e-journal

The cell wall pectic polymer rhamnogalacturonan-II is required for proper pollen tube elongation: implications of a putative sialyltransferase-like protein

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† Background and Aims:
Rhamnogalacturonan-II (RG-II) is one of the pectin motifs found in the cellwall of all land plants. It contains sugars such as 2-keto-3-deoxy-D-lyxo-heptulosaric acid (Dha) and 2-keto-3-deoxy-D-manno-octulosonic
acid (Kdo), and within thewall RG-II is mostly found as a dimer via a borate diester cross-link.To date, little is knownregarding the biosynthesis of this motif. Here, after a brief reviewof our current knowledge on RG-II structure, biosynthesis and function in plants, this study explores the implications of the presence of a Golgi-localized sialyltransferase-like 2 (SIA2) protein that is possibly involved in the transfer of Dha or Kdo in the RG-II of Arabidopsis thaliana pollen tubes, a fast-growing cell type used as a model for the study of cell elongation.

† Methods:
Two heterozygous mutant lines of arabidopsis (sia2-1+/– and qrt1 × sia2-2+/–) were investigated. sia2-2+/– was in a quartet1 background and the inserted T-DNA contained the reporter gene β-glucuronidase (GUS) under the pollen-specific promoter LAT52. Pollen germination and pollen tube phenotype and growth were analysed both in vitro and in vivo by microscopy.

† Key Results:
Self-pollination of heterozygous lines produced no homozygous plants in the progeny, which may suggest that the mutation could be lethal. Heterozygous mutants displayed a much lower germination rate overall and exhibited a substantial delay in germination (20 h of delay to reach 30%of pollen grain germination compared
with the wild type). In both lines, mutant pollen grains that were able to produce a tube had tubes that were either bursting, abnormal (swollen or dichotomous branching tip) or much shorter compared with wild-type pollen tubes. In vivo, mutant pollen tubes were restricted to the style, whereas the wild-type pollen tubes were detected at the base of the ovary.

†Conclusions:
This study highlights that the mutation in arabidopsis SIA2 encoding a sialyltransferase-like protein that may transfer Dha or Kdo on the RG-II motif has a dramatic effect on the stability of the pollen tube cell wall.

Key words: Rhamnogalacturonan-II, RG-II, Dha, Kdo, pollen tube, plant cell wall, sialyltransferase-like protein, pectin motif, Arabidopsis thaliana.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2014

Deskripsi Fisik

Annals of Botany 114: 1177–1188, 2014

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

114: 2014

Subjek

EKOFISIOLOGI TANAMAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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