RRC ID 28099
Author del Campillo E, Gaddam S, Mettle-Amuah D, Heneks J.
Title A tale of two tissues: AtGH9C1 is an endo-β-1,4-glucanase involved in root hair and endosperm development in Arabidopsis.
Journal PLoS ONE
Abstract Arabidopsis AtGH9C1 is an endo-β-1,4-glucanase possessing a carbohydrate-binding domain (CBM49). Analysis of AtGH9C1 expression by promoter-reporter GUS, RT-PCR, public transcriptome databases and GFP protein tagging demonstrated a high and selective expression of AtGH9C1 in root hairs and in the endosperm. Expression in root hair cells started prior to bulge formation and continued during hair elongation. AtGH9C1 expression increased with treatments that increase density (ACC) or length (sucrose) of root hairs. Expression in the endosperm extended sequentially to the micropylar, peripheral and chalazal compartments. A mutant with reduced AtGH9C1 expression had a delay in germination and a marked reduction in root hair presence. Complementation of the mutant partially improved both germination and root hair density. Experiments with ectopically expressed AtGH9C1-GFP with and without the CBM49, demonstrated that both forms of the protein are secreted and that CBM49 targets the protein to specific regions of the cell wall, but what makes these regions special is still unknown. The amino acid alignment of angiosperm GH9 genes with C-terminal extensions illustrate that AtGH9C1 belongs to a different clade than its tomato homolog, S1GH9C1. The latter has a CBM49 that was shown to bind crystalline cellulose. We suggest that AtGH9C1 is associated with the weakening of the cell wall during formation and growth of the root hair as well as with the sequential anterior-posterior breakdown of the endosperm cell wall that provides space for the growing embryo. Thus, is likely that the CBM49 of AtGH9C1 recognizes a form of cellulose or glucan polymer that is prevalent in the wall of these specialized tissues and that is different than the one recognized by S1GH9C1.
Volume 7(11)
Pages e49363
Published 2012
DOI 10.1371/journal.pone.0049363
PII PONE-D-12-11775
PMID 23173056
PMC PMC3500288
MeSH Arabidopsis / anatomy & histology Arabidopsis / enzymology* Arabidopsis / genetics Arabidopsis / growth & development* Cell Wall / enzymology Cellulase / genetics Cellulase / metabolism* Endosperm / anatomy & histology Endosperm / enzymology* Endosperm / genetics Endosperm / growth & development* Gene Expression Regulation, Plant Genetic Markers / genetics Glucans / metabolism Hydrolysis Multigene Family / genetics Mutagenesis, Insertional Phenotype Phylogeny Plant Roots / anatomy & histology Plant Roots / enzymology* Plant Roots / genetics Plant Roots / growth & development* Protein Transport Spatio-Temporal Analysis Transcriptome
IF 2.776
Times Cited 4
Arabidopsis / Cultured plant cells, genes pda12555