The gene nomenclature followed in this paper is based on recommendations from the Plant Genome II meeting (Quebedeaux et al., 1995), and it is hoped that, for clarity, the notation is adopted in further publications involving oleosin genes and proteins. The plant species is designated first, followed by the letters Oln, which refer to the oleosin gene, as defined by having a highly conserved 17 residue sequence P-V/L-F-IN-X-F-S-P-V/I-LL/V-P-A-T/G-X-A/T-T contained within a region of around 70 hydrophobic/ non-charged residues. The letters A and B refer to seed- and anther-expressed messages, respectively, and the final digit identifies the specific sequence, in this case designated chronologically with reference to database publication (see Table 1).
Characterization of anther-expressed genes encoding a major class of extracellular oleosin-like proteins in the pollen coat of Brassicaceae†
Article first published online: 12 FEB 2003
The Plant Journal
Volume 9, Issue 5, pages 625–637, May 1996
How to Cite
Ross, J. H.E. and Murphy, D. J. (1996), Characterization of anther-expressed genes encoding a major class of extracellular oleosin-like proteins in the pollen coat of Brassicaceae. The Plant Journal, 9: 625–637. doi: 10.1046/j.1365-313X.1996.9050625.x
- Issue published online: 12 FEB 2003
- Article first published online: 12 FEB 2003
- Received 4 October 1995; revised 24 January 1996; accepted 16 February 1996.
- Cited By
A large, heterogeneous, highly expressed gene family encoding oleosin-like proteins is described in the Brassicaceae. íeven related cDNA sequences were isolated from Brassica napus anther mRNA using RACE-PCR and compared with other recently described anther-specific oleosin-like genes from B. napus. The expression patterns of four representative members of this diverse gene family were analyzed by Northern blotting and in situ hybridization. In all cases, the genes were expressed specifically in the tapetum of 3–5 mm B. napus buds, which contained microspores at the late-vacuolate and bicellular stages of development. The predicted protein products are ordered into subclasses, each of which has a characteristic C-terminal domain, containing different amino acid motifs or repeated residues. Tryphine (pollen coat) fractions from mature B. napus pollen were found to be particularly enriched in polypeptides of apparent molecular weights 32–38 kDa, plus numerous less abundant polypeptides of less than 15 kDa. The N-terminal 15–20 residues of three of these polypeptides (12, 32 and 38 kDa) were found by microsequencing to be identical to parts of the predicted amino acid sequences of three of the tapetal-expressed oleosin-like genes. This indicates the possibility of post-translational modification of these proteins resulting in a cleavage of the primary translation products in order to generate the mature tryphine polypeptides. These data imply that a large and diverse group of oleosin-like proteins is synthesized in the tapeturn of B. napus anthers and that following tapetal degradation, these proteins, possibly in modified form, then relocate to the developing microspores where they eventually constitute some of the major components of the extracellular tryphine of mature pollen grains. These proteins share a conserved 70 amino acid residue hydrophobic domain and are related structurally to the seed-specific intracellular oleosins, although their biological function may be different.