Abstract
Caleosins (CLOs) or peroxygenases (PXGs), a class of structural proteins of lipid droplets (LDs), comprise a small family of multifunctional proteins widely involved in oil accumulation, organ development, and stress responses. Despite the proposal of two clades termed H and L in Arabidopsis thaliana, their evolution in the order Brassicales has not been well established. In this study, the first genome-wide analysis of the caleosin family was conducted in papaya (Carica papaya), a Caricaceae plant without any recent whole-genome duplication (WGD). A high number of five members representing both H and L clades were identified from the papaya genome. Further identification and comparison of 68 caleosin genes from 14 representative plant species revealed seven orthogroups, i.e., H1–4 and L1–3, where H1 and L1 have already appeared in the basal angiosperm Amborella trichopoda, supporting their early divergence before angiosperm radiation. Five CpCLO genes belong to H1 (1) and L1 (4), and extensive expansion of the L1 group was shown to be contributed to by species-specific tandem and transposed duplications, which may contribute to environmental adaptation. Orthologous and syntenic analyses uncovered that lineage-specific expansion of the caleosin family in Brassicales relative to A. trichopoda was largely contributed to by tandem duplication and recent WGDs, as well as the ancient γ whole-genome triplication (WGT) shared by all core eudicots. Independent gain or loss of certain introns and apparent expression divergence of caleosin genes were also observed. Tissue-specific expression analysis showed that CpCLO2 and −5 are constitutively expressed, whereas others appear to be tissue-specific, implying function divergence. Interestingly, the H-forms CpCLO1 and RcCLO1 were shown to exhibit similar expression profiles to most oleosin genes that are preferentially expressed oil-rich tissues such as seeds/endosperms, shoots, and calluses, implying their putative involvement in oil accumulation, as observed in Arabidopsis. The results obtained from this study provide a global view of CpCLO genes and insights into lineage-specific family evolution in Brassicales, which facilitates further functional studies in papaya and other non-model species.
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Claims 11
Claim · model-written summary
Five caleosin genes are identified from the papaya genome.
- Taxon
- papaya
_-_DPLA_-_55200ec009622d7d42349f3583df310e.jpg?width=60)
Carica papayae1 - Outcome
- members representing both H and L cladese1
- Value
- fivee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_-_DPLA_-_55200ec009622d7d42349f3583df310e.jpg?width=500)
Verbatim
e1“A high number of five members representing both H and L clades were identified from the papaya genome”
Claim · model-written summary
Caleosin genes from 14 representative plant species form seven orthogroups, H1–4 and L1–3.
Verbatim
e2“Further identification and comparison of 68 caleosin genes from 14 representative plant species revealed seven orthogroups, i.e., H1–4 and L1–3”
Claim · model-written summary
H1 and L1 caleosin orthogroups already appear in Amborella trichopoda, supporting early divergence before angiosperm radiation.
- Taxon
- Amborella trichopoda
Amborella trichopodae3 - Outcome
- H1 and L1e3
- Qualifier
- early divergence before angiosperm radiatione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“H1 and L1 have already appeared in the basal angiosperm Amborella trichopoda, supporting their early divergence before angiosperm radiation”
Claim · model-written summary
Five CpCLO genes belong to H1 (1) and L1 (4).
- Taxon
- Carica papayaCarica papayat0
- Gene
- CpCLOe4
- Outcome
- belong to H1 (1) and L1 (4)e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e4“Five CpCLO genes belong to H1 (1) and L1 (4)”
Claim · model-written summary
Expansion of the L1 group is contributed to by species-specific tandem and transposed duplications.
- Taxon
- Carica papayaCarica papayat0
- Outcome
- expansion of the L1 groupe5
- Qualifier
- species-specific tandem and transposed duplicationse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e5“extensive expansion of the L1 group was shown to be contributed to by species-specific tandem and transposed duplications, which may contribute to environmental adaptation”
Claim · model-written summary
Lineage-specific expansion of the caleosin family in Brassicales relative to Amborella trichopoda is largely contributed to by tandem duplication, recent WGDs and the ancient γ whole-genome triplication.
- Taxon
- BrassicalesBrassicalese6
- Outcome
- lineage-specific expansion of the caleosin family in Brassicalese6
- Qualifier
- tandem duplication and recent WGDs, as well as the ancient γ whole-genome triplication (WGT)e6
Verbatim
e6“lineage-specific expansion of the caleosin family in Brassicales relative to A. trichopoda was largely contributed to by tandem duplication and recent WGDs, as well as the ancient γ whole-genome triplication (WGT) shared by all core eudicots”
Claim · model-written summary
Independent gain or loss of certain introns and apparent expression divergence of caleosin genes are observed.
- Taxon
- Carica papayaCarica papayat0
- Outcome
- gain or loss of certain introns and apparent expression divergencee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e7“Independent gain or loss of certain introns and apparent expression divergence of caleosin genes were also observed”
Claim · model-written summary
CpCLO2 and CpCLO5 are constitutively expressed across tissues.
- Taxon
- Carica papayaCarica papayat0
- Gene
- CpCLO2 and −5e6
- Outcome
- constitutively expressede6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e6“Tissue-specific expression analysis showed that CpCLO2 and −5 are constitutively expressed”
Claim · model-written summary
Other caleosin genes appear to be tissue-specific, implying function divergence.
- Taxon
- Carica papayaCarica papayat0
- Outcome
- appear to be tissue-specifice7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e7“whereas others appear to be tissue-specific, implying function divergence”
Claim · model-written summary
H-form CpCLO1 and RcCLO1 show expression profiles similar to most oleosin genes, which are expressed preferentially in seeds/endosperms, shoots and calluses.
- Taxon
- Carica papayaCarica papayat0
- Organ / stage
- seeds/endosperms, shoots, and callusese6
- Gene
- CpCLO1 and RcCLO1e6
- Outcome
- expression profilese6
- Direction
- similare6
- Comparator
- most oleosin genese6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e6“H-forms CpCLO1 and RcCLO1 were shown to exhibit similar expression profiles to most oleosin genes that are preferentially expressed oil-rich tissues such as seeds/endosperms, shoots, and calluses”
Claim · model-written summary
CpCLO1 and RcCLO1 are putatively involved in oil accumulation.
- Taxon
- Carica papayaCarica papayat0
- Gene
- CpCLO1 and RcCLO1e6
- Outcome
- oil accumulatione7
- Qualifier
- putative involvemente7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Characterization of Caleosin Genes in Carica papaya”
e6“H-forms CpCLO1 and RcCLO1 were shown to exhibit similar expression profiles to most oleosin genes that are preferentially expressed oil-rich tissues such as seeds/endosperms, shoots, and calluses”
e7“implying their putative involvement in oil accumulation, as observed in Arabidopsis”