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Conservation of the abscission signaling peptide IDA during Angiosperm evolution: withstanding genome duplications and gain and loss of the receptors HAE/HSL2.

Stø IM, Orr RJ, Fooyontphanich K, Jin X, Knutsen JM, Fischer U, Tranbarger TJ, Nordal I, Aalen RB - Front Plant Sci (2015)

Bottom Line: Genes encoding IDA or IDA-LIKE (IDL) peptides and HSL proteins were found in all investigated species, which were selected as to represent each angiosperm order with available genomic sequences.IDA has been duplicated in eudicots to give rise to functionally divergent IDL peptides.We postulate that the high number of IDL homologs present in the core eudicots is a result of multiple whole genome duplications (WGD).

View Article: PubMed Central - PubMed

Affiliation: Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo Oslo, Norway.

ABSTRACT
The peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which signals through the leucine-rich repeat receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2), controls different cell separation events in Arabidopsis thaliana. We hypothesize the involvement of this signaling module in abscission processes in other plant species even though they may shed other organs than A. thaliana. As the first step toward testing this hypothesis from an evolutionarily perspective we have identified genes encoding putative orthologs of IDA and its receptors by BLAST searches of publically available protein, nucleotide and genome databases for angiosperms. Genes encoding IDA or IDA-LIKE (IDL) peptides and HSL proteins were found in all investigated species, which were selected as to represent each angiosperm order with available genomic sequences. The 12 amino acids representing the bioactive peptide in A. thaliana have virtually been unchanged throughout the evolution of the angiosperms; however, the number of IDL and HSL genes varies between different orders and species. The phylogenetic analyses suggest that IDA, HSL2, and the related HSL1 gene, were present in the species that gave rise to the angiosperms. HAE has arisen from HSL1 after a genome duplication that took place after the monocot-eudicots split. HSL1 has also independently been duplicated in the monocots, while HSL2 has been lost in gingers (Zingiberales) and grasses (Poales). IDA has been duplicated in eudicots to give rise to functionally divergent IDL peptides. We postulate that the high number of IDL homologs present in the core eudicots is a result of multiple whole genome duplications (WGD). We substantiate the involvement of IDA and HAE/HSL2 homologs in abscission by providing gene expression data of different organ separation events from various species.

No MeSH data available.


Related in: MedlinePlus

Expression of HAE and HSL2 promoter: GUS constructs at sites of ectopic abscission. (A–C) Enlargement of AZ and premature abscission of whole flowers and immature fruits compared to wild type silique (to the left in A) in A. thaliana plants overexpressing AtIDL1. (D) Enlarged vestigial AZ after abscission of a cauline leaf in A. thaliana overexpressing AtIDL1. (E,F)pHAE:GUS expression and (G)pHSL2:GUS expression in vestigial AZs at the bases of pedicels, branches, and cauline leaves.
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Figure 4: Expression of HAE and HSL2 promoter: GUS constructs at sites of ectopic abscission. (A–C) Enlargement of AZ and premature abscission of whole flowers and immature fruits compared to wild type silique (to the left in A) in A. thaliana plants overexpressing AtIDL1. (D) Enlarged vestigial AZ after abscission of a cauline leaf in A. thaliana overexpressing AtIDL1. (E,F)pHAE:GUS expression and (G)pHSL2:GUS expression in vestigial AZs at the bases of pedicels, branches, and cauline leaves.

Mentions: Normally A. thaliana does not shed cauline leaves, whole flowers or fruits. However, ectopic expression of IDA and IDL peptides in A. thaliana leads to induction of abscission in a HAE/HSL2-dependent manner at the base of pedicels, cauline leaves, and inflorescence branches, rather than a general separation of cells in the plant (Figures 4A–D) (Stenvik et al., 2006). These are sites of abscission in other species. Interestingly, A. thaliana lines transformed with promoter:GUS constructs for HAE or HSL2 show that the receptor genes are expressed in the vestigial AZs at these sites (Figures 4E–G).


Conservation of the abscission signaling peptide IDA during Angiosperm evolution: withstanding genome duplications and gain and loss of the receptors HAE/HSL2.

Stø IM, Orr RJ, Fooyontphanich K, Jin X, Knutsen JM, Fischer U, Tranbarger TJ, Nordal I, Aalen RB - Front Plant Sci (2015)

Expression of HAE and HSL2 promoter: GUS constructs at sites of ectopic abscission. (A–C) Enlargement of AZ and premature abscission of whole flowers and immature fruits compared to wild type silique (to the left in A) in A. thaliana plants overexpressing AtIDL1. (D) Enlarged vestigial AZ after abscission of a cauline leaf in A. thaliana overexpressing AtIDL1. (E,F)pHAE:GUS expression and (G)pHSL2:GUS expression in vestigial AZs at the bases of pedicels, branches, and cauline leaves.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4627355&req=5

Figure 4: Expression of HAE and HSL2 promoter: GUS constructs at sites of ectopic abscission. (A–C) Enlargement of AZ and premature abscission of whole flowers and immature fruits compared to wild type silique (to the left in A) in A. thaliana plants overexpressing AtIDL1. (D) Enlarged vestigial AZ after abscission of a cauline leaf in A. thaliana overexpressing AtIDL1. (E,F)pHAE:GUS expression and (G)pHSL2:GUS expression in vestigial AZs at the bases of pedicels, branches, and cauline leaves.
Mentions: Normally A. thaliana does not shed cauline leaves, whole flowers or fruits. However, ectopic expression of IDA and IDL peptides in A. thaliana leads to induction of abscission in a HAE/HSL2-dependent manner at the base of pedicels, cauline leaves, and inflorescence branches, rather than a general separation of cells in the plant (Figures 4A–D) (Stenvik et al., 2006). These are sites of abscission in other species. Interestingly, A. thaliana lines transformed with promoter:GUS constructs for HAE or HSL2 show that the receptor genes are expressed in the vestigial AZs at these sites (Figures 4E–G).

Bottom Line: Genes encoding IDA or IDA-LIKE (IDL) peptides and HSL proteins were found in all investigated species, which were selected as to represent each angiosperm order with available genomic sequences.IDA has been duplicated in eudicots to give rise to functionally divergent IDL peptides.We postulate that the high number of IDL homologs present in the core eudicots is a result of multiple whole genome duplications (WGD).

View Article: PubMed Central - PubMed

Affiliation: Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo Oslo, Norway.

ABSTRACT
The peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which signals through the leucine-rich repeat receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2), controls different cell separation events in Arabidopsis thaliana. We hypothesize the involvement of this signaling module in abscission processes in other plant species even though they may shed other organs than A. thaliana. As the first step toward testing this hypothesis from an evolutionarily perspective we have identified genes encoding putative orthologs of IDA and its receptors by BLAST searches of publically available protein, nucleotide and genome databases for angiosperms. Genes encoding IDA or IDA-LIKE (IDL) peptides and HSL proteins were found in all investigated species, which were selected as to represent each angiosperm order with available genomic sequences. The 12 amino acids representing the bioactive peptide in A. thaliana have virtually been unchanged throughout the evolution of the angiosperms; however, the number of IDL and HSL genes varies between different orders and species. The phylogenetic analyses suggest that IDA, HSL2, and the related HSL1 gene, were present in the species that gave rise to the angiosperms. HAE has arisen from HSL1 after a genome duplication that took place after the monocot-eudicots split. HSL1 has also independently been duplicated in the monocots, while HSL2 has been lost in gingers (Zingiberales) and grasses (Poales). IDA has been duplicated in eudicots to give rise to functionally divergent IDL peptides. We postulate that the high number of IDL homologs present in the core eudicots is a result of multiple whole genome duplications (WGD). We substantiate the involvement of IDA and HAE/HSL2 homologs in abscission by providing gene expression data of different organ separation events from various species.

No MeSH data available.


Related in: MedlinePlus