Abstract
Abscission, or organ separation, is accompanied by a marked increase in hydrolases, which are responsible for the degradation of the middle lamella and the loosening of the primary cell wall surrounding cells in the separation layer. We recently reported on the cloning of a tomato (Lycopersicon esculentum) polygalacturonase (PG) cDNA, TAPG1, expressed during leaf and flower abscission. In addition to TAPG1, we have cloned two more PG cDNAs (TAPG2 and TAPG4) that are also expressed during leaf and flower abscission. The peptide sequences for the three abscission PGs are relatively similar (76-93% identity) yet different from the those of tomato fruit PG (38-41% identity). None of the three abscission PG mRNAs are expressed in fruit, stems, petioles, or anthers of fully open flowers. An RNase protection assay revealed that all three PGs are expressed in leaf and flower abscission zones and in pistils of fully open flowers. TAPG4 mRNA is detected much earlier than TAPG1 and TAPG2 mRNA during both leaf and flower abscission.
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- Allen R. L., Lonsdale D. M. Molecular characterization of one of the maize polygalacturonase gene family members which are expressed during late pollen development. Plant J. 1993 Feb;3(2):261–271. doi: 10.1111/j.1365-313x.1993.tb00177.x. [DOI] [PubMed] [Google Scholar]
- Bonghi C., Rascio N., Ramina A., Casadoro G. Cellulase and polygalacturonase involvement in the abscission of leaf and fruit explants of peach. Plant Mol Biol. 1992 Dec;20(5):839–848. doi: 10.1007/BF00027155. [DOI] [PubMed] [Google Scholar]
- Brown S. M., Crouch M. L. Characterization of a gene family abundantly expressed in Oenothera organensis pollen that shows sequence similarity to polygalacturonase. Plant Cell. 1990 Mar;2(3):263–274. doi: 10.1105/tpc.2.3.263. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lashbrook C. C., Gonzalez-Bosch C., Bennett A. B. Two divergent endo-beta-1,4-glucanase genes exhibit overlapping expression in ripening fruit and abscising flowers. Plant Cell. 1994 Oct;6(10):1485–1493. doi: 10.1105/tpc.6.10.1485. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Niogret M. F., Dubald M., Mandaron P., Mache R. Characterization of pollen polygalacturonase encoded by several cDNA clones in maize. Plant Mol Biol. 1991 Dec;17(6):1155–1164. doi: 10.1007/BF00028732. [DOI] [PubMed] [Google Scholar]
- Tebbutt S. J., Rogers H. J., Lonsdale D. M. Characterization of a tobacco gene encoding a pollen-specific polygalacturonase. Plant Mol Biol. 1994 May;25(2):283–297. doi: 10.1007/BF00023244. [DOI] [PubMed] [Google Scholar]
- Thompson D. S., Osborne D. J. A Role for the Stele in Intertissue Signaling in the Initiation of Abscission in Bean Leaves (Phaseolus vulgaris L.). Plant Physiol. 1994 May;105(1):341–347. doi: 10.1104/pp.105.1.341. [DOI] [PMC free article] [PubMed] [Google Scholar]
- del Campillo E., Bennett A. B. Pedicel breakstrength and cellulase gene expression during tomato flower abscission. Plant Physiol. 1996 Jul;111(3):813–820. doi: 10.1104/pp.111.3.813. [DOI] [PMC free article] [PubMed] [Google Scholar]
- von Heijne G. Patterns of amino acids near signal-sequence cleavage sites. Eur J Biochem. 1983 Jun 1;133(1):17–21. doi: 10.1111/j.1432-1033.1983.tb07424.x. [DOI] [PubMed] [Google Scholar]