ISSN:
1432-2285
Keywords:
Action potential
;
Adenine nucleotides
;
Aphid stylet
;
Mimosa
;
Orthophosphate
;
Phloem
;
Sucrose
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Adenosine diphosphate (ADP), adenosine triphosphate (ATP) and orthophosphate were determined in non-stimulated, stimulated and relaxed pulvini of mature Mimosa pudica L. leaves. Additional determinations were made with leaflets, rhachillae, petiole and the stem in the stimulated condition. Results show that the content of adenine nucleotides is approximately twice as high in the pulvini as in the tissues between the pulvini. Orthophosphate, in contrast, occurs at higher concentrations in the connecting tissues than in the pulvini. ATP content is highest in the primary pulvini (0.8 μmol/mg dry wt.) and lowest in the tertiary pulvini. Stimulation causes consumption of ATP with a simultaneous increase in ADP content; however, the response is different in each type of pulvinus. This difference is best expressed in the ATP∶ADP ratio. Stimulation causes the most marked reduction of the ratio (9.5-1.4) in the secondary pulvini which react nyctinastically. Orthophosphate content is reduced by stimulation in all types of pulvini, and is increased during the recovery phase. By using a stylet bundle severed from a feeding aphid by a laser shot as tip for the microelectrode, changes of sieve tube membrane potentials were recorded. The changes of the electropotentials following stimulation show that the sieve tube is the pathway for the transmission of the excitation signal in the form of an action potential.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00196975
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