Genome-Wide Identification of Genes Expressed in Arabidopsis Pistils Specifically along the Path of Pollen Tube Growth

Abstract

Plant reproductive development is dependent on successful pollen-pistil interactions. In crucifers, the pollen tube must breach the stigma surface and burrow through the extracellular matrix of the stigma epidermal cells and transmitting tract cells before reaching its ovule targets. The high degree of specificity in pollen-pistil interactions and the precision of directional pollen tube growth suggest that signals are continually being exchanged between pollen/pollen tubes and cells of the pistil that line their path. However, with few exceptions, little is known about the genes that control these interactions. The specialized functions of stigma epidermal cells and transmitting tract cells are likely to depend on the activity of genes expressed specifically in these cells. In order to identify these genes, we used the Arabidopsis (Arabidopsis thaliana) ATH1 microarray to compare the whole-genome transcriptional profiles of stigmas and ovaries isolated from wild-type Arabidopsis and from transgenic plants in which cells of the stigma epidermis and transmitting tract were specifically ablated by expression of a cellular toxin. Among the 23,000 genes represented on the array, we identified 115 and 34 genes predicted to be expressed specifically in the stigma epidermis and transmitting tract, respectively. Both gene sets were significantly enriched in predicted secreted proteins, including potential signaling components and proteins that might contribute to reinforcing, modifying, or remodeling the structure of the extracellular matrix during pollination. The possible role of these genes in compatible and incompatible pollen-pistil interactions is discussed.

Whole Genome Analysis of Gene Expression Reveals Coordinated Activation of Signaling and Metabolic Pathways during Pollen-Pistil Interactions in Arabidopsis

“…A primary transcriptomic comparison of UP, ovules, and siliques enriched the UP and ovule data sets for stage-specific transcripts by excluding common sporophyte-expressed genes potentially involved in carpel and ovule determination, such as SEEDSTICK (STK; Rounsley et al, 1995) and SHATTERPROOF1 (SHP1; Flanagan et al, 1996), a phosphogluconolactonase (At5g24420) that is expressed in ovule integuments and in the ovary wall (Scutt et al, 2003), as well as genes involved in later stages of seed development, such as MEDEA (MEA; Vielle-Calzada et al, 1999), FERTILIZATION INDE-PENDENT SEED2 (Luo et al, 1999), and FLOWERING WAGENINGEN (Kinoshita et al, 2004). Using the parameters outlined in "Materials and Methods" and further comparison with publicly available data sets (Zimmermann et al, 2004;Tung et al, 2005;Yu et al, 2005;Steffen et al, 2007;Borges et al, 2008;Wang et al, 2008;Qin et al, 2009;Wuest et al, 2010), a total of 42 genes were considered enriched or preferentially expressed in ovules (Supplemental File S1). As anticipated, 27 out of 42 transcripts preferentially expressed in ovules and 96 out of 1,275 ovule-enriched transcripts were previously reported to be expressed specifically in the embryo sac or enriched in female gametophytic cells (Supplemental File S1; Yu et al, 2005;Johnston et al, 2007;Punwani et al, 2007;Steffen et al, 2007;Wuest et al, 2010).…”

“…The transcriptional profiles of pollen (Becker et al, 2003;Twell, 2003, 2004;Pina et al, 2005; for review, see Becker and Feijó , 2007), embryo sac (Yu et al, 2005;Johnston et al, 2007;Jones-Rhoades et al, 2007;Steffen et al, 2007), pistil (Scutt et al, 2003;Tung et al, 2005), and embryo or seed developmental stages (Chen et al, 2001;Hennig et al, 2004;Yoshida et al, 2005, Le et al, 2010 were recently analyzed. More notably, recent progress in the isolation of Arabidopsis (Arabidopsis thaliana) gametes allowed genomewide expression profiling of purified sperm cells (Borges et al, 2008) as well as of isolated egg and central cells (Wuest et al, 2010).…”

Global Expression Profiling Applied to the Analysis of Arabidopsis Stamen Development

“…However, in plants, most of the microarray-based analyses that have been conducted so far have been done using whole organs (e.g. leaves, roots, or flowers; Zik and Irish, 2003;Wellmer et al, 2004;Ma et al, 2005;Tung et al, 2005), and only a few have focused on determining gene expression in specific cell types (Honys and Twell, 2004;Birnbaum et al, 2005). Consequently, detailed information on cell-type-specific gene expression is currently limited.…”

Isolation of a gene encoding for a class III peroxidase in female flower of Corylus avellana L.

“…One of the possible role of peroxidases in the pollen-stigma interaction could be the promotion of pollen tube penetration and growth within the stigma, by loosening stigma cell wall components [41]. Microarray analysis carried out by Tung et al [14] in stigmas and transmitting tracts of A. thaliana revealed the presence of a consistent group of genes predicted to encode proteins with N-terminal signal peptides, as found in CavPrx. Among these, three peroxidases (AtPrx28, AtPrx39 and AtPrx58) were identified as putative cell wall-localized enzymes that could have a role for the stigmatic extracellular matrix modification during pollination and pollen tube penetration.…”

“…Despite most of plant peroxidases are active in all part of the plant [5,7] some example of localized peroxidases in particular tissue/organ exist in literature, as reported in the introduction. In particular, five peroxidases were identified to be expressed in particular parts of the flower: GhPrx37 in G. hirsutum resulted expressed only in stamen and pollen [12]; SsqPrx01 in S. squalidus was demonstrated to be localized in the stigmatic papillae and expressed only in stigmas with maximal level at anthesis [6]; AtPrx28, AtPrx39 and AtPrx58 in A. thaliana resulted expressed in stigmas [13,14]. Phylogenetic analysis was carried out in order to understand the relation among CavPrx and other peroxidases with the greatest sequence similarity.…”