Paper · 2026 · Stress Biology

Auxin accumulation in cereals after infection by Fusarium graminearum: putative biosynthetic pathways and preferences

Huanzhang Shang; Bo Ji; Thérèse Ouellet; et al.

6
claims
9
verbatim quotes
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citations
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research areas
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Open access · cc-by

Abstract

Indole-3-acetic acid (IAA) is a major naturally occurring auxin that shows extensive accumulation in cereal plants during the first few days of infection by the phytopathogen Fusarium graminearum. Apart from its positive effects on plant growth, empirical studies have suggested that it is a virulence factor that alters the host's nutritional level and fine-tunes the plant's immune responses, especially salicylic acid-mediated defenses. Plant and fungus genomic studies have predicted that their genomes carry the required genes for L-tryptophan-dependent IAA biosynthetic pathways. In recent decades, genetic and genomic studies have facilitated the description of L-tryptophan (L-TRP)-dependent IAA biosynthetic pathways in F. graminearum and its host plants. The present review illustrates and summarizes the putative and preference molecular networks related to extensive IAA accumulation in wheat heads triggered by infection with F. graminearum, based on the available knowledge about the endogenous IAA biosynthetic pathways in F. graminearum and wheat plants. Meanwhile, infection by F. graminearum could preferentially trigger L-TRP's conversion into serotonin and even phytomelatonin via tryptamine in wheat heads as well. Lower concentrations of them have been shown to stimulate IAA accumulation or mimic IAA to promote plant growth. However, upon that hardly provides sufficient information for regarding alternative methods of controlling scab epidemics. In combination with dissecting IAA biosynthetic pathways using genetic approaches exhibits many difficulties, we thus highlight that ongoing efforts should focus more on identifying the fungal effectors involved in extensive IAA accumulation in cereals in order to understand their potential roles in wheat-F. graminearum interactions. Advancements in molecular breeding programs will further accelerate the application of these molecular targets, allowing for the development of more scab-resistant wheat cultivars and resulting in the effective and environmentally friendly suppression of scab epidemics.

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Claims 6

Observationobservedreview summarybasis n/a

Claim · model-written summary

IAA accumulates in cereal plants during early Fusarium graminearum infection.

Taxon
cereal plantse0
Interactor
Fusarium graminearumFusarium graminearume0pathogen
Outcome
Indole-3-acetic acid (IAA)e0
Direction
extensive accumulatione0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Fusarium graminearum
Fusarium graminearum · InteractorScot Nelson from Honolulu, USA · CC0 · Wikimedia Commons ↗

Verbatim

e0

“Indole-3-acetic acid (IAA) is a major naturally occurring auxin that shows extensive accumulation in cereal plants during the first few days of infection by the phytopathogen Fusarium graminearum”

✓ located verbatim in the source · abstract, characters 0–195 · show in text ↑
Mechanismhypothesisreview summarybasis n/a

Claim · model-written summary

IAA has been suggested as a virulence factor that alters host nutrition and immunity.

Taxon
cerealst0
Interactor
Fusarium graminearumFusarium graminearumt0pathogen
Compound
salicylic acide0
Outcome
host's nutritional level and fine-tunes the plant's immune responsese0
Qualifier
virulence factore0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Fusarium graminearum
Fusarium graminearum · InteractorScot Nelson from Honolulu, USA · CC0 · Wikimedia Commons ↗

Verbatim

e0

“empirical studies have suggested that it is a virulence factor that alters the host's nutritional level and fine-tunes the plant's immune responses, especially salicylic acid-mediated defenses”

✓ located verbatim in the source · abstract, characters 246–438 · show in text ↑
t0

“cereals after infection by Fusarium graminearum”

✓ located verbatim in the source · title, characters 22–69 · show in text ↑
Observationauthor interpretationreview summarybasis n/a

Claim · model-written summary

Plant and fungal genomes are predicted to contain genes for L-tryptophan-dependent IAA biosynthesis.

Taxon
cerealst0
Interactor
Fusarium graminearumFusarium graminearumt0pathogen
Outcome
required genes for L-tryptophan-dependent IAA biosynthetic pathwayse0

Not reportedDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Fusarium graminearum
Fusarium graminearum · InteractorScot Nelson from Honolulu, USA · CC0 · Wikimedia Commons ↗

Verbatim

e0

“Plant and fungus genomic studies have predicted that their genomes carry the required genes for L-tryptophan-dependent IAA biosynthetic pathways”

✓ located verbatim in the source · abstract, characters 440–584 · show in text ↑
t0

“cereals after infection by Fusarium graminearum”

✓ located verbatim in the source · title, characters 22–69 · show in text ↑
Mechanismhypothesisreview summarybasis n/a

Claim · model-written summary

F. graminearum infection may preferentially trigger conversion of L-TRP to serotonin and phytomelatonin in wheat heads.

Organ / stage
wheat headse0
Interactor
F. graminearumFusarium graminearume0pathogen
Compound
L-TRPe0
Outcome
L-TRP's conversion into serotonin and even phytomelatonin via tryptaminee0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Triticum aestivum
Triticum aestivum · TaxonRasbak · CC BY-SA 3.0 · Wikimedia Commons ↗
Fusarium graminearum
Fusarium graminearum · InteractorScot Nelson from Honolulu, USA · CC0 · Wikimedia Commons ↗

Verbatim

e0

“infection by F. graminearum could preferentially trigger L-TRP's conversion into serotonin and even phytomelatonin via tryptamine in wheat heads”

✓ located verbatim in the source · abstract, characters 1082–1226 · show in text ↑
Associationobservedreview summarybasis n/a

Claim · model-written summary

Low concentrations of these metabolites have been reported to stimulate IAA accumulation.

Taxon
cerealst0
Interactor
Fusarium graminearumFusarium graminearumt0pathogen
Compound
theme0
Outcome
IAA accumulatione0
Direction
stimulatee0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Fusarium graminearum
Fusarium graminearum · InteractorScot Nelson from Honolulu, USA · CC0 · Wikimedia Commons ↗

Verbatim

e0

“Lower concentrations of them have been shown to stimulate IAA accumulation or mimic IAA to promote plant growth”

✓ located verbatim in the source · abstract, characters 1236–1347 · show in text ↑
t0

“cereals after infection by Fusarium graminearum”

✓ located verbatim in the source · title, characters 22–69 · show in text ↑
Recommendationauthor interpretationoriginal resultbasis n/a

Claim · model-written summary

The authors recommend identifying fungal effectors involved in cereal IAA accumulation.

Taxon
cerealse0
Interactor
fungale0pathogen
Outcome
identifying the fungal effectors involved in extensive IAA accumulatione0

Verbatim

e0

“ongoing efforts should focus more on identifying the fungal effectors involved in extensive IAA accumulation in cereals”

✓ located verbatim in the source · abstract, characters 1605–1724 · show in text ↑