Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843.
Plant Physiol. 1991 Apr;95(4):1209-13. doi: 10.1104/pp.95.4.1209.
Abscisic acid (ABA) accumulated in soybean (Glycine max [L.] Merr. cv Williams) hypocotyl elongating regions when seedlings were transferred to low water potential vermiculite (Psi = -0.3 megapascals) even though positive turgor is retained in this tissue. Accumulation of ABA in growing zones could occur from de novo biosynthesis within this tissue or transport from adjacent nongrowing zones. Both growing and nongrowing hypocotyl and root tissues accumulated significant levels of ABA when excised and dehydrated to reduce turgor. Surprisingly, excised growing zones (which experienced no water loss) also accumulated ABA when incubated in darkness for 4 hours at 100% relative humidity and 29 degrees C. Induction of ABA accumulation in the excised elongating region of the hypocotyl was not caused by disruption of root pressure or wounding. While excision of hypocotyl elongating regions induced ABA accumulation, no change in either extensin or p33 mRNA levels was observed. Accumulation of extensin or p33 mRNA required more severe wounding. This suggests that ABA is not involved in the response of these genes in wounded tissue and that wound signals are not causing ABA accumulation in excised tissue. Accumulation of ABA in excised elongating regions was correlated with growth inhibition and a decline in turgor to the yield threshold (Psi;(p) = 0.37 megapascals; R Matyssek, S Maruyama, JS Boyer [1988] Plant Physiol 86: 1163-1167). Inhibiting hypocotyl growth by transferring seedlings to lower temperatures or light did not cause ABA accumulation. We conclude that induction of ABA accumulation in growing zones is more sensitive to changes in turgor than the induction which occurs in mature tissues.
脱落酸（ABA）在将幼苗转移到低水势的珍珠岩（Psi=-0.3 兆帕）时，在大豆（Glycine max [L.] Merr. cv Williams）下胚轴伸长区积累，尽管该组织仍保持正膨压。ABA 在生长区的积累可能来自该组织内的从头生物合成或从相邻的非生长区运输。当切除并脱水以降低膨压时，生长和非生长的下胚轴和根组织都积累了大量的 ABA。令人惊讶的是，当在 100%相对湿度和 29°C 的黑暗中孵育 4 小时时，即使没有水分损失，切除的生长区也会积累 ABA。在切除的伸长区，ABA 的积累不是由根压破坏或创伤引起的。虽然切除下胚轴伸长区会诱导 ABA 积累，但未观察到伸展素或 p33mRNA 水平的变化。伸展素或 p33mRNA 的积累需要更严重的创伤。这表明 ABA 不参与受伤组织中这些基因的反应，而且伤口信号不会导致切除组织中 ABA 的积累。ABA 在切除的伸长区的积累与生长抑制和膨压下降到产量阈值（Psi；（p）=0.37 兆帕；R Matyssek、S Maruyama、JS Boyer [1988] Plant Physiol 86:1163-1167）相关。通过将幼苗转移到较低温度或光照来抑制下胚轴生长不会导致 ABA 积累。我们得出结论，与成熟组织中发生的诱导相比，生长区中 ABA 积累的诱导对膨压变化更为敏感。
