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
Claim · model-written summary
IAA accumulates in cereal plants during early Fusarium graminearum infection.
- Taxon
- cereal plantse0
- Interactor
- Fusarium graminearum
Fusarium graminearume0pathogen - Outcome
- Indole-3-acetic acid (IAA)e0
- Direction
- extensive accumulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_on_Corn_(Zea_mays)_at_Waimea%2C_Hawaii.jpg?width=500)
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”
Claim · model-written summary
IAA has been suggested as a virulence factor that alters host nutrition and immunity.
- Taxon
- cerealst0
- Interactor
- Fusarium graminearum
Fusarium 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.
_on_Corn_(Zea_mays)_at_Waimea%2C_Hawaii.jpg?width=500)
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”
t0“cereals after infection by Fusarium graminearum”
Claim · model-written summary
Plant and fungal genomes are predicted to contain genes for L-tryptophan-dependent IAA biosynthesis.
- Taxon
- cerealst0
- Interactor
- Fusarium graminearum
Fusarium 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.
_on_Corn_(Zea_mays)_at_Waimea%2C_Hawaii.jpg?width=500)
Verbatim
e0“Plant and fungus genomic studies have predicted that their genomes carry the required genes for L-tryptophan-dependent IAA biosynthetic pathways”
t0“cereals after infection by Fusarium graminearum”
Claim · model-written summary
F. graminearum infection may preferentially trigger conversion of L-TRP to serotonin and phytomelatonin in wheat heads.
- Taxon
- wheat
Triticum aestivume0 - Organ / stage
- wheat headse0
- Interactor
- F. graminearum
Fusarium 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.

_on_Corn_(Zea_mays)_at_Waimea%2C_Hawaii.jpg?width=500)
Verbatim
e0“infection by F. graminearum could preferentially trigger L-TRP's conversion into serotonin and even phytomelatonin via tryptamine in wheat heads”
Claim · model-written summary
Low concentrations of these metabolites have been reported to stimulate IAA accumulation.
- Taxon
- cerealst0
- Interactor
- Fusarium graminearum
Fusarium graminearumt0pathogen - Compound
- theme0
- Outcome
- IAA accumulatione0
- Direction
- stimulatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_on_Corn_(Zea_mays)_at_Waimea%2C_Hawaii.jpg?width=500)
Verbatim
e0“Lower concentrations of them have been shown to stimulate IAA accumulation or mimic IAA to promote plant growth”
t0“cereals after infection by Fusarium graminearum”
Claim · model-written summary
The authors recommend identifying fungal effectors involved in cereal IAA accumulation.
Verbatim
e0“ongoing efforts should focus more on identifying the fungal effectors involved in extensive IAA accumulation in cereals”