Abstract
Abstract Background Co-inoculation of maize with Herbaspirillum seropedicae and humic substances increases the sizes of plant-associated bacterial populations and enhances grain yields under laboratory and field conditions. Root exudation is a key mechanism in the regulation of plant-bacterial interactions in the rhizosphere; humic matter supplementation is known to change the exudation of H + ions and organic acids from maize roots. Our starting premise was that H. seropedicae and humic acids would modify maize seedling exudation profiles. We postulated that a better understanding of these shifts in exudate profiles might be useful in improving the chemical environment to promote better performance of plant growth-promoting bacteria delivered as bioinoculants. Thus, root exudates of maize were collected and analyzed by gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance ( 1 H NMR). Results Nitrogenous compounds, fatty acids, organic acids, steroids, and terpenoid derivatives were the main structural moieties found in root exudates. Significant changes in exudation patterns occurred 14 days after the initiation of experiments. Quantities of fatty acids, phenols, and organic acids exuded by seedlings treated with humic acids alone differed from the quantities exuded in other treatments. Seedlings treated with H. seropedicae or H. seropedicae in combination with humic acids exuded a diversity of nitrogenous compounds, most of which had heterocyclic structures. Twenty-one days after initiating the experiment, seedlings treated with H. seropedicae alone exuded elevated quantities of steroids and terpenoid derivatives related to precursors of gibberellic acids (kaurenoic acids). Conclusions Changes in root exudation profiles induced by our treatments became most marked 14 and 21 days after initiation of the experiment; on those days, we observed (i) increased fatty acid exudation from seedlings treated only with humic acids and (ii) increased exudations of nitrogenated compounds and terpenes from seedlings treated only with H. seropedicae . Improved knowledge on the effects of bacterial inoculants and supplementation with humates on plant exudate composition may contribute substantially to improved understanding of plant metabolic responses and lead to new approaches in the use of selected compounds as additives in bioinoculant formulations that will modulate the cross-talk between bacteria and plants, thereby improving crop yields.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
Nitrogenous compounds, fatty acids, organic acids, steroids and terpenoid derivatives were main maize root exudate moieties.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogenous compounds, fatty acids, organic acids, steroids, and terpenoid derivatives were the main structural moieties found in root exudates.”
t0“maize seedlings”
Claim · model-written summary
Maize root exudation patterns changed significantly after 14 days.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant changes in exudation patterns occurred 14 days after the initiation of experiments.”
t0“maize seedlings”
Claim · model-written summary
Humic acid alone altered maize seedling exudation of fatty acids, phenols and organic acids versus other treatments.
- Treatment
- humic acids alonee0
- Outcome
- Quantities of fatty acids, phenols, and organic acids exudede0
- Direction
- differede0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Quantities of fatty acids, phenols, and organic acids exuded by seedlings treated with humic acids alone differed from the quantities exuded in other treatments.”
t0“maize seedlings”
Claim · model-written summary
H. seropedicae alone induced diverse nitrogenous compound exudation.
- Treatment
- H. seropedicaee0
- Interactor
- H. seropedicaeHerbaspirillum seropedicaee0symbiont
- Outcome
- a diversity of nitrogenous compoundse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedlings treated with H. seropedicae or H. seropedicae in combination with humic acids exuded a diversity of nitrogenous compounds, most of which had heterocyclic structures.”
t0“maize seedlings”
Claim · model-written summary
H. seropedicae with humic acids induced diverse nitrogenous compound exudation.
- Treatment
- H. seropedicae in combination with humic acidse0
- Interactor
- H. seropedicaeHerbaspirillum seropedicaee0symbiont
- Outcome
- a diversity of nitrogenous compoundse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedlings treated with H. seropedicae or H. seropedicae in combination with humic acids exuded a diversity of nitrogenous compounds, most of which had heterocyclic structures.”
t0“maize seedlings”
Claim · model-written summary
After 21 days, H. seropedicae alone elevated maize seedling exudation of steroids and terpenoid derivatives.
- Treatment
- H. seropedicae alonee0
- Interactor
- H. seropedicaeHerbaspirillum seropedicaee0symbiont
- Outcome
- quantities of steroids and terpenoid derivativese0
- Direction
- elevatede0
- Qualifier
- Twenty-one days after initiating the experimente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Twenty-one days after initiating the experiment, seedlings treated with H. seropedicae alone exuded elevated quantities of steroids and terpenoid derivatives related to precursors of gibberellic acids (kaurenoic acids).”
t0“maize seedlings”
The same questions in other papers
Herbaspirillum seropedicae · molecular: metabolites · Zea mays (maize)Results agree
2 papers in the same direction as this paper
- positive
- positive
other · ecology: diversity · Zea mays (maize)Positive and negative results
1 in the opposite direction
- no effect
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.