Abstract
BACKGROUND AND AIMS: Many gymnosperms produce an ovular secretion, the pollination drop, during reproduction. The drops serve as a landing site for pollen, but also contain a suite of ions and organic compounds, including proteins, that suggests diverse roles for the drop during pollination. Proteins in the drops of species of Chamaecyparis, Juniperus, Taxus, Pseudotsuga, Ephedra and Welwitschia are thought to function in the conversion of sugars, defence against pathogens, and pollen growth and development. To better understand gymnosperm pollination biology, the pollination drop proteomes of pollination drops from two species of Cephalotaxus have been characterized and an ovular transcriptome for C. sinensis has been assembled. METHODS: Mass spectrometry was used to identify proteins in the pollination drops of Cephalotaxus sinensis and C. koreana RNA-sequencing (RNA-Seq) was employed to assemble a transcriptome and identify transcripts present in the ovules of C. sinensis at the time of pollination drop production. KEY RESULTS: About 30 proteins were detected in the pollination drops of both species. Many of these have been detected in the drops of other gymnosperms and probably function in defence, polysaccharide metabolism and pollen tube growth. Other proteins appear to be unique to Cephalotaxus, and their putative functions include starch and callose degradation, among others. Together, the proteins appear either to have been secreted into the drop or to occur there due to breakdown of ovular cells during drop production. Ovular transcripts represent a wide range of gene ontology categories, and some may be involved in drop formation, ovule development and pollen-ovule interactions. CONCLUSIONS: The proteome of Cephalotaxus pollination drops shares a number of components with those of other conifers and gnetophytes, including proteins for defence such as chitinases and for carbohydrate modification such as β-galactosidase. Proteins likely to be of intracellular origin, however, form a larger component of drops from Cephalotaxus than expected from studies of other conifers. This is consistent with the observation of nucellar breakdown during drop formation in Cephalotaxus The transcriptome data provide a framework for understanding multiple metabolic processes that occur within the ovule and the pollination drop just before fertilization. They reveal the deep conservation of WUSCHEL expression in ovules and raise questions about whether any of the S-locus transcripts in Cephalotaxus ovules might be involved in pollen-ovule recognition.
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Claims 9
Claim · model-written summary
About 30 proteins were found in pollination drops of both Cephalotaxus species.
- Taxon
- Cephalotaxus sinensis
Cephalotaxus sinensise1 - Organ / stage
- pollination dropse0
- Outcome
- proteins were detected in the pollination dropse0
- Value
- About 30 proteinse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“About 30 proteins were detected in the pollination drops of both species.”
e1“pollination drops of Cephalotaxus sinensis and C. koreana”
Claim · model-written summary
Some drop proteins appear unique to Cephalotaxus and may degrade starch and callose.
- Taxon
- Cephalotaxus
Cephalotaxuse0 - Outcome
- proteins appear to be uniquee0
- Qualifier
- putative functions include starch and callose degradatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Other proteins appear to be unique to Cephalotaxus, and their putative functions include starch and callose degradation, among others.”
Claim · model-written summary
Pollination drop proteins appear either secreted or released through ovular cell breakdown.
- Taxon
- CephalotaxusCephalotaxuse1
- Outcome
- proteins appear either to have been secreted into the drop or to occur theree0
- Qualifier
- breakdown of ovular cells during drop productione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Together, the proteins appear either to have been secreted into the drop or to occur there due to breakdown of ovular cells during drop production.”
e1“Cephalotaxus pollination drops”
Claim · model-written summary
Ovular transcripts spanned many gene ontology categories and some may contribute to drop formation, ovule development and pollen-ovule interactions.
- Taxon
- CephalotaxusCephalotaxuse1
- Organ / stage
- Ovulare0
- Outcome
- Ovular transcripts represent a wide range of gene ontology categoriese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ovular transcripts represent a wide range of gene ontology categories, and some may be involved in drop formation, ovule development and pollen-ovule interactions.”
e1“Cephalotaxus pollination drops”
Claim · model-written summary
Cephalotaxus drop proteomes share defense and carbohydrate modification components with other conifers and gnetophytes.
- Taxon
- CephalotaxusCephalotaxuse0
- Gene
- chitinasese0
- Outcome
- shares a number of componentse0
- Comparator
- other conifers and gnetophytese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The proteome of Cephalotaxus pollination drops shares a number of components with those of other conifers and gnetophytes, including proteins for defence such as chitinases and for carbohydrate modification such as β-galactosidase.”
Claim · model-written summary
Likely intracellular proteins constitute a larger component of Cephalotaxus drops than expected from other conifers.
- Taxon
- CephalotaxusCephalotaxuse0
- Outcome
- Proteins likely to be of intracellular origine0
- Direction
- largere0
- Comparator
- other coniferse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Proteins likely to be of intracellular origin, however, form a larger component of drops from Cephalotaxus than expected from studies of other conifers.”
Claim · model-written summary
Nucellar breakdown was observed during Cephalotaxus drop formation.
- Taxon
- CephalotaxusCephalotaxuse0
- Organ / stage
- nucellare0
- Outcome
- nucellar breakdown during drop formatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“observation of nucellar breakdown during drop formation in Cephalotaxus”
Claim · model-written summary
Transcriptome data reveal conserved WUSCHEL expression in ovules.
- Taxon
- CephalotaxusCephalotaxuse1
- Organ / stage
- ovulese0
- Gene
- WUSCHELe0
- Outcome
- deep conservation of WUSCHEL expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They reveal the deep conservation of WUSCHEL expression in ovules”
e1“Cephalotaxus ovules”
Claim · model-written summary
The Cephalotaxus transcriptome provides a framework for studying metabolism in ovules and pollination drops.
- Taxon
- CephalotaxusCephalotaxuse1
- Organ / stage
- ovulee0
- Outcome
- framework for understanding multiple metabolic processese0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The transcriptome data provide a framework for understanding multiple metabolic processes that occur within the ovule and the pollination drop just before fertilization.”
e1“Cephalotaxus ovules”