Hasenstein K H, Rayle D
Department of Botany, San Diego State University, California 92182, USA.
Plant Physiol. 1984 Sep;76(1):65-7. doi: 10.1104/pp.76.1.65.
According to the chemiosmotic polar diffusion hypothesis, auxin pulse velocity and basal secretion should increase with decreasing cell wall pH. Experiments were designed to test this prediction. Avena coleoptile sections were preincubated in either fusicoccin (FC), cycloheximide, pH 4.0, or pH 8.0 buffer and subsequently their polar transport capacities were determined. Relative to controls, FC enhanced auxin (IAA) uptake while CHI and pH 8.0 buffer reduced IAA uptake. Nevertheless, FC reduced IAA pulse velocity while cycloheximide increased velocity. Additional experiments showed that delivery of auxin to receivers is enhanced by increased receiver pH. This phenomenon was overcome by a pretreatment of the tissue with IAA. Our data suggest that while acidic wall pH values facilitate cellular IAA uptake, they do not enhance pulse velocity or basal secretion. These findings are inconsistent with the chemiosmotic hypothesis for auxin transport.
根据化学渗透极性扩散假说，生长素脉冲速度和基础分泌应随着细胞壁pH值的降低而增加。设计了实验来检验这一预测。将燕麦胚芽鞘切段预先在壳梭孢菌素（FC）、环己酰亚胺、pH 4.0或pH 8.0缓冲液中孵育，随后测定其极性运输能力。相对于对照组，FC增强了生长素（IAA）的吸收，而CHI和pH 8.0缓冲液降低了IAA的吸收。然而，FC降低了IAA脉冲速度，而环己酰亚胺提高了速度。额外的实验表明，受体pH值的升高会增强生长素向受体的传递。用IAA对组织进行预处理可克服这一现象。我们的数据表明，虽然酸性细胞壁pH值有利于细胞对IAA的吸收，但它们不会提高脉冲速度或基础分泌。这些发现与生长素运输的化学渗透假说不一致。
