Abstract
‘Candidatus Liberibacter asiaticus’ is the bacterium associated with the citrus disease known as huanglongbing (HLB). This study evaluated the influence of ‘Ca. L. asiaticus’ infection on a number of key plant physiological variables concerning photosynthesis, cell integrity, reactive oxygen species scavengers’ activity, and osmoregulation of two different species of citrus—the pomelo Citrus maxima and the mandarin C. reticulata ‘Tankan’—relative to their measured ‘Ca. L. asiaticus’ infection load. Results indicated that all measured physiological variables except soluble sugar were affected by increased ‘Ca. L. asiaticus’ infection titers, wherein the variety C. maxima proved overall more resistant than C. reticulata. ‘Ca. L. asiaticus’ infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde, as well as increased free proline and starch contents. Chlorophyll fluorescence measurements taken 9 months after grafting the mandarin C. reticulata with ‘Ca. L. asiaticus’ scions revealed a significant decrease in the photosynthesis variables maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae, whereas nonphotochemical fluorescence quenching increased significantly; C. maxima plants, on the other hand, did not show significant differences until the 12th month from infection exposure. The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased and later decreased. In addition, progression of ‘Ca. L. asiaticus’ replication in both citrus species was accompanied by rapid changes in three reactive oxygen species scavenging enzymes in C. maxima, while the pattern was different in C. reticulata. We hypothesize that the observed interspecific differences in physiological change are related to their relative resistance against ‘Ca. L. asiaticus’ infection. These results provide a scaffold for better describing the pathogenesis, selecting the most resistant breeds, or even validating pertaining omics research; ultimately, these detailed observations can facilitate the diagnosis of ‘Ca. L. asiaticus’ infection.
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Claims 11
Claim · model-written summary
C. maxima was overall more resistant than C. reticulata.
- Taxon
- C. maxima
Citrus maximae0 - Interactor
- ‘Ca. L. asiaticus’e1pathogen
- Outcome
- resistante0
- Direction
- more resistante0
- Comparator
- C. reticulatae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“C. maxima proved overall more resistant than C. reticulata”
e1“all measured physiological variables except soluble sugar were affected by increased ‘Ca. L. asiaticus’ infection titers”
Claim · model-written summary
Soluble sugar was the exception to physiological variables affected by infection titers.
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all measured physiological variables except soluble sugar were affected by increased ‘Ca. L. asiaticus’ infection titers”
t0“Citrus Species”
Claim · model-written summary
Infection was linked to decreased chlorophyll concentration, cell membrane permeability, and malondialdehyde in both plants.
- Interactor
- ‘Ca. L. asiaticus’e0pathogen
- Outcome
- chlorophyll concentration, cell membrane permeability, and malondialdehydee0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“‘Ca. L. asiaticus’ infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde”
t0“Citrus Species”
Claim · model-written summary
Infection was linked to increased free proline and starch in both plants.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“‘Ca. L. asiaticus’ infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde, as well as increased free proline and starch contents”
t0“Citrus Species”
Claim · model-written summary
Mandarin PSII yield and photochemical quenching variables decreased significantly nine months after grafting.
- Taxon
- C. reticulata
.jpg?width=60)
Citrus reticulatae0 - Treatment
- ‘Ca. L. asiaticus’ scionse0
- Interactor
- ‘Ca. L. asiaticus’e0pathogen
- Outcome
- maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennaee0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“mandarin C. reticulata with ‘Ca. L. asiaticus’ scions revealed a significant decrease in the photosynthesis variables maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae”
Claim · model-written summary
Nonphotochemical fluorescence quenching increased significantly in mandarin after infection.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas nonphotochemical fluorescence quenching increased significantly”
t0“Citrus Species”
Claim · model-written summary
C. maxima showed no significant fluorescence differences until month 12 after exposure.
- Taxon
- C. maximaCitrus maximae0
- Outcome
- significant differencese0
- Qualifier
- until the 12th month from infection exposuree0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“C. maxima plants, on the other hand, did not show significant differences until the 12th month from infection exposure”
Claim · model-written summary
Superoxide dismutase, catalase, peroxidase, and soluble protein initially increased.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased”
t0“Citrus Species”
Claim · model-written summary
Superoxide dismutase, catalase, peroxidase, and soluble protein later decreased.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased and later decreased”
t0“Citrus Species”
Claim · model-written summary
Pathogen replication was accompanied by rapid changes in three scavenging enzymes in C. maxima.
- Taxon
- C. maximaCitrus maximae0
- Interactor
- ‘Ca. L. asiaticus’e0pathogen
- Outcome
- three reactive oxygen species scavenging enzymese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“progression of ‘Ca. L. asiaticus’ replication in both citrus species was accompanied by rapid changes in three reactive oxygen species scavenging enzymes in C. maxima”
Claim · model-written summary
The scavenging enzyme pattern differed in C. reticulata.
- Taxon
- C. reticulataCitrus reticulatae0
- Outcome
- the patterne0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while the pattern was different in C. reticulata”