Auxin and hydrogen ion actions on light-grown pea epicotyl segments II. Effect of hydrogen ions on extension of the isolated epidermis

摘要

Isolated epidermis treated differently, i.e. fresh, frozen-thawed and methanol-treated, was subjected to extension tests under a tension of 2×107dyne/cm2in buffer solution at different pH values.(1) Fresh and frozen-thawed epidermis extended in response to buffer solution at pH values lower than 5.5. Half of the maximum extension was achieved at pH 4.5.(2) Epidermis boiled in methanol or treated with pronase did not extend in response to pH 4.5. Low temperature reduced the rate of extension of fresh or frozen-thawed epidermis induced by pH 4.5.(3) Pretreatment of the epidermis with 0.1%deoxycholate for 30 min did not inhibit acid-induced extension.(4) Nojirimycin, 3×10-3M, added to the buffer solution inhibited acid-induced extension.(5) Epidermis peeled off from segments which had been treated with cycloheximide for 90 min, extended in response to pH 4.5.(6) Methanol-treated epidermis did not extend at pH 4.5, but extended somewhat at pH 3.0.These results suggest that hydrogen ions induce cell wall loosening, possibly through activation of wall-bound enzyme