Atmungswege bei vernarbenden und proliferierenden Gewebefragmenten der Kartoffelknolle

Abstract

The typical wound respiration drift (O2 und CO2) of 1 mm disks, which amounts to 6 times the values measured immediately after derepression, develops only if cicatrization takes place, but never in proliferating or non-proliferating tissues without suberin biosynthesis. The respiration rate of the latter is merely approximately doubled during the first 8 hours and maintains a steady state level continuously for 6 days. The respiratory drift is not affected by methods of tissue preparation and CO2-concentration per se but only depends on the induction or inhibition of suberin synthesis.Cyanide inhibition experiments evidently indicate an electron transfer mechanism by suberizing cells during the first 48 hours which is linked to cytochrome oxidase activity to a considerable extent, whereas proliferating tissue respiration nearly quantitatively follows a different pathway of cyanide-resistant terminal oxidation.Malonate inhibition experiments show the total respiration of proliferating tissue to be resistant, which therefore is bound to the activity of a pathway different from the tricarboxylic acid cycle. Predominantly the action of the pentose-phosphate-shunt must be responsible for energy producing processes and metabolism which finally regulate cell proliferation as well as cell division. Malonate sensitive respiration, that is TCA-cycle activity, is developed only in periderm-forming tissue. Its volume is shown to be in congruence with the amount of "induced respiration" evolved after 8 hours and is responsible for the typical maximum curve. In contrast the resistant basal level is in congruence with the total respiration volume of proliferating disks.The results indicate a direct relationship between increased TCA-cycle activity and suberin synthesis rather than a relationship between TCA-cycle and cellular processes such as protein synthesis, cell division or elongation, as emphasized by other authors.

The Cyanide-Resistant, Alternative Path in Higher Plant Respiration

“…Whereas CO2 is normally considered an ethylene antagonist (13), in this case, as with the overcoming of thermodor mancy in lettuce seed (51) and the activation of pea cotyledon ATPase (70), ethylene and CO2 act synergistically. The incentive for CO2 utilization in the context under discussion stemmed from the observations of Lange (58) on the effect of CO2 on the elicitation of CN resistance in aging potato slices, reinforced by the report of McCaig & Hill (73) on the effect of CO2 on the development of CN resistance in wheat seedlings. Lange showed that potato slices aged in 10% CO2 in moist air fully developed a CN-stimulated induced respiration in 12 h, whereas slices aged in aerated solution in conventional fashion became 85% CN resistant in 24 h, and fully eN resistant in 48 h. Of more importance, however, slices aged in high CO2 formed proliferating callus, whereas conventionally aged slices formed ter minal periderm.…”

Ethylene and wound‐induced cyanide‐resistant respiration climaxes in potato: The synergistic role of CO2 and the selective role of lycorine

“…Guided by observations by Lange (1970) that atmospheres enriched in CO2 favor the development of cyanide resistance in potato slices aged in moist air, we discovered that 10% CO, added to a mixture of ethylene in O, either accentuates the ethylene effect in conditioned tubers (Day et al 1978), or substitutes for the conditioning process (see below). The synergistic effect of Oj on ethylene action has been amply demonstrated (Chin andFrenkei 1977, Theologis andLaties 1982), and attention in what follows centers on the role of CO,.…”

“…2). Where slicing is concerned, CO, diverts the development of a terminal periderm in slices to proliferating callus, at the same time that it limits the extent of the wound-induced respiration and hastens the restoration of CN" resistance (Lange 1970). In tubers, ethylene alone creates tubers that yield CN"-resistant fresh siices in conjunction with a respiration climax when conditioned tubers are treated soon after harvest.…”

The Influence of Aging Conditions on the Short Term Growth of Green Pea Stem Segments

“…Aging presumably dissipates (by metabolism, transport, diffusion, and dilution) endogenous growth regulating substances. It also reduces problems associated with the response of tissues to cutting or tactile stimuli, as wounding or mechanical stimulation cause, in some tissues, a transitory acceleration of growth (4, 6) and respiration (1,8).We have investigated the growth effects of various conditions (both prior to and during growth measurements) on light-grown pea stem segments. With such information, the effects of subsequent treatments can be ascribed with greater confidence to the experimental treatment, not to endogenous conditions.…”

“…Aging presumably dissipates (by metabolism, transport, diffusion, and dilution) endogenous growth regulating substances. It also reduces problems associated with the response of tissues to cutting or tactile stimuli, as wounding or mechanical stimulation cause, in some tissues, a transitory acceleration of growth (4,6) and respiration (1,8).…”