Respiration of Orchid Flower Mitochondria

A high percentage of intact mitochondria was isolated from Aranda flower petals. The state 3 and state 4 respiration of mitochondria isolated from flowers at different stages of development were different. The ADP/O (equivalent to P/O) and respiratory control (RC) ratios also varied when different substrates were added. Highest state 3 and state 4 rates were observed when malate and succinate or malate, succinate, and NADH were the substrates. Mature flower mitochondria have high P/O and RC ratios. Bud mitochondria, in contrast, have low P/O and RC ratios but can oxidize NADPH faster. A high degree of cyanide resistance and rotenone insensitivity was observed in bud mitochondria. The relationship of these findings to the need for energy and metabolic intermediates for bud growth in early stages of flower development is discussed.