Dataset Information

Expression-based and co-localization detection of arabinogalactan protein 6 and arabinogalactan protein 11 interactors in Arabidopsis pollen and pollen tubes.

ABSTRACT: BACKGROUND: Arabinogalactan proteins (AGPs) are cell wall proteoglycans that have been shown to be important for pollen development. An Arabidopsis double null mutant for two pollen-specific AGPs (agp6 agp11) showed reduced pollen tube growth and compromised response to germination cues in vivo. A microarray experiment was performed on agp6 agp11 pollen tubes to search for genetic interactions in the context of pollen tube growth. A yeast two-hybrid experiment for AGP6 and AGP11 was also designed. RESULTS: The lack of two specific AGPs induced a meaningful shift in the gene expression profile. In fact, a high number of genes showed altered expression levels, strengthening the case that AGP6 and AGP11 are involved in complex phenomena. The expression levels of calcium- and signaling-related genes were found to be altered, supporting the known roles of the respective proteins in pollen tube growth. Although the precise nature of the proposed interactions needs further investigation, the putative involvement of AGPs in signaling cascades through calmodulin and protein degradation via ubiquitin was indicated. The expression of stress-, as well as signaling- related, genes was also changed; a correlation that may result from the recognized similarities between signaling pathways in both defense and pollen tube growth.The results of yeast two-hybrid experiments lent further support to these signaling pathways and revealed putative AGP6 and AGP11 interactors implicated in recycling of cell membrane components via endocytosis, through clathrin-mediated endosomes and multivesicular bodies. CONCLUSIONS: The data presented suggest the involvement of AGP6 and AGP11 in multiple signaling pathways, in particular those involved in developmental processes such as endocytosis-mediated plasma membrane remodeling during Arabidopsis pollen development. This highlights the importance of endosomal trafficking pathways which are rapidly emerging as fundamental regulators of the wall physiology.

SUBMITTER: Costa M

PROVIDER: S-EPMC3546934 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Expression-based and co-localization detection of arabinogalactan protein 6 and arabinogalactan protein 11 interactors in Arabidopsis pollen and pollen tubes.

Costa Mário M Nobre Margarida Sofia MS Becker Jörg D JD Masiero Simona S Amorim Maria Isabel MI Pereira Luís Gustavo LG Coimbra Sílvia S

BMC plant biology 20130108

<h4>Background</h4>Arabinogalactan proteins (AGPs) are cell wall proteoglycans that have been shown to be important for pollen development. An Arabidopsis double null mutant for two pollen-specific AGPs (agp6 agp11) showed reduced pollen tube growth and compromised response to germination cues in vivo. A microarray experiment was performed on agp6 agp11 pollen tubes to search for genetic interactions in the context of pollen tube growth. A yeast two-hybrid experiment for AGP6 and AGP11 was also ...[more]

PMID: 23297674

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Project description:Background and aimsCell wall pectins and arabinogalactan proteins (AGPs) are important for pollen tube growth. The aim of this work was to study the temporal and spatial dynamics of these compounds in olive pollen during germination.MethodsImmunoblot profiling analyses combined with confocal and transmission electron microscopy immunocytochemical detection techniques were carried out using four anti-pectin (JIM7, JIM5, LM5 and LM6) and two anti-AGP (JIM13 and JIM14) monoclonal antibodies.Key resultsPectin and AGP levels increased during olive pollen in vitro germination. (1 ? 4)-?-d-Galactans localized in the cytoplasm of the vegetative cell, the pollen wall and the apertural intine. After the pollen tube emerged, galactans localized in the pollen tube wall, particularly at the tip, and formed a collar-like structure around the germinative aperture. (1 ? 5)-?-l-Arabinans were mainly present in the pollen tube cell wall, forming characteristic ring-shaped deposits at regular intervals in the sub-apical zone. As expected, the pollen tube wall was rich in highly esterified pectic compounds at the apex, while the cell wall mainly contained de-esterified pectins in the shank. The wall of the generative cell was specifically labelled with arabinans, highly methyl-esterified homogalacturonans and JIM13 epitopes. In addition, the extracellular material that coated the outer exine layer was rich in arabinans, de-esterified pectins and JIM13 epitopes.ConclusionsPectins and AGPs are newly synthesized in the pollen tube during pollen germination. The synthesis and secretion of these compounds are temporally and spatially regulated. Galactans might provide mechanical stability to the pollen tube, reinforcing those regions that are particularly sensitive to tension stress (the pollen tube-pollen grain joint site) and mechanical damage (the tip). Arabinans and AGPs might be important in recognition and adhesion phenomena of the pollen tube and the stylar transmitting cells, as well as the egg and sperm cells.

Project description:BackgroundThe pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana.MethodsHere, we present reliable approaches for ultrastructural studies of Arabidopsis PTs, as well as an efficient technique for immunogold detection of cell wall epitopes. Using different fixation and embedding strategies, we show the amount of PT ultrastructural details that can be obtained by the different methods.ResultsDozens of cross-sections can be obtained simultaneously by the approach, which facilitates and shortens the time for evaluation. In addition to in vitro-grown PTs, our study follows the route of PTs from germination, growth along the pistil, to the penetration of the dense stylar tissue, which requires considerable mechanical forces. To this end, PTs have different strategies from growing between cells but also between the protoplast and the cell wall and even within each other, where they share a partly common cell wall. The separation of PT cell walls in an outer and an inner layer reported for many plant species is less clear in Arabidopsis PTs, where these cell wall substructures are connected by a distinct transition zone.ConclusionsThe major advancement of this method is the effective production of a large number of longitudinal and cross-sections that permits obtaining a detailed and representative picture of pollen tube structures in an unprecedented way. This is particularly important when comparing PTs of wild type and mutants to identify even subtle alterations in cytoarchitecture. Arabidopsis is an excellent plant for genetic manipulation, yet the PTs, several-times smaller compared to tobacco or lily, represent a technical challenge. This study reveals a method to overcome this problem and make Arabidopsis PTs more amenable to a combination of genetic and ultrastructural analyses.

Dataset Information

Expression-based and co-localization detection of arabinogalactan protein 6 and arabinogalactan protein 11 interactors in Arabidopsis pollen and pollen tubes.

Publications

Expression-based and co-localization detection of arabinogalactan protein 6 and arabinogalactan protein 11 interactors in Arabidopsis pollen and pollen tubes.

Similar Datasets

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