Arabinogalactan proteins have deep roots in eukaryotes: identification of genes and epitopes in brown algae and their role in Fucus serratus embryo development

TY - JOUR

T1 - Arabinogalactan proteins have deep roots in eukaryotes

T2 - identification of genes and epitopes in brown algae and their role in Fucus serratus embryo development

AU - Hervé, Cécile

AU - Siméon, Amandine

AU - Jam, Murielle

AU - Cassin, Andrew

AU - Johnson, Kim L

AU - Asunción Salmeán, Armando

AU - Willats, William George Tycho

AU - Doblin, Monika S

AU - Bacic, Antony

AU - Kloareg, Bernard

N1 - © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

PY - 2016/3/1

Y1 - 2016/3/1

N2 - Arabinogalactan proteins (AGPs) are highly glycosylated, hydroxyproline-rich proteins found at the cell surface of plants, where they play key roles in developmental processes. Brown algae are marine, multicellular, photosynthetic eukaryotes. They belong to the phylum Stramenopiles, which is unrelated to land plants and green algae (Chloroplastida). Brown algae share common evolutionary features with other multicellular organisms, including a carbohydrate-rich cell wall. They differ markedly from plants in their cell wall composition, and AGPs have not been reported in brown algae. Here we investigated the presence of chimeric AGP-like core proteins in this lineage. We report that the genome sequence of the brown algal model Ectocarpus siliculosus encodes AGP protein backbone motifs, in a gene context that differs considerably from what is known in land plants. We showed the occurrence of AGP glycan epitopes in a range of brown algal cell wall extracts. We demonstrated that these chimeric AGP-like core proteins are developmentally regulated in embryos of the order Fucales and showed that AGP loss of function seriously impairs the course of early embryogenesis. Our findings shine a new light on the role of AGPs in cell wall sensing and raise questions about the origin and evolution of AGPs in eukaryotes.

AB - Arabinogalactan proteins (AGPs) are highly glycosylated, hydroxyproline-rich proteins found at the cell surface of plants, where they play key roles in developmental processes. Brown algae are marine, multicellular, photosynthetic eukaryotes. They belong to the phylum Stramenopiles, which is unrelated to land plants and green algae (Chloroplastida). Brown algae share common evolutionary features with other multicellular organisms, including a carbohydrate-rich cell wall. They differ markedly from plants in their cell wall composition, and AGPs have not been reported in brown algae. Here we investigated the presence of chimeric AGP-like core proteins in this lineage. We report that the genome sequence of the brown algal model Ectocarpus siliculosus encodes AGP protein backbone motifs, in a gene context that differs considerably from what is known in land plants. We showed the occurrence of AGP glycan epitopes in a range of brown algal cell wall extracts. We demonstrated that these chimeric AGP-like core proteins are developmentally regulated in embryos of the order Fucales and showed that AGP loss of function seriously impairs the course of early embryogenesis. Our findings shine a new light on the role of AGPs in cell wall sensing and raise questions about the origin and evolution of AGPs in eukaryotes.

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1111/nph.13786

DO - 10.1111/nph.13786

M3 - Journal article

C2 - 26667994

SN - 0028-646X

VL - 209

SP - 1428

EP - 1441

JO - New Phytologist

JF - New Phytologist

IS - 4

ER -