Reevaluation of the changes in polygalacturonases in tomatoes during ripening
1Richard B. Russell Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, College Station Road, P.O. Box 5677, 30613, Athens, GA, USA.
Planta
|November 14, 2013
Summary
Researchers developed a method to separate tomato polygalacturonases (PG) I and II. They found that PG II is the only native PG in tomatoes, forming PG I when combined with a converter protein during ripening.
Area of Science:
- Plant Biochemistry
- Enzymology
- Fruit Ripening
Background:
- Polygalacturonases (PG) are key enzymes in fruit ripening.
- Understanding the specific forms and origins of PGs in tomatoes (Lycopersicon esculentum Mill.) is crucial for studying fruit softening.
Purpose of the Study:
- To develop a differential extraction procedure for distinguishing between polygalacturonase I (PG I) and polygalacturonase II (PG II) in tomatoes.
- To investigate the presence and changes of PG I, PG II, and PG converter during tomato ripening.
Main Methods:
- Differential extraction of tomato pericarp using varying pH and salt concentrations (1.0 M NaCl, pH 6.0, pH 1.6, pH 10.0).
- Analysis of enzyme activity and protein levels in different extracts.
- Comparison of enzyme profiles across various ripening stages.
Main Results:
- A procedure was established to extract PG I and PG II differentially.
- Water extraction at pH 1.6 selectively isolated PG II.
- PG I was found to be formed from PG II and a PG converter protein, which increases during ripening.
- PG II is the sole endogenous PG in tomatoes, appearing and increasing as ripening commences.
Conclusions:
- The developed method allows for the differentiation of PG I and PG II.
- Tomato ripening involves the conversion of PG II into PG I through interaction with the PG converter.
- PG II is the primary endogenous polygalacturonase in tomatoes.
