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Three different polygalacturonases are expressed in tomato leaf and flower abscission, each with a different temporal
P Kalaitzis1, T Solomos, M L Tucker
1Plant Molecular Biology Laboratory, United States Department of Agriculture, Beltsville, Maryland 20705, USA.
Plant Physiology
|April 1, 1997
Summary
Researchers identified three new polygalacturonase (PG) genes in tomato plants that are active during organ abscission. These genes, TAPG1, TAPG2, and TAPG4, play a role in leaf and flower separation.
Area of Science:
- Plant Biology
- Molecular Biology
- Biochemistry
Background:
- Abscission, the process of organ separation in plants, involves increased hydrolase activity for cell wall degradation.
- Polygalacturonases (PGs) are key enzymes in cell wall modification during abscission.
Purpose of the Study:
- To identify and characterize novel polygalacturonase (PG) cDNAs involved in tomato (Lycopersicon esculentum) leaf and flower abscission.
- To investigate the expression patterns of these newly identified PG genes in different plant tissues and during abscission.
Main Methods:
- Cloning of polygalacturonase (PG) cDNAs from tomato.
- RNAse protection assays to determine gene expression levels in various tissues and during abscission.
Main Results:
- Three new PG cDNAs, TAPG1, TAPG2, and TAPG4, were cloned and found to be expressed during leaf and flower abscission.
- The deduced peptide sequences of these abscission-related PGs show high similarity to each other (76-93% identity) but are distinct from fruit PGs (38-41% identity).
- TAPG4 mRNA expression precedes that of TAPG1 and TAPG2 during both leaf and flower abscission.
Conclusions:
- Tomato leaf and flower abscission involve at least three distinct PG genes.
- These abscission-specific PGs are differentially expressed, with TAPG4 being the earliest detected.
- The identified PGs are likely crucial for the degradation of the middle lamella during the abscission process.