Chemical Visualization of an Attractant Peptide, LURE

Abstract

The pollen tube attractant peptide LUREs of Torenia fournieri are diffusible peptides that attract pollen tubes in vitro. Here, we report a method enabling the direct visualization of a LURE peptide without inhibiting its attraction activity by conjugating it with the Alexa Fluor 488 fluorescent dye. After purifying and refolding the recombinant LURE2 with a polyhistidine tag, its amino groups were targeted for conjugation with the Alexa Fluor dye. Labeling of LURE2 was confirmed by its fluorescence and mass spectrometry. In our in vitro assay using gelatin beads, Alexa Fluor 488-labeled LURE2 appeared to have the same activity as unlabeled LURE2. Using the labeled LURE2, the relationship between the spatiotemporal change of distribution and activity of LURE2 was examined. LURE2 attracted pollen tubes when embedded in gelatin beads, but hardly at all when in agarose beads. Direct visualization suggested that the significant difference between these conditions was the retention of LURE2 in the gelatin bead, which might delay diffusion of LURE2 from the bead. Direct visualization of LURE peptide may open the way to studying the spatiotemporal dynamics of LURE in pollen tube attraction.

Discovery of novel transcripts and gametophytic functions via RNA-seq analysis of maize gametophytic transcriptomes

“…Thus, in total, three different sets of DEFL genes were found, each overrepresented among the transcripts showing that expression character: ES-enriched; MPenriched; and dual gametophyte-enriched. Some members of this family have previously been shown to be expressed in synergids in maize and to function as pollen tube attractants in Torenia [28,[44][45][46][47].…”

Cell Type-Specific Transcriptome of Brassicaceae Stigmatic Papilla Cells From a Combination of Laser Microdissection and RNA Sequencing

“…Papilla cells have various roles in this step, such as discrimination of pollen grains for inter- and intraspecies barriers, pollen hydration, supply of stigmatic resources for pollen germination and pollen tube elongation, and pollen tube guidance (de Nettancourt 2001, Goto et al 2011). However, the molecular basis of these mechanisms of pollination is still largely unclear (Hiroi et al 2013).…”

Gametophytic Pollen Tube Guidance: Attractant Peptides, Gametic Controls, and Receptors

“…The rapid response of pollen tubes to attractant peptides is advantageous for real-time analysis (Takeuchi and Higashiyama, 2016). It should be noted that a very small number of LURE peptides, approximately 1,000 molecules in a bead, can attract pollen tubes in Torenia, which is also a considerable advantage for single-molecule analysis (Okuda et al, 2009;Goto et al, 2011). Microfluidics allow precise control of pollen tube guidance in real time using the microscope (Horade et al, 2013;Sanati Nezhad et al, 2014;Sato et al, 2015).…”