Volobueva O V, Khokhlova L P, Velikanov G A, Opanasiuk O A
Kazan' State University, and Kazan' Institute of Biochemistry and Biophysics, Kazan' Research Center RAS, Kazan'.
Tsitologiia. 2001;43(5):477-82.
In roots of 5-6-day old seedlings of three cultivars of the winter wheat, varying in drought-resistance: Bezostaya 1 (low resistant), Mironovskaya 808 (resistant), and Albidum 114 (highly resistant) water permeability of two transport channels of plasmodesmata was studied at the action of cytochalasin B, which is known to inhibit polymerization of cytoskeleton actin filaments, by a pulse method of NMR, on the background of increasing water loss in the seedlings. It has been found that the registered coefficients of water self diffusion, two of which (D2 and D3) depend on the water permeability of different transport channels of plasmodesmata, differ in opposite directions. This may suggest that in roots of drought-resistant plants, after a moderate water loss, a diffusive water flow through the cytoplasmic symplast increases (demonstrated by an increase of D2), while that through the vacuolar symplast decreases (seen by an increase of D3). After a high water loss in seedlings, we noticed an even greater increase in water permeability of the cytoplasmic symplast, and a decrease in water permeability of the vacuolar symplast, however, in the roots of low resistant cultivars these changes were poorly expressed, if at all. Under stress-less conditions cytochalasin B would result in an increased water transport through the cytoplasmic channel of plasmodesmata due apparently to a destruction of their actin-myosin sphincters. Both weak and average degrees of water loss would strengthen the cytochalasin B exerted influence on plasmodesmal water conductance, that may testify to a synergetic action of these two factors. After a significant water loss this action was kept only partially, because the inhibitor, on blocking the cytoplasmic channel, did increase at the same time the effect of water stress, limiting water flows through the vacuolar symplast and, simultaneously, raising the water inflow to the apoplast.
在三个抗旱性不同的冬小麦品种（别佐斯塔亚1号，低抗性；米罗诺夫斯卡亚808号，抗性；阿尔比杜姆114号，高抗性）5 - 6日龄幼苗的根中，通过脉冲核磁共振法，在幼苗水分流失增加的背景下，研究了细胞松弛素B作用下胞间连丝两个运输通道的水渗透性。细胞松弛素B已知可抑制细胞骨架肌动蛋白丝的聚合。研究发现，记录的水自扩散系数，其中两个（D2和D3）取决于胞间连丝不同运输通道的水渗透性，其变化方向相反。这可能表明，在抗旱植物的根中，适度水分流失后，通过细胞质共质体的扩散水流增加（表现为D2增加），而通过液泡共质体的水流减少（表现为D3增加）。幼苗大量水分流失后，我们注意到细胞质共质体的水渗透性进一步大幅增加，液泡共质体的水渗透性降低，然而，在低抗性品种的根中，这些变化即使有也表现得很不明显。在无胁迫条件下，细胞松弛素B显然会导致通过胞间连丝细胞质通道的水运输增加，这可能是由于其肌动蛋白 - 肌球蛋白括约肌被破坏。轻度和中度水分流失都会增强细胞松弛素B对胞间连丝水导率的影响，这可能证明这两个因素具有协同作用。大量水分流失后，这种作用仅部分保留，因为抑制剂在阻断细胞质通道的同时，确实增加了水分胁迫的影响，限制了通过液泡共质体的水流，同时增加了向质外体的水流入量。
