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Seasonal Changes in the Levels of Some Cellular Components in the Abscission Zone of Coleus Leaves of Different Ages

M. A. CHOUDHURI and S. K. CHATTERJEE
Annals of Botany
New Series, Vol. 34, No. 135 (MARCH 1970), pp. 275-287
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42908770
Page Count: 13
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Seasonal Changes in the Levels of Some Cellular Components in the Abscission Zone of Coleus Leaves of Different Ages
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Abstract

The present study with intact petioles of Coleus of varying ages suggests an involvement of the phenomenon of mobilization with the abscission process. There was a gradual increase in the levels of chlorophyll and nucleic acids and also soluble nitrogen compounds in the proximal tissues with the approach of abscission with a concomitant decrease of these substances in the distal tissues. This increase of metabolites in the proximal tissues was clearer in petioles at the first node than at the fourth node suggesting a lesser degree of metabolic activity of the proximal tissues in older petioles. The change of levels of chlorophyll and nucleic acids and also of soluble nitrogen was more marked in winter than in summer months. The application of NAA to petioles of the third node, just after deblading (i.e. in the auxin-inhibited stage 1), not only stopped the decline of nucleic acid levels (particularly RNA) at the distal tissues but also caused an increase of nucleic acids over the initial levels. This effect was more pronounced in summer than in winter months. If the initially inhibitory concentration of NAA was applied in the auxinpromoted stage 2 of abscission, instead of an increase, there followed a quicker rate of decrease in nucleic acids (particularly RNA). This effect was also more prominent in summer.

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