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A DUF-246 family glycosyltransferase-like gene affects male fertility and the biosynthesis of pectic arabinogalactans.

Stonebloom S, Ebert B, Xiong G, Pattathil S, Birdseye D, Lao J, Pauly M, Hahn MG, Heazlewood JL, Scheller HV - BMC Plant Biol. (2016)

Bottom Line: NbPAGR-silenced plants exhibited reduced internode and petiole expansion.Immunological and linkage analyses support that RG-I has reduced type-I arabinogalactan content and reduced branching of the RG-I backbone in NbPAGR-silenced plants.Together, results support a function for PAGR in the biosynthesis of RG-I arabinogalactans and illustrate the essential roles of these polysaccharides in vegetative and reproductive plant growth.

View Article: PubMed Central - PubMed

Affiliation: Joint BioEnergy Institute and Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.

ABSTRACT

Background: Pectins are a group of structurally complex plant cell wall polysaccharides whose biosynthesis and function remain poorly understood. The pectic polysaccharide rhamnogalacturonan-I (RG-I) has two types of arabinogalactan side chains, type-I and type-II arabinogalactans. To date few enzymes involved in the biosynthesis of pectin have been described. Here we report the identification of a highly conserved putative glycosyltransferase encoding gene, Pectic ArabinoGalactan synthesis-Related (PAGR), affecting the biosynthesis of RG-I arabinogalactans and critical for pollen tube growth.

Results: T-DNA insertions in PAGR were identified in Arabidopsis thaliana and were found to segregate at a 1:1 ratio of heterozygotes to wild type. We were unable to isolate homozygous pagr mutants as pagr mutant alleles were not transmitted via pollen. In vitro pollen germination assays revealed reduced rates of pollen tube formation in pollen from pagr heterozygotes. To characterize a loss-of-function phenotype for PAGR, the Nicotiana benthamiana orthologs, NbPAGR-A and B, were transiently silenced using Virus Induced Gene Silencing. NbPAGR-silenced plants exhibited reduced internode and petiole expansion. Cell wall materials from NbPAGR-silenced plants had reduced galactose content compared to the control. Immunological and linkage analyses support that RG-I has reduced type-I arabinogalactan content and reduced branching of the RG-I backbone in NbPAGR-silenced plants. Arabidopsis lines overexpressing PAGR exhibit pleiotropic developmental phenotypes and the loss of apical dominance as well as an increase in RG-I type-II arabinogalactan content.

Conclusions: Together, results support a function for PAGR in the biosynthesis of RG-I arabinogalactans and illustrate the essential roles of these polysaccharides in vegetative and reproductive plant growth.

No MeSH data available.


Related in: MedlinePlus

Pollen phenotypes of pagr heterozygotes. Pollen from segregating PAGR/PAGR (a), pagr-1/PAGR (b), PAGR/PAGR (c) and pagr-2/PAGR (d) plants stained equally with Alexander’s stain indicating that pagr pollen is viable. Scale bars 50 μm. In vitro pollen germination assays show reduced germination rates compared to the wild type (e) for pollen from pagr-1/PAGR (f) and pagr-2/PAGR (g) plants. Scale bars 100 μm
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Fig2: Pollen phenotypes of pagr heterozygotes. Pollen from segregating PAGR/PAGR (a), pagr-1/PAGR (b), PAGR/PAGR (c) and pagr-2/PAGR (d) plants stained equally with Alexander’s stain indicating that pagr pollen is viable. Scale bars 50 μm. In vitro pollen germination assays show reduced germination rates compared to the wild type (e) for pollen from pagr-1/PAGR (f) and pagr-2/PAGR (g) plants. Scale bars 100 μm

Mentions: We therefore tested for phenotypes affecting pollen in pagr heterozygotes. The viability of pollen grains was tested with Alexander’s stain in segregating wild-type and pagr heterozygous plants [26]. More than 95 % of pollen grains from pagr-1/PAGR, pagr-2/PAGR and PAGR/PAGR plants stained purple with Alexander’s stain (Fig. 2a-d) indicating that development proceeds normally in pagr pollen prior to anthesis.Fig. 2


A DUF-246 family glycosyltransferase-like gene affects male fertility and the biosynthesis of pectic arabinogalactans.

Stonebloom S, Ebert B, Xiong G, Pattathil S, Birdseye D, Lao J, Pauly M, Hahn MG, Heazlewood JL, Scheller HV - BMC Plant Biol. (2016)

Pollen phenotypes of pagr heterozygotes. Pollen from segregating PAGR/PAGR (a), pagr-1/PAGR (b), PAGR/PAGR (c) and pagr-2/PAGR (d) plants stained equally with Alexander’s stain indicating that pagr pollen is viable. Scale bars 50 μm. In vitro pollen germination assays show reduced germination rates compared to the wild type (e) for pollen from pagr-1/PAGR (f) and pagr-2/PAGR (g) plants. Scale bars 100 μm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4836069&req=5

Fig2: Pollen phenotypes of pagr heterozygotes. Pollen from segregating PAGR/PAGR (a), pagr-1/PAGR (b), PAGR/PAGR (c) and pagr-2/PAGR (d) plants stained equally with Alexander’s stain indicating that pagr pollen is viable. Scale bars 50 μm. In vitro pollen germination assays show reduced germination rates compared to the wild type (e) for pollen from pagr-1/PAGR (f) and pagr-2/PAGR (g) plants. Scale bars 100 μm
Mentions: We therefore tested for phenotypes affecting pollen in pagr heterozygotes. The viability of pollen grains was tested with Alexander’s stain in segregating wild-type and pagr heterozygous plants [26]. More than 95 % of pollen grains from pagr-1/PAGR, pagr-2/PAGR and PAGR/PAGR plants stained purple with Alexander’s stain (Fig. 2a-d) indicating that development proceeds normally in pagr pollen prior to anthesis.Fig. 2

Bottom Line: NbPAGR-silenced plants exhibited reduced internode and petiole expansion.Immunological and linkage analyses support that RG-I has reduced type-I arabinogalactan content and reduced branching of the RG-I backbone in NbPAGR-silenced plants.Together, results support a function for PAGR in the biosynthesis of RG-I arabinogalactans and illustrate the essential roles of these polysaccharides in vegetative and reproductive plant growth.

View Article: PubMed Central - PubMed

Affiliation: Joint BioEnergy Institute and Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.

ABSTRACT

Background: Pectins are a group of structurally complex plant cell wall polysaccharides whose biosynthesis and function remain poorly understood. The pectic polysaccharide rhamnogalacturonan-I (RG-I) has two types of arabinogalactan side chains, type-I and type-II arabinogalactans. To date few enzymes involved in the biosynthesis of pectin have been described. Here we report the identification of a highly conserved putative glycosyltransferase encoding gene, Pectic ArabinoGalactan synthesis-Related (PAGR), affecting the biosynthesis of RG-I arabinogalactans and critical for pollen tube growth.

Results: T-DNA insertions in PAGR were identified in Arabidopsis thaliana and were found to segregate at a 1:1 ratio of heterozygotes to wild type. We were unable to isolate homozygous pagr mutants as pagr mutant alleles were not transmitted via pollen. In vitro pollen germination assays revealed reduced rates of pollen tube formation in pollen from pagr heterozygotes. To characterize a loss-of-function phenotype for PAGR, the Nicotiana benthamiana orthologs, NbPAGR-A and B, were transiently silenced using Virus Induced Gene Silencing. NbPAGR-silenced plants exhibited reduced internode and petiole expansion. Cell wall materials from NbPAGR-silenced plants had reduced galactose content compared to the control. Immunological and linkage analyses support that RG-I has reduced type-I arabinogalactan content and reduced branching of the RG-I backbone in NbPAGR-silenced plants. Arabidopsis lines overexpressing PAGR exhibit pleiotropic developmental phenotypes and the loss of apical dominance as well as an increase in RG-I type-II arabinogalactan content.

Conclusions: Together, results support a function for PAGR in the biosynthesis of RG-I arabinogalactans and illustrate the essential roles of these polysaccharides in vegetative and reproductive plant growth.

No MeSH data available.


Related in: MedlinePlus