Abstract
Huanglongbing (HLB) is a devastating disease of citrus and threatens the citrus industry worldwide. The suspected causal agent of the disease is a phloem-limited bacterium of the genus Candidatus Liberibacter transmitted through insect vector or grafting with diseased budwood. Currently, most seed source trees for citrus rootstock propagation are located outdoors and unprotected from disease transmission. In addition, fruit from HLB-affected scion varieties in Florida containing seeds enter the commercial trade and move into other citrus-growing areas. The objective of this study was to determine how Ca . L. asiaticus infection affects seed quality and seedling development and whether the disease appears in seedlings grown from infected fruit. Two experiments were conducted involving thousands of seedlings produced from seeds from infected rootstock seed source trees and ‘Valencia’ sweet orange trees, respectively. Infection of trees and fruit with Ca . L. asiaticus significantly reduced seed weight, seed germination, and seedling height. Seedlings did not develop symptoms typical of HLB throughout the experiment. Polymerase chain reaction (PCR) analysis initially identified two of 686 rootstock seedlings and three of 431 sweet orange seedlings positive for the pathogen when they were very young. Resampling and PCR analysis of these five seedlings at older ages consistently indicated they were negative for the pathogen and none of these plants ever developed symptoms of HLB. It is suggested that Ca . L. asiaticus may have been translocated into some part of the embryo during seed development but that it was not present in cells or tissue, which permitted replication or disease development as the seedling grew.
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Claims 8
Claim · model-written summary
Ca . L. asiaticus infection significantly reduced citrus seed weight.
- Treatment
- Infection of trees and fruit with Ca . L. asiaticuse0
- Interactor
- Ca . L. asiaticuse0pathogen
- Outcome
- seed weighte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection of trees and fruit with Ca . L. asiaticus significantly reduced seed weight, seed germination, and seedling height.”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Ca . L. asiaticus infection significantly reduced citrus seed germination.
- Treatment
- Infection of trees and fruit with Ca . L. asiaticuse0
- Interactor
- Ca . L. asiaticuse0pathogen
- Outcome
- seed germinatione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection of trees and fruit with Ca . L. asiaticus significantly reduced seed weight, seed germination, and seedling height.”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Ca . L. asiaticus infection significantly reduced citrus seedling height.
- Treatment
- Infection of trees and fruit with Ca . L. asiaticuse0
- Interactor
- Ca . L. asiaticuse0pathogen
- Outcome
- seedling heighte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infection of trees and fruit with Ca . L. asiaticus significantly reduced seed weight, seed germination, and seedling height.”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Seedlings developed no typical HLB symptoms during the experiment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedlings did not develop symptoms typical of HLB throughout the experiment.”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Initial PCR found two of 686 rootstock seedlings positive for the pathogen.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Polymerase chain reaction (PCR) analysis initially identified two of 686 rootstock seedlings and three of 431 sweet orange seedlings positive for the pathogen”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Initial PCR found three of 431 sweet orange seedlings positive for the pathogen.
- Taxon
- sweet orange
Citrus sinensise0 - Organ / stage
- seedlingse0
- Outcome
- positive for the pathogene0
- Value
- three of 431e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Polymerase chain reaction (PCR) analysis initially identified two of 686 rootstock seedlings and three of 431 sweet orange seedlings positive for the pathogen”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
Later PCR tests consistently found all five initially positive seedlings negative for the pathogen.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Resampling and PCR analysis of these five seedlings at older ages consistently indicated they were negative for the pathogen”
t0“Citrus Seeds and Seedlings”
Claim · model-written summary
The authors suggested transient transfer of the bacterium into embryo parts without seedling replication or disease development.
- Interactor
- Ca . L. asiaticuse0pathogen
- Outcome
- translocated into some part of the embryoe0
- Qualifier
- not present in cells or tissuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ca . L. asiaticus may have been translocated into some part of the embryo during seed development but that it was not present in cells or tissue, which permitted replication or disease development as the seedling grew.”
t0“Citrus Seeds and Seedlings”
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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.