van der Weerd L, Claessens M M, Ruttink T, Vergeldt F J, Schaafsma T J, Van As H
Laboratory of Biophysics, Wageningen University, Dreyenlaan 3, 6703 HA Wageningen, The Netherlands.
J Exp Bot. 2001 Dec;52(365):2333-43. doi: 10.1093/jexbot/52.365.2333.
The effect of osmotic stress (-0.35 MPa) on the cell water balance and apical growth was studied non-invasively for maize (Zea mays L., cv. LG 11) and pearl millet (Pennisetum americanum L., cv. MH 179) by (1)H NMR microscopy in combination with water uptake measurements. Single parameter images of the water content and the transverse relaxation time (T(2)) were used to discriminate between the different tissues and to follow the water status of the apical region during osmotic stress. The T(2) values of non-stressed stem tissue turned out to be correlated to the cell dimensions as determined by optical microscopy. Growth was found to be strongly inhibited by mild stress in both species, whereas the water uptake was far less affected. During the experiment hardly any changes in water content or T(2) in the stem region of maize were observed. In contrast, the apical tissue of pearl millet showed a decrease in T(2) within 48 h of stress. This decrease in T(2) is interpreted as an increase in the membrane permeability for water.
通过¹H NMR显微镜结合水分吸收测量，对玉米（Zea mays L.，品种LG 11）和珍珠粟（Pennisetum americanum L.，品种MH 179）非侵入性地研究了渗透胁迫（-0.35 MPa）对细胞水平衡和顶端生长的影响。利用含水量和横向弛豫时间（T(2)）的单参数图像来区分不同组织，并跟踪渗透胁迫期间顶端区域的水分状态。结果表明，未受胁迫的茎组织的T(2)值与光学显微镜测定的细胞尺寸相关。发现两种植物的生长均受到轻度胁迫的强烈抑制，而水分吸收受影响较小。在实验过程中，几乎未观察到玉米茎区域的含水量或T(2)有任何变化。相反，珍珠粟的顶端组织在胁迫48小时内T(2)降低。T(2)的这种降低被解释为水的膜通透性增加。
