Abstract
Mannitol has been hypothesized to play a role in antioxidant defense. In previous work, we confirmed the presence of the two mannitol biosynthetic enzymes, mannitol dehydrogenase (MtDH) and mannitol 1-phosphate 5-dehydrogenase (MPDH), in the fungus Alternaria alternata and created disruption mutants for both enzymes. These mutants were used to investigate the role of mannitol in pathogenicity of A. alternata on its host, tobacco. Conidia of all mutants were viable and germinated normally. GC-MS analysis demonstrated elevated levels of trehalose in the mutants, suggesting that trehalose may substitute for mannitol as a storage compound for germination. Tobacco inoculation showed no reduction in lesion severity caused by the MtDH mutant as compared with wild type; however, the MPDH mutant and a mutant in both enzymes caused significantly less disease. Microscopy analysis indicated that the double mutant was unaffected in the ability to germinate and produce appressoria on tobacco leaves and elicited a defense response from the host, indicating that it was able to penetrate and infect the host. We conclude that mannitol biosynthesis is required for pathogenesis of A. alternata on tobacco, but is not required for spore germination either in vitro or in planta or for initial infection.
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Claims 9
Claim · model-written summary
All fungal mutants produced viable conidia that germinated normally.
- Outcome
- Conidia of all mutants were viable and germinated normallye0
Not reportedTaxon
Verbatim
e0“Conidia of all mutants were viable and germinated normally”
Claim · model-written summary
Trehalose levels were elevated in the fungal mutants.
Not reportedTaxon
Verbatim
e0“GC-MS analysis demonstrated elevated levels of trehalose in the mutants”
Claim · model-written summary
The MtDH mutant did not reduce tobacco lesion severity versus wild type.
- Taxon
- Tobacco
Nicotiana tabacume0 - Treatment
- MtDH mutante0
- Gene
- MtDHe0
- Outcome
- lesion severitye0
- Direction
- no reductione0
- Comparator
- wild typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tobacco inoculation showed no reduction in lesion severity caused by the MtDH mutant as compared with wild type”
Claim · model-written summary
The MPDH mutant caused significantly less disease.
Not reportedTaxonComparator
Verbatim
e0“the MPDH mutant and a mutant in both enzymes caused significantly less disease”
Claim · model-written summary
The double mutant caused significantly less disease.
Not reportedTaxonComparator
Verbatim
e0“the MPDH mutant and a mutant in both enzymes caused significantly less disease”
Claim · model-written summary
The double mutant still germinated and formed appressoria on tobacco leaves.
- Taxon
- tobaccoNicotiana tabacume0
- Material
- double mutante0
- Organ / stage
- leavese0
- Outcome
- ability to germinate and produce appressoriae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the double mutant was unaffected in the ability to germinate and produce appressoria on tobacco leaves”
Claim · model-written summary
The double mutant elicited a host defense response.
- Outcome
- defense responsee0
Not reportedTaxon
Verbatim
e0“elicited a defense response from the host”
Claim · model-written summary
The authors conclude mannitol biosynthesis is required for A. alternata pathogenesis on tobacco.
- Taxon
- tobaccoNicotiana tabacume0
- Interactor
- A. alternata
.jpg?width=60)
Alternaria alternatae0pathogen - Outcome
- pathogenesis of A. alternatae0
- Qualifier
- mannitol biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“mannitol biosynthesis is required for pathogenesis of A. alternata on tobacco”
Claim · model-written summary
The authors conclude mannitol biosynthesis is not required for spore germination or initial infection.
Not reportedTaxon
Verbatim
e0“is not required for spore germination either in vitro or in planta or for initial infection”