Cell division fruit development

In plants, aliphatic di- and polyamines have been implicated in many processes including rapid cell division, fruit development, stress response and senescence (Evans and Malmberg, 1989 Galston and Kaur-Sawhney, 1995). Amine oxidases catalyse the eatabolism of biogenic amines and hence could be involved in regulating sueh eellular processes. It is eonve-nient to separate discussion of the roles of the copper-containing idiamine... 

Developing fruits are rich sources of cytokinins, which are found in tissues where rapid cell-divisions are occurring, and are considered to play an important role in the regulation of cell division in fruit.397,424 Letham424 concluded that shape of the apple at maturity probably depends upon the balance between gibberellins and cytokinins in the immature fruit, and that apple varieties differ in their response to these compounds. 

Figure 3 shows the hypothetical kinetics of growth, respiration and relative hormone levels in a climacteric fruit at different stages of its life cycle. Hypothetical hormone levels during development and ripening have been speculated on before (13). The rationale for this outline is based on the known influences of the various hormones on cell division,... 

In nature, auxins are produced in apical and root meristems, young leaves, seeds and developing fruits, and their main functions are cell elonj tion and expansion, suppression of lateral buds, etc. (Opik RoUe, 2005). In somatic embryogenesis this is considered one of the most important elements producing cell polarity and asymmetrical cell division. In general, relatively high auxin concentrations (2,4-D, lAA, etc.) favor callus formation and the induction process (cell polarity). Afterwards, when the induction stage has been achieved, it is necessary to reduce or eliminate the auxins in order to initiate the bilateral symmetry and the expression of the somatic embryos. 

Considine, J. A. Knox, R.B. (1981). Tissue origins, cell lineages and patterns of cell division in the developing dermal system of the fruit of Vitis vinifera L. Planta, Vol. 151, No. 5, (May 1981), pp. 403-412, ISSN 0032-0935... 

The cytokinins are extremely potent as little as 5 X 10 M 6-(4-hydroxy-3-methyl-frans-2-butenylamino) purine can be detected by some bioassay systems. They have a wide variety of actions in plants, including promotion of cell division, delay of senescence, and resistance to adverse conditions. They affect plant metabolism, organelle development, and fruit and flower formation. Unfortunately, their basic mechanisms of action are not known. 

Auxins control many aspects of plant growth and development. Physiological processes such as cell elongation, cell division, differentiation, tropisms, rooting, fruit development and abscission are influenced by auxin [ 16,50,62]. However, the mechanism by which this hormone regulates diverse physiological processes is... 

The next phase of fruit development starts with the double fertilization. During this phase the endosperm is formed. The embryo also grows by dividing. Evidently this is associated with active cell division, which takes place in the fruit tissue. Perhaps initially the regulating hormones come from the endosperm but in later stages they are derived from the embryo. In addition to lAA and gibberellins cytokinins in particular seem to be involved, as was shown by analyses of some fruits during this phase. 

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