Polygalacturonase in tomatoes

Pressey, R. (1988). Reevaluation of the changes in polygalacturonases in tomatoes during ripening. Planta 174, 39-43. 

Pressey, R. Avants, J.K. (1973) Two forms of polygalacturonase in tomatoes. Biochimica et Biophysica Acta. 309. 363-369. 

Hobson, G.E. (1964) Polygalacturonase in normal and almormal tomato finit. Biochemical Journal. 92.324-332. 

Galacturonanases in the parenchyma have been shown to be wall-bound in peach (both endo- and exo-enzymes),625 apple (exo-enzyme only),621 tomato (endo-enzyme),499 and pear (unspecified activity).641 Increases in the level of polygalacturonase activity during ripening have been demonstrated in tomato,499,642-644 avocado,615,633 peach645 date,636 cucumber,631,646 and pear,641 and, in tomato,644 avocado,615 and cucumber,631 this increase is associated with the respiratory climacteric following a transient burst of ethylene production. In the mutant rin tomato fruit, which does not ripen, this increase in galacturonanase does not occur.644... 

Grierson, D., Slater, D., Spiers, J. Tucker, G.A. (1985). The appearance of polygalacturonase mRNA in tomatoes one of a series of changes in gene expression during development and ripening. Planta 163, 263-71. 

Sheehy, R.E., Kramer, M. Hiatt, W.R. (1988). Reduction of polygalacturonase activity in tomato fruit by antisense RNA. Proceedings of the National Academy of Sciences (USA) 85, 8805-9. 

Lycopene synthesis in the rin mutant was enhanced by high 02 in the presence of 10 ppm ethylene (Frenkel and Garrison, 1976). On the other hand, ethanol inhibits ripening and the synthesis of tomato lycopene (Saltveit and Mencarelli, 1988). In addition, Sheehy et al. (1988) found that a reduction in polygalacturonase did not affect biosynthesis of lycopene. Lampe and Watada (1971) and Mohr (1979) pointed out that the lycopene content in tomato fruits may be increased by improving the practices at times of selection of varieties, fertilization and harvest. 

Enzymes other than peroxidase and catalase have been used less frequently to monitor adequacy of heat treatment. Some enzymes that have been used include polyphenol oxidase for off-color development in fruits, polygalacturonase for loss of consistency in tomatoes, potatoes and eggplants and lipoxygenase and lipase for... 

Polygalacturonases in Other Plant Tissues. PG activity is usually associated with ripe fruit tissues and, as we have seen, the activity can he due to an endo-PG, exo-PG, or to hoth enzymes. However, I have already mentioned the occurrence of PG activity in unripe tomatoes (21). pears (45). and cucumbers (52). The enzymes in green tomatoes and cucumbers have been characterized as exo-PG s. 

Fraser et al. [92] also overexpressed the phytoene synthase (CRTR-B) gene, in this case from Erwinia uredovora, in tomato under the control of the tomato polygalacturonase promoter, resulting in 2.4-, 1.8-, and 2.2-fold higher contents of lycopene, p-carotene, and lutein, respectively, than the controls. In this case. 

Pectinesterases.—The pectinesterase activities in tomatoes stored at different temperatures have been determined. The level of activity is low in mature green fruit but increased rapidly at ca. 20 °C - but not at either 4 or 33 C. The storage-life of tomatoes kept at 33 °C for several days is increased, owing to suppression of the polygalacturonase activity. Multiple forms of the enzyme are responsible for the pectinesterase activity of tomatoes one of the forms has been characterized. ... 

The hSubunit of Tomato Fruit Polygalacturonase Isoenzyme 1 Defines a New Class of Plant Cell Proteins Involved in Pectin Metabolism AroGPs (Aromatic Amino Acid Rich Glyco Proteins)... 

Expression of polygalacturonase and pectinesterase in normal and transgenic tomatoes. 

Knegt,E., Vermeer,E, Pak,C and Bruinsma,J (1991) Function of the polygalacturonase converter in ripening tomato finit. Physiologia Plantarum. 82.237-242. 

Moore,T and Bennett,A.B (1994) Tomato finit polygalacturonase isozyme-1. Characterisation of the beta-subunit and its state of assembly in vivo. Plant Physiology. 106. 1461-1469. 

Pogson,B.J.,Brady,C.J and Oir,G.R (1991) On the occurance and structure of subunits of endo-polygalacturonase isoforms in mature-green and ripening tomato finit. Australian Journal of Plant Physiology. 18. 65-79. 

Tucker,G.A.,Robertson,N.G. and Grierson,D. (1980) Changes in polygalacturonase isoenzymes during the ripening of normal and mutant tomato fiuit. European Journal of Biochemistry. 112,119-124. 

Tucker, G.A., Robertson, N.G. Grierson, D. (1981) The conversion of tomato Suit polygalacturonase isoenzyme 2 into isoenzyme I in vitro. European Journal of Biochemistry. 115. 87-90. 

Bird CR, Smith CJS, Ray JA, Moureau P, Bevan MJ, Birds AS, Hughes S, Morris PC, Grierson D, Schuch W (1988) The tomato polygalacturonase gene and ripening specific expression in trangenic plants. Plant Mol Biol 11 651-662... 

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