reporting no difference from an alternative
- negative
- negative
- negative
507 papers more in this group
See all 511 papers →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.