Abscisic acid cycle

Physiologically, violaxanthin is an important component of the xanthophyU cycle a high light stress-induced de-epoxidation of the violaxanthin pool to the more photoprotective zeaxanthin is mediated by violaxanthin de-epoxidase (VDE). Violaxanthin and neoxanthin, an enzymatically (NXS)-produced structural isomer, are the precursors for the abscisic acid (ABA) biosynthetic pathway (Figure 5.3.1, Pathway 4 and Figure 5.3.2). In non-photosynthetic tissues, namely ripe bell peppers, antheraxanthin and violaxanthin are precursors to the red pigments, capsanthin and capsorubin, respectively (Figure 5.3.3B). 

Thompson, A. J., A. C. Jackson et al. (2000a). Abscisic acid biosynthesis in tomato Regulation of zeaxanthin epoxidase and 9-cw-epoxycarotenoid dioxygenase mRNAs by light/dark cycles, water stress and abscisic acid. Plant Mol. Biol. 42(6) 833-845. 

There are few specific studies of the effects of gibberellins, ethylene, abscisic acid, and other growth regulators on the cell cycle. While these substances have effects on division in some instances, evidence connecting these effects to specific steps of the cell cycle is generally lacking. 

Friedberg SH, Davidson D (1970) Duration of S phase and cell cycles in diploid and tetraploid cells of mixoploid meristems. Exp Cell Res 61 216-218 Fuchs Y, Lieberman M (1968) Effects of kinetin, lAA, and gibberellin on ethylene production, and their interactions in growth of seedlings. Plant Physiol 43 2029-2036 Gaither DH, Lutz DH, Forrence LE (1975) Abscisic acid stimulates elongation of excised pea root tips. Plant Physiol 55 948-949... 

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