Abstract
BackgroundIn flowering plants, lipid biosynthesis and transport within anthers is essential for male reproductive success. TaMs1, a dominant wheat fertility gene located on chromosome 4BS, has been previously fine mapped and identified to encode a glycosylphosphatidylinositol (GPI)-anchored non-specific lipid transfer protein (nsLTP). Although this gene is critical for pollen exine development, details of its function remains poorly understood.ResultsIn this study, we report that TaMs1 is only expressed from the B sub-genome, with highest transcript abundance detected in anthers containing microspores undergoing pre-meiosis through to meiosis. β-glucuronidase transcriptional fusions further revealed that TaMs1 is expressed throughout all anther cell-types. TaMs1 was identified to be expressed at an earlier stage of anther development relative to genes reported to be necessary for sporopollenin precursor biosynthesis. In anthers missing a functional TaMs1 (ms1c deletion mutant), these same genes were not observed to be mis-regulated, indicating an independent function for TaMs1 in pollen development. Exogenous hormone treatments on GUS reporter lines suggest that TaMs1 expression is increased by both indole-3-acetic acid (IAA) and abscisic acid (ABA). Translational fusion constructs showed that TaMs1 is targeted to the plasma membrane.ConclusionsIn summary, TaMs1 is a wheat fertility gene, expressed early in anther development and encodes a GPI-LTP targeted to the plasma membrane. The work presented provides a new insight into the process of wheat pollen development.
Highlights
In flowering plants, lipid biosynthesis and transport within anthers is essential for male reproductive success
TaMs1 is an anther-specific gene expressed early during anther development TaMs1 transcripts were not detected in pistils, shoots, roots, glume, lemma or palea, transcripts were enriched in anther tissues with their abundance peaking when microspores were at pre-meiosis to meiosis, stage 2 to 4 (Fig. 1a)
To better understand TaMs1’s function, we investigated the timing of its expression relative to wheat orthologues of rice sporopollenin-biosynthetic genes such as TaABCG15, TaCYP703A3, TaCYP704B2, TaDPW and TaPSK1 [4, 6, 48] (Fig. 4)
Summary
Lipid biosynthesis and transport within anthers is essential for male reproductive success. TaMs1, a dominant wheat fertility gene located on chromosome 4BS, has been previously fine mapped and identified to encode a glycosylphosphatidylinositol (GPI)-anchored non-specific lipid transfer protein (nsLTP). This gene is critical for pollen exine development, details of its function remains poorly understood. The underlying genetics of pollen wall development has been intensively investigated through the use of exine-defective mutants in model plants such as A. thaliana and rice among other species [1] These genetic analyses indicate that sporopollenin biosynthesis consists of three conserved metabolic
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