Abstract
BACKGROUND: Naphthaleneacetic acid (NAA), a synthetic auxin analogue, is widely used as an effective thinner in apple orchards. When applied shortly after fruit set, some fruit abscise leading to improved fruit size and quality. However, the thinning results of NAA are inconsistent and difficult to predict, sometimes leading to excess fruit drop or insufficient thinning which are costly to growers. This unpredictability reflects our incomplete understanding of the mode of action of NAA in promoting fruit abscission. RESULTS: Here we compared NAA-induced fruit drop with that caused by shading via gene expression profiling performed on the fruit abscission zone (FAZ), sampled 1, 3, and 5 d after treatment. More than 700 genes with significant changes in transcript abundance were identified from NAA-treated FAZ. Combining results from both treatments, we found that genes associated with photosynthesis, cell cycle and membrane/cellular trafficking were downregulated. On the other hand, there was up-regulation of genes related to ABA, ethylene biosynthesis and signaling, cell wall degradation and programmed cell death. While the differentially expressed gene sets for NAA and shading treatments shared only 25% identity, NAA and shading showed substantial similarity with respect to the classes of genes identified. Specifically, photosynthesis, carbon utilization, ABA and ethylene pathways were affected in both NAA- and shading-induced young fruit abscission. Moreover, we found that NAA, similar to shading, directly interfered with leaf photosynthesis by repressing photosystem II (PSII) efficiency within 10 minutes of treatment, suggesting that NAA and shading induced some of the same early responses due to reduced photosynthesis, which concurred with changes in hormone signaling pathways and triggered fruit abscission. CONCLUSIONS: This study provides an extensive transcriptome study and a good platform for further investigation of possible regulatory genes involved in the induction of young fruit abscission in apple, which will enable us to better understand the mechanism of fruit thinning and facilitate the selection of potential chemicals for the thinning programs in apple.
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Claims 8
Claim · model-written summary
NAA treatment changed abundance of more than 700 FAZ transcripts.
- Taxon
- apple
Malus domesticat0 - Organ / stage
- FAZe0
- Treatment
- NAA-treatede0
- Outcome
- transcript abundancee0
- Value
- More than 700 genese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“More than 700 genes with significant changes in transcript abundance were identified from NAA-treated FAZ”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA and shading downregulated photosynthesis, cell-cycle and membrane or cellular-trafficking genes in apple fruit abscission zones.
- Taxon
- appleMalus domesticat0
- Treatment
- both treatmentse1
- Outcome
- genes associated with photosynthesis, cell cycle and membrane/cellular traffickinge0
- Direction
- downregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“genes associated with photosynthesis, cell cycle and membrane/cellular trafficking were downregulated”
e1“both treatments”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA and shading upregulated genes related to ABA, ethylene, cell-wall degradation and programmed cell death.
- Taxon
- appleMalus domesticat0
- Treatment
- both treatmentse1
- Outcome
- genes related to ABA, ethylene biosynthesis and signaling, cell wall degradation and programmed cell deathe0
- Direction
- up-regulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“up-regulation of genes related to ABA, ethylene biosynthesis and signaling, cell wall degradation and programmed cell death”
e1“both treatments”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA and shading differential gene sets shared 25% identity.
- Taxon
- appleMalus domesticat0
- Outcome
- identitye0
- Value
- 25%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the differentially expressed gene sets for NAA and shading treatments shared only 25% identity”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA and shading affected similar classes of genes.
- Taxon
- appleMalus domesticat0
- Outcome
- substantial similarity with respect to the classes of genes identifiede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NAA and shading showed substantial similarity with respect to the classes of genes identified”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA and shading affected photosynthesis, carbon utilization, ABA and ethylene pathways during apple fruit abscission.
- Taxon
- appleMalus domesticat0
- Organ / stage
- young fruite0
- Outcome
- photosynthesis, carbon utilization, ABA and ethylene pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photosynthesis, carbon utilization, ABA and ethylene pathways were affected in both NAA- and shading-induced young fruit abscission”
t0“apple (Malus domestica)”
Claim · model-written summary
NAA rapidly repressed leaf PSII efficiency.
- Taxon
- appleMalus domesticat0
- Organ / stage
- leafe0
- Treatment
- NAAe0
- Outcome
- photosystem II (PSII) efficiencye0
- Direction
- repressinge0
- Qualifier
- within 10 minutes of treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NAA, similar to shading, directly interfered with leaf photosynthesis by repressing photosystem II (PSII) efficiency within 10 minutes of treatment”
t0“apple (Malus domestica)”
Claim · model-written summary
The authors infer reduced photosynthesis and hormone-signaling changes contributed to fruit abscission after NAA and shading.
- Taxon
- appleMalus domesticat0
- Outcome
- fruit abscissione0
- Qualifier
- reduced photosynthesis, which concurred with changes in hormone signaling pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced photosynthesis, which concurred with changes in hormone signaling pathways and triggered fruit abscission”
t0“apple (Malus domestica)”
The same questions in other papers
1-naphthaleneacetic acid · physiology: photosynthesis · Malus domestica (apple)Results agree
2 papers in the same direction as this paper
- 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.