Abstract
Citrus canker, caused by Xanthomonas citri, affects most commercial citrus varieties. All X. citri strains possess at least one transcription activator-like effector of the PthA family that activates host disease susceptibility (S) genes. The X. citri strain 306 encodes four PthA effectors; nevertheless, only PthA4 is known to elicit cankers on citrus. As none of the PthAs act as avirulence factors on citrus, we hypothesized that PthAs 1-3 might also contribute to pathogenicity on certain hosts. Here, we show that, although PthA4 is indispensable for canker formation in six Brazilian citrus varieties, PthAs 1 and 3 contribute to canker development in 'Pera' sweet orange, but not in 'Tahiti' lemon. Deletions in two or more pthA genes reduce bacterial growth in planta more pronouncedly than single deletions, suggesting an additive role of PthAs in pathogenicity and bacterial fitness. The contribution of PthAs 1 and 3 in canker formation in 'Pera' plants does not correlate with the activation of the canker S gene, LOB1 (LATERAL ORGAN BOUNDARIES 1), but with the induction of other PthA targets, including LOB2 and citrus dioxygenase (DIOX). LOB1, LOB2 and DIOX show differential PthA-dependent expression between 'Pera' and 'Tahiti' plants that appears to be associated with nucleotide polymorphisms found at or near PthA-binding sites. We also present evidence that LOB1 activation alone is not sufficient to elicit cankers on citrus, and that DIOX acts as a canker S gene in 'Pera', but not 'Tahiti', plants. Our results suggest that the activation of multiple S genes, such as LOB1 and DIOX, is necessary for full canker development.
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Claims 12
Claim · model-written summary
PthA4 was indispensable for canker formation across six Brazilian citrus varieties.
- Interactor
- Xanthomonas citri
Xanthomonas citrit1pathogen - Gene
- PthA4e0
- Outcome
- canker formatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“although PthA4 is indispensable for canker formation in six Brazilian citrus varieties”
t1“Xanthomonas citri”
Claim · model-written summary
PthAs 1 and 3 contributed to canker development in Pera sweet orange.
- Taxon
- sweet orange
Citrus sinensise0 - Material
- 'Pera'e0
- Interactor
- Xanthomonas citriXanthomonas citrit1pathogen
- Gene
- PthAs 1 and 3e0
- Outcome
- canker developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PthAs 1 and 3 contribute to canker development in 'Pera' sweet orange”
t1“Xanthomonas citri”
Claim · model-written summary
PthAs 1 and 3 did not contribute to canker development in Tahiti lemon.
- Taxon
- lemon
Citrus ×limone0 - Material
- 'Tahiti'e0
- Interactor
- Xanthomonas citriXanthomonas citrit0pathogen
- Gene
- PthAs 1 and 3t1
- Outcome
- canker developmentt1
- Direction
- note0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not in 'Tahiti' lemon”
t1“PthAs 1 and 3 contribute to canker development in 'Pera' sweet orange”
t0“Xanthomonas citri”
Claim · model-written summary
Deleting two or more pthA genes reduced bacterial growth in planta more than single deletions.
- Treatment
- Deletions in two or more pthA genese0
- Interactor
- Xanthomonas citriXanthomonas citrit1pathogen
- Gene
- pthA genese0
- Outcome
- bacterial growth in plantae0
- Direction
- reducee0
- Comparator
- single deletionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Deletions in two or more pthA genes reduce bacterial growth in planta more pronouncedly than single deletions”
t0“citrus”
t1“Xanthomonas citri”
Claim · model-written summary
PthA1 and PthA3 contributions to Pera cankers did not correlate with LOB1 activation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The contribution of PthAs 1 and 3 in canker formation in 'Pera' plants does not correlate with the activation of the canker S gene, LOB1”
t0“citrus”
Claim · model-written summary
PthA1 and PthA3 contributions to Pera cankers correlated with induction of LOB2 and DIOX.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but with the induction of other PthA targets, including LOB2 and citrus dioxygenase (DIOX)”
t1“The contribution of PthAs 1 and 3 in canker formation in 'Pera' plants”
Claim · model-written summary
LOB1, LOB2, and DIOX expression differed between Pera and Tahiti plants with PthA dependence.
- Material
- 'Pera'e0
- Gene
- LOB1, LOB2 and DIOXe0
- Outcome
- PthA-dependent expressione0
- Direction
- differentiale0
- Comparator
- 'Tahiti'e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LOB1, LOB2 and DIOX show differential PthA-dependent expression between 'Pera' and 'Tahiti' plants”
t0“citrus”
Claim · model-written summary
PthA-dependent expression differences appeared associated with nucleotide polymorphisms near PthA-binding sites.
- Gene
- PthA-binding sitese0
- Outcome
- PthA-dependent expressiont1
- Qualifier
- nucleotide polymorphisms found at or near PthA-binding sitese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“appears to be associated with nucleotide polymorphisms found at or near PthA-binding sites”
t0“citrus”
t1“PthA-dependent expression”
Claim · model-written summary
LOB1 activation alone was insufficient to cause citrus cankers.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LOB1 activation alone is not sufficient to elicit cankers on citrus”
Claim · model-written summary
DIOX acted as a canker susceptibility gene in Pera plants.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DIOX acts as a canker S gene in 'Pera'”
t0“citrus”
Claim · model-written summary
DIOX did not act as a canker susceptibility gene in Tahiti plants.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not 'Tahiti', plants”
t0“citrus”
t1“DIOX acts as a canker S gene in 'Pera'”
Claim · model-written summary
The authors infer that activation of multiple susceptibility genes is needed for full canker development.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activation of multiple S genes, such as LOB1 and DIOX, is necessary for full canker development”
t0“citrus”
The same questions in other papers
loss of function · Xanthomonas citri · CitrusPositive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- negative
- no effect
- positive
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.