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

We report 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. 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-silencedmore » 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. 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.« less
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [2] ;  [3] ;  [5] ;  [6]
  1. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of Copenhagen (Denmark)
  2. Univ. of California, Berkeley, CA (United States)
  3. Univ. of Georgia, Athens, GA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Melbourne (Australia)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-05CH11231; 11-116795; DBI-042168; IOS-0923992
Accepted Manuscript
Journal Name:
BMC Plant Biology
Additional Journal Information:
Journal Volume: 16; Journal Issue: 1; Journal ID: ISSN 1471-2229
BioMed Central
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES Arabidopsis thaliana; Nicotiana benthamiana; Cell wall; Rhamnogalacturonan-I; Pectin; Pollen tube