【作者】 袁海永；

【导师】 李颖章；

【作者基本信息】 中国农业大学 ， 植物学， 2005， 硕士

【摘要】 植物细胞对外界生物或非生物的胁迫做出反应时,微丝骨架起了重要的作用。但是对于处于病原攻击的植物细胞中的微丝动态变化还研究不多,特别是当细胞受到的是非物理性攻击时,其微丝骨架的动态变化还不为人了解。本研究报道了大丽轮枝菌毒素诱导下拟南芥悬浮细胞中微丝骨架的动态变化。细胞在低浓度大丽轮枝菌毒素作用下,细胞中的微丝骨架从细胞膜下到核周围陆续被降解,但随后膜下周质微丝骨架可自动恢复。表明,核周微丝可能比周质微丝对毒素的作用抗性更强。当细胞用高浓度毒素处理时,细胞中的微丝骨架被破坏的速度更快,而且微丝骨架不能自动恢复。除微丝骨架发生变化外,高浓度毒素处理的细胞核中核仁也出现了变化:在处理早期,细胞核有一个较大的并且是环状的核仁,颜色较淡;在后期一个细胞核里面出现两个以上的较小的核仁,并且随着时间的推移,核仁的亮度和数目逐渐增加。在核仁能够看见以前,即核仁开始着色以前将毒素除去,可以使已经破坏的周质微丝骨架恢复过来。这些结果说明,微丝骨架参与了拟南芥悬浮细胞针对大丽轮枝菌毒素的抗性反应,并且在其中起了重要的作用,而核仁的变化也可能是受到大丽轮枝菌毒素侵袭的细胞的特性,这种核仁的变化伴随着细胞的死亡。这种类型的细胞死亡可能是程序性死亡。更多还原

【Abstract】 In plant cells, actin cytoskeleton plays important roles in response to biotic and abiotic stresses. However, little has been known about the dynamics of actin cytoskeleton when cells are attacked by unphysical attacks from some stress factors such as elicitors. We report here that the toxin of Verticillium dahliae (VD-toxin) induced the changes of actin filaments in Arabidopsis suspension-cultured cells. When the cells were treated with low concentration VD-toxin, F-actin arrays were disrupted ordinally from cortex to nucleus-around, and then came the automatic recovery of them. The actin filaments in the perinuclear region showed more resistance to VD-toxin than the cortical ones. In contrast, when the cells were treated with high concentration VD-toxin, F-actin arrays were disrupted more severely and the disrupted actin cytoskeleton could not be recovered spontaneously. The treatment of high concentration VD-toxin on cells also induced the changes of nucleoli. At the early stages of the treatment, a nucleus had a single ring-shaped nucleolus. At the later stages, multiple smaller and brighter nucleoli emerged in a single nucleus. Disrupted actin cytoskeleton could be recovered by removal of the VD-toxin before the nucleoli were dyed. All these results showed that the actin cytoskeleton plays important roles in the early defense responses against VD-toxin in Arabidopsis suspension cells. The changes of the nucleoli induced by VD-toxin may be important characteristics that were accompanied by resistance-related cell death.更多还原