Benzyladenine induced stimulation of 2 components of chlorophyll formation in etiolated cucumber cucumis sativus cultivar aonagajibai cotyledons

Dei, M.

Physiologia Plantarum 62(4): 521-526

1984


ISSN/ISBN: 0031-9317
DOI: 10.1111/j.1399-3054.1984.tb02793.x
Accession: 004819967

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Abstract
Excised etiolated cotyledons of cucumber (C. sativus L. cv. Aonagajibai) were continuously irradiated under various intensities of white light. The rate of chlorophyll (Chl) formation during the lag phase reaches a plateau at fluence rates above 1.4 .mu.mol m-2 s-1. This is true in both water-control and benzyladenine (BA)-pretreated cotyledons. In cotyledons pretreated for 14 h with BA in darkness (in which case, Chl formation is stimulated by BA during both the lag and the steady-state phases), the increase in the steady-state rate of Chl formation with increasing light intensity is stimulated compared to that of the water control over the range of fluence rates, 0.25-43 .mu.mol m-2 s-1. In cotyledons pretreated for 6 h with BA in darkness (only Chl formation during the lag phase is stimulated), only an increase in fluence rate from 0.25 to 1.4 .mu.mol m-2 s-1 causes a higher increase in the Chl formation in the BA-treated cotyledons than in the water control. The time course of Chl formation shows that the BA-induced late-appearing effect (stimulation of the steady-state rate) is almost absent at low intensity illumination, but the BA-induced fast-appearing effect (elimination of the lag phase) is effective at all intensities. The Chl-forming process apparently consists of 2 components, whose periods of operation or light-intensity requirements are different. BA stimulates the rates of the respective components in both the fast and the late-appearing effects.

Benzyladenine induced stimulation of 2 components of chlorophyll formation in etiolated cucumber cucumis sativus cultivar aonagajibai cotyledons