Comparison of pH Changes and Elicitor Induced Production of Glyceollin Isomers in Soybean Cotyledons

Abstract

During the incubation of soybean cotyledons with Pmg-elicitor for 22 hours the pH of the diffusion droplets increases from 7.2 to 8.3. This pH-shift is a precondition for the formation of the typical red colour of the diffusion droplet. After inhibiting the pH-shift by the use of 100 mм phosphate or Tris buffer instead of 10 mм buffer as solvent for the elicitor, the red colour is no longer formed with the exeption of 100 mM Ammediol buffer. However, the normal pattern of pterocarpan induction can be measured in the absence of the red colour in the diffusion droplet. Tris and Ammediol buffers exhibited a smaller pterocarpan induction as compared to phosphate buffer as solvent for the Pmg-elicitor.

31P NMR Study of Elicitor Treated Phaseolus vulgaris Cell Suspension Cultures

“…The pH of diffusion droplets increased from 7.2 to 8.3 after 22 h when soybean cotyledons were incubated with a fungal elicitor. This shift in pH was a precondition for the induced production of glyceollin isomers (17), which might indicate that the change in pH in P. vulgaris is also involved in the initial stages of phytoalexin formation.…”

“…It was suggested that changes in the intracellular pH (17), intracellular phosphate concentrations (24), or the membrane potential (19) tions and pH observed in plant cells after elicitor addition (24). In that study the plant cells were not aerated during the NMR measurements.…”

Effect of Elicitation and Changes in Extracellular pH on the Cytoplasmic and Vacuolar pH of Suspension-Cultured Soybean Cells

“…Rapid changes in cytoplasmic pH have been implicated as a mechanism of signal transduction in a wide variety of biological systems (4,10,13,20,21). Although the occurrence of such pH transitions under physiological conditions has been questioned recently in animal cells (6,9,30), there is still substantial evidence for their occurrence during the defense response in plants (4,13,20,21,27).…”

“…Although the occurrence of such pH transitions under physiological conditions has been questioned recently in animal cells (6,9,30), there is still substantial evidence for their occurrence during the defense response in plants (4,13,20,21,27). This defense response, as it is currently understood, involves a rather global change in cell biochemistry encompassing transitions in pathways as diverse as phytoalexin synthesis (7), callose formation (5,14), biosynthesis of lignin-like material (5,22), hydroxyproline-rich protein synthesis (5), release of H202 (2), production of hydrolytic enzymes (5,27), synthesis of protease inhibitors (5), and hypersensitive cell death (4).…”

“…680 of these pathways are biochemically unrelated, a pervasive signal such as a change in cytoplasmic pH would seem to be an efficient means of initiating them from a single stimulus. Therefore, it is not surprising that the possible involvement of a rapid intracellular pH change during elicitation has already received considerable attention (4,13,20,21,29).…”