Tomato , ripening mutants

Grierson, D., Purton, M.E., Knapp, J.E. Bathgate, B. (1987). Tomato ripening mutants. In Developmental Mutants in Higher Plants, ed. H. Thomas D. Grierson, pp. 72-94. Cambridge Cambridge University Press. 

Several spontaneous mutants of tomatoes have been Identified specifically as "ripening" mutants. The ripening Inhibitor (rlnl and non-rlpenlng (nor) mutations result In non-cllmacterlc fruits... 

K. C. Gross, Changes in free galactose, myo-inositol and other monosaccharides in normal and non-ripening mutant tomatoes, Phytochemistry, 22 (1983) 1137-1139. 

WB McGlasson, JH Last, KJ Shaw, SK Meldmm. Influence of the non-ripening mutants rin and nor on the aroma of tomato fruit. Hortic Sci 22 632-634, 1987. 

RONEN G, COHEN M, ZAMIR D and HIRSCHBERG J (1999) Regnlation of carotenoid biosynthesis during tomato fruit development expression of the gene for lycopene epsilon cyclase is down regulated during ripening and is elevated in the mutant delta . Plant J, 17, 341-51. 

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. 

Kausch KD, Handa AK. Molecular cloning of a ripening-specific lipoxygenase and its expression during wild-type and mutant tomato fruit development. Plant Physiol 1997 113 1041-1050. 

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... 

Kitagawa, M., Moriyama, T., Ito, H. et al. 2006. Reduction of allergenic proteins by the effect of the ripening inhibitor (rin) mutant gene in an FI hybrid of the rin mutant tomato. Biosci Biotechnol Biochem 70 1227-1233. 

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. 

Seymour, G.B., Harding, S.E., Taylor, A.J., Hobson, G.E. and Tucker, G.A. 1987. Polyuronide solubilization during ripening of normal and mutant tomato fruit, Phytochemistry, 26 1871-1875. 

In tomato two PSY encoding genes have been identified Psy-1 and Psy-2. Psy-1 encodes the fruit-ripening-specific isoform, which has been proved to be the key enzyme in the control of carotenoid biosynthesis [28]. Psy-2 encoded enzyme predominates in green tissues (including mature green fruit) and petals and has no role in carotenoid synthesis in ripening fruit [29, 26]. As an example of the role of this enzyme in carotenoid biosynthesis, a null mutation in Psy-1 in the yellow-flesh (r) mutant arrests carotenoid synthesis [30]. In this mutant, the accumulation of the flavonoid rutin in the fruit skin would lead to the development of yellowish fruits. 

The fruit of the mutant hpl contains enhanced levels of carotenoids and sucrose in comparison to wild-type. Alba et aL demonstrated that fruit-locahzed phytochromes control lycopene accumulation in tomato pericarp during fruit ripening but do not regulate ethylene biosynthesis and many other aspects of fruit ripening in tomato. Their obvious conclusion was that fruit-localized phytochromes are not global regulators of tomato fruit ripening. 

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