Respiratory Metabolism in Isolated Orchid Petal Cells

Abstract

SUMMARYA respiratory drift has been demonstrated in cells isolated from petals of Aranda flowers at different stages of development. Tight buds had a respiratory quotient of 0-5; this increased to 0-7 in the first flower and reached 10 in the mature flower. There appeared to be a non-glycolytic pathway contribution in addition to the EMP pathway in tight bud and newly opened flower stages. Carbohydrate metabolism in the mature flower proceeds predominantly via the EMP pathway. Cyanide-insensitive respiration was demonstrated in the tight bud. There was a shift towards cyanide-sensitive respiration as the flower developed.

Ethylene induced cyanide resistant respiration in orchid petal cells

“…Fully opened orchid flowers were strongly inhibited by cyanide as reported earlier [2] and yet they responded dramatically to ethylene . Once developed, the cyanide resistant respiration in orchid flowers can withstand tissue disruption as observed previously [4,10] .…”

“…O2 uptake was measured polarigraphically using a O 2 Hansatech electrode . Treatment of isolated petal cells with potassium cyanide (KCN)(5 mM) and salicylhydroxamic acid (SHAM)(0 .25 mM) were similar to those described previously [2] . All determinations were done in triplicate .…”

“…The occurrence of a cyanide resistant pathway in flowers other than aroids has been reported in carnations [20,21], orchid flowers [2] and roses [14] . Interestingly enough, cyanide resistant respiration was demonstrated in young tight buds of carnation and orchid flowers [2,21] .…”

“…Interestingly enough, cyanide resistant respiration was demonstrated in young tight buds of carnation and orchid flowers [2,21] . There was a shift towards cyanide sensitive respiration as the flower developed such that respiration in fully opened flowers was completely cyanide sensitive .…”

“…There was a shift towards cyanide sensitive respiration as the flower developed such that respiration in fully opened flowers was completely cyanide sensitive . With the onset of senescence, the respiration became cyanide resistant again [2] .…”