Department of Botany, University of North Carolina, 27514, Chapel Hill, North Carolina, USA.
Planta. 1974 Mar;119(1):27-37. doi: 10.1007/BF00390819.
The effect of pH on the elongation rate of 2-mm-long subapical segments from corn roots (Zea mays L.) was investigated under aerobic (O2) and anaerobic (N2) conditions using a specially designed apparatus. The maximum elongation rate was obtained with a citrate-phosphate buffered solution of pH 3.4 or a non-buffered solution of pH 3.2. Acid stimulation of the elongation rate occurred in the zone of maximum elongation in the root, the 3 mm region 1 mm behind the apex. The acid response can be rapidly and repeatedly reinitiated by alternating between pH 4.0 and 7.0 media. Low pH can increase the elongation rate under N2 conditions, but the response is only ca. 50% that of the increase observed under O2 conditions. Reinitiation of the acid response does not occur when solutions are gassed with N2. The data suggest that the response of root segments to H ions is similar to that reported in the literature for shoot tissue. However, the magnitude of the root response is much higher than that of shoot tissue. Also, there is evidence that some aspects of the mode of action of H ions on wall loosening in root tissue may differ from that in shoot tissue. Corn root segments, though lacking a cuticle, do not respond to low pH in the manner reported for peeled stem tissue, the cuticle and epidermis of which have been removed. For these reasons rapid-growth responses of roots and shoots may not be strictly comparable.
采用专门设计的设备，在有氧（O2）和无氧（N2）条件下，研究了 pH 值对玉米（Zea mays L.）根尖下 2mm 长亚顶端段伸长率的影响。在 pH3.4 的柠檬酸盐-磷酸盐缓冲溶液或 pH3.2 的非缓冲溶液中，可获得最大伸长率。在根尖后 1mm 的最大伸长区，即 3mm 区域，酸刺激伸长率。酸响应可以通过在 pH4.0 和 7.0 介质之间交替快速且反复重新启动。在 N2 条件下，低 pH 值可以增加伸长率，但响应仅约为 O2 条件下观察到的增加的 50%。用 N2 对溶液进行充气时，酸响应不会重新开始。数据表明，根段对 H 离子的反应与文献中报道的芽组织的反应相似。然而，根反应的幅度远高于芽组织。此外，有证据表明，H 离子对根组织壁松弛作用的作用方式的某些方面可能与芽组织不同。玉米根段虽然没有角质层，但不会像去皮茎组织那样对低 pH 值作出反应，因为已经去除了其角质层和表皮。由于这些原因，根和芽的快速生长反应可能不完全可比。
