Abstract
Pseudocercosporella capsellae, the causative agent of white leaf spot disease in Brassicaceae, can produce a purple-pink pigment on artificial media resembling, but not previously confirmed as, the toxin cercosporin. Chemical extraction with ethyl acetate from growing hyphae followed by quantitative (thin-layer chromatography [TLC] and high-performance liquid chromatography [HPLC]) and qualitative methods showed an identical absorption spectrum, with similar retardation factor (Rf) values on TLC papers and an identical peak with the same retention time in HPLC as for a standard for cercosporin. We believe this is the first report to confirm that the purple-pink pigment produced by P. capsellae is cercosporin. Confocal microscopy detected green autofluorescence of cercosporin-producing hyphae, confirming the presence of cercosporin inside hyphae. The highly virulent UWA Wlra-7 isolate of P. capsellae produced the greatest quantity of cercosporin (10.69 mg g −1 ). The phytotoxicity and role of cercosporin in disease initiation across each of three Brassicaceae host species (Brassica juncea, B. napus, and Raphanus raphanistrum) was also studied. Culture filtrates containing cercosporin were phytotoxic to all three host plant species, producing large, white lesions on highly sensitive B. juncea, only water-soaked areas on least sensitive R. raphanistrum, and intermediate lesions on B. napus. It is noteworthy that sensitivity to cercosporin of these three host species was analogous to their susceptibility to the pathogen, viz., B. juncea the most susceptible, R. raphanistrum the least susceptible, and B. napus intermediate. The presence of cercosporin in the inoculum significantly increased disease severity on the highly cercosporin-sensitive B. juncea. We believe that this is the first study to demonstrate that P. capsellae produces cercosporin in liquid culture rather than agar media. Finally, this study highlights an important role of cercosporin as a pathogenicity factor in white leaf spot disease on Brassicaceae as evidenced by the ability of the cercosporin-rich culture filtrate to reproduce white leaf spot lesions on host plants and by the enhanced virulence of P. capsellae in the presence of cercosporin.
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Claims 5
Claim · model-written summary
Cercosporin-containing culture filtrates produced large, white lesions on B. juncea.
- Taxon
- B. juncea
Brassica junceae0 - Treatment
- Culture filtrates containing cercosporine0
- Outcome
- large, white lesionse0
Not reportedInteractorComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Culture filtrates containing cercosporin were phytotoxic to all three host plant species, producing large, white lesions on highly sensitive B. juncea, only water-soaked areas on least sensitive R. raphanistrum, and intermediate lesions on B. napus.”
Claim · model-written summary
Cercosporin-containing culture filtrates produced water-soaked areas on R. raphanistrum.
- Taxon
- R. raphanistrum
_Raphanus_raphanistrum_-_flowers.jpg?width=60)
Raphanus raphanistrume0 - Treatment
- Culture filtrates containing cercosporine0
- Outcome
- water-soaked arease0
Not reportedInteractorComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Raphanus_raphanistrum_-_flowers.jpg?width=500)
Verbatim
e0“Culture filtrates containing cercosporin were phytotoxic to all three host plant species, producing large, white lesions on highly sensitive B. juncea, only water-soaked areas on least sensitive R. raphanistrum, and intermediate lesions on B. napus.”
Claim · model-written summary
Cercosporin-containing culture filtrates produced intermediate lesions on B. napus.
- Taxon
- B. napus
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse0 - Treatment
- Culture filtrates containing cercosporine0
- Outcome
- intermediate lesionse0
Not reportedInteractorComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“Culture filtrates containing cercosporin were phytotoxic to all three host plant species, producing large, white lesions on highly sensitive B. juncea, only water-soaked areas on least sensitive R. raphanistrum, and intermediate lesions on B. napus.”
Claim · model-written summary
Cercosporin in the inoculum significantly increased disease severity on B. juncea.
- Taxon
- B. junceaBrassica junceae0
- Treatment
- presence of cercosporin in the inoculume0
- Outcome
- disease severitye0
- Direction
- increasede0
- Qualifier
- highly cercosporin-sensitivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The presence of cercosporin in the inoculum significantly increased disease severity on the highly cercosporin-sensitive B. juncea.”
Claim · model-written summary
Host sensitivity to cercosporin tracked susceptibility to the pathogen across the three host species.
- Taxon
- these three host speciese0
- Outcome
- sensitivity to cercosporine0
- Qualifier
- B. juncea the most susceptible, R. raphanistrum the least susceptible, and B. napus intermediatee0
- Comparator
- susceptibility to the pathogene0
Not reportedDirection
Verbatim
e0“It is noteworthy that sensitivity to cercosporin of these three host species was analogous to their susceptibility to the pathogen, viz., B. juncea the most susceptible, R. raphanistrum the least susceptible, and B. napus intermediate.”
The same questions in other papers
pathogen product · disease · Brassica napus (oilseed rape)Positive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
1 paper more in this group
See all 5 papers →inoculation · disease · Brassica juncea (Indian mustard)Results agree
3 papers in the same direction as this paper
- negative
- negative
- negative
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.