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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

PAGR overexpression phenotypes in Arabidopsis rosettes. a 4-week old wild type, b35S::PAGR-YFP line 6, and c35S::PAGR-YFP line 9 plants. d 6-week old wild type, e35S::PAGR-YFP line 6 and f35S::PAGR-YFP line 9 plants. 35S::PAGR-YFP inflorescences exhibit pleiotropic phenotypes. g Normal wild type inflorescence. h Inflorescence displaying swollen floral pedicels in 35S::PAGR-YFP line 6. i Altered phyllotaxy and swollen pedicels in 35S::PAGR-YFP line 9. j Close-up of swollen pedicel tissues in 35S::PAGR-YFP line 6. k Fasciation in 35S::PAGR-YFP line 6. l Swollen pedicels and altered patterning in 35S::PAGR-YFP line 9
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Fig5: PAGR overexpression phenotypes in Arabidopsis rosettes. a 4-week old wild type, b35S::PAGR-YFP line 6, and c35S::PAGR-YFP line 9 plants. d 6-week old wild type, e35S::PAGR-YFP line 6 and f35S::PAGR-YFP line 9 plants. 35S::PAGR-YFP inflorescences exhibit pleiotropic phenotypes. g Normal wild type inflorescence. h Inflorescence displaying swollen floral pedicels in 35S::PAGR-YFP line 6. i Altered phyllotaxy and swollen pedicels in 35S::PAGR-YFP line 9. j Close-up of swollen pedicel tissues in 35S::PAGR-YFP line 6. k Fasciation in 35S::PAGR-YFP line 6. l Swollen pedicels and altered patterning in 35S::PAGR-YFP line 9

Mentions: To investigate the effects of PAGR overexpression we expressed PAGR-YFP in Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Two independent 35S::PAGR-YFP lines were selected for further analysis. Seedlings overexpressing PAGR had a slightly dwarfed phenotype, with rosettes growing more slowly than the wild type (Fig. 5a-c). When grown under short-day conditions PAGR overexpressing plants lost apical dominance and developed multiple rosettes of tangled leaves (Fig. 5d-f). Under long-day conditions loss of apical dominance was observed infrequently. Inflorescences of 35S::PAGR-YFP plants had variable pleiotropic phenotypes each exhibited in independent transformants including fasciation, increased branching, swollen translucent floral pedicels and deficiencies in internode expansion (Fig. 5h-l).Fig. 5


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)

PAGR overexpression phenotypes in Arabidopsis rosettes. a 4-week old wild type, b35S::PAGR-YFP line 6, and c35S::PAGR-YFP line 9 plants. d 6-week old wild type, e35S::PAGR-YFP line 6 and f35S::PAGR-YFP line 9 plants. 35S::PAGR-YFP inflorescences exhibit pleiotropic phenotypes. g Normal wild type inflorescence. h Inflorescence displaying swollen floral pedicels in 35S::PAGR-YFP line 6. i Altered phyllotaxy and swollen pedicels in 35S::PAGR-YFP line 9. j Close-up of swollen pedicel tissues in 35S::PAGR-YFP line 6. k Fasciation in 35S::PAGR-YFP line 6. l Swollen pedicels and altered patterning in 35S::PAGR-YFP line 9
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig5: PAGR overexpression phenotypes in Arabidopsis rosettes. a 4-week old wild type, b35S::PAGR-YFP line 6, and c35S::PAGR-YFP line 9 plants. d 6-week old wild type, e35S::PAGR-YFP line 6 and f35S::PAGR-YFP line 9 plants. 35S::PAGR-YFP inflorescences exhibit pleiotropic phenotypes. g Normal wild type inflorescence. h Inflorescence displaying swollen floral pedicels in 35S::PAGR-YFP line 6. i Altered phyllotaxy and swollen pedicels in 35S::PAGR-YFP line 9. j Close-up of swollen pedicel tissues in 35S::PAGR-YFP line 6. k Fasciation in 35S::PAGR-YFP line 6. l Swollen pedicels and altered patterning in 35S::PAGR-YFP line 9
Mentions: To investigate the effects of PAGR overexpression we expressed PAGR-YFP in Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Two independent 35S::PAGR-YFP lines were selected for further analysis. Seedlings overexpressing PAGR had a slightly dwarfed phenotype, with rosettes growing more slowly than the wild type (Fig. 5a-c). When grown under short-day conditions PAGR overexpressing plants lost apical dominance and developed multiple rosettes of tangled leaves (Fig. 5d-f). Under long-day conditions loss of apical dominance was observed infrequently. Inflorescences of 35S::PAGR-YFP plants had variable pleiotropic phenotypes each exhibited in independent transformants including fasciation, increased branching, swollen translucent floral pedicels and deficiencies in internode expansion (Fig. 5h-l).Fig. 5

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