Yuan Hai-Yong, Yao Lin-Lin, Jia Zhi-Qi, Li Yun, Li Ying-Zhang
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China.
Protoplasma. 2006 Nov;229(1):75-82. doi: 10.1007/s00709-006-0154-6. Epub 2006 Oct 6.
In plant cells, cytoskeletons play important roles in response to biotic and abiotic stresses. However, little is known about the dynamics of cytoskeletons when cells are attacked by unphysical stress factors such as elicitors and toxins. We report here that the toxin of Verticillium dahliae (VD toxin) induced changes of microfilaments (MFs) and microtubules (MTs) in Arabidopsis thaliana suspension-cultured cells. When cells were treated with a low concentration of VD toxin, MFs were disrupted ordinally from the cortex to the perinuclear region, and then recovered spontaneously; but the MTs persisted. The MFs in the perinuclear region showed more resistance to VD toxin than the cortical ones. In contrast, when cells were treated with a high concentration of VD toxin, MFs and MTs were disrupted sooner and more severely and did not recover spontaneously. Treatments with high concentrations of VD toxin also induced changes of nucleoli. At the early stages of treatment, a nucleus had a single ring-shaped nucleolus. At the later stages, multiple smaller and more brightly fluorescing nucleoli emerged in a single nucleus. Disrupted MFs could be recovered by removing the VD toxin before the ring-shaped nucleoli appeared. All these results showed that MFs and MTs play important roles in the early defense responses against VD toxin in Arabidopsis suspension cells. The cytoskeletons may be used as sensors and effectors monitoring the defense reactions. The changes of nucleoli induced by VD toxin should be important characteristics of cell death.
在植物细胞中，细胞骨架在应对生物和非生物胁迫时发挥着重要作用。然而，当细胞受到诸如激发子和毒素等非物理胁迫因素攻击时，关于细胞骨架的动态变化却知之甚少。我们在此报告，大丽轮枝菌毒素（VD毒素）可诱导拟南芥悬浮培养细胞中微丝（MFs）和微管（MTs）发生变化。当用低浓度的VD毒素处理细胞时，微丝从皮层到核周区域依次被破坏，然后自发恢复；但微管则持续存在。核周区域的微丝比皮层微丝对VD毒素表现出更强的抗性。相反，当用高浓度的VD毒素处理细胞时，微丝和微管更快、更严重地被破坏，且不会自发恢复。高浓度VD毒素处理还会诱导核仁发生变化。在处理初期，细胞核有一个单一的环形核仁。在后期，单个细胞核中会出现多个更小且荧光更强的核仁。在环形核仁出现之前去除VD毒素，被破坏的微丝可以恢复。所有这些结果表明，微丝和微管在拟南芥悬浮细胞对VD毒素的早期防御反应中起重要作用。细胞骨架可能用作监测防御反应的传感器和效应器。VD毒素诱导的核仁变化应是细胞死亡的重要特征。
