活体根毛试验在土荆芥化感胁迫研究中的应用

Assessment of Allelochemical Stress of Chenopodium ambrosioides L.Using in Vivo Root Hair Assay

采用悬空气培养法和活体根毛试验,研究了土荆芥挥发油及其2种主要成分(α-萜品烯和对伞花素)对玉米根毛发育的影响,同时分析了它们诱导根毛凋亡的效应.结果表明,土荆芥挥发油、对伞花素和α-萜品烯具有细胞毒性,可抑制玉米根毛的发育,降低其根毛长度和密度,根毛长度和根毛密度与处理剂量和处理时间呈负相关,挥发油的抑制效应最显著;诱导根毛出现细胞质固缩,FDA染色不着色等凋亡特征.处理12 h时,根毛凋亡率与处理剂量呈正相关,其中挥发油诱导根毛凋亡的效应最强.但随着处理时间延长,不同处理组间、不同剂量与对照之间的差异缩小,当处理时间最长和处理剂量最大时,挥发油诱导的凋亡率小于其余3个处理组,推测出现这种现象的原因是对照组根毛衰老和高剂量挥发油导致根毛坏死.不同处理的化感效应由强到弱依次是挥发油、对伞花素+α-萜品烯、α-萜品烯、对伞花素;α-萜品烯和对伞花素的化感效应为挥发油的60%以上,二者是土荆芥挥发油的主效化感物质.活体根毛试验能较好地反映土荆芥化感潜势,在评估入侵植物化感作用方面具有较好的应用价值.

Aeroponic culture and in vivo root hair assay were used to study the effect of volatile oil from Chenopodium ambrosioides L.and its main components（α-terpinene and cymene） on root hair development and apoptosis.The results showed that volatile oil,α-terpinene and cymene had cytotoxicity on root hair of maize.They reduced length and density of root hair,in which the volatile oil was the most significant,and the root hair length and density had negative correlation with treatment dose and time.The root hair showed apoptosis features,such as cytoplasm condensing and non-staining with FDA（fluorescein diacetate）.The apoptosis rate of root hairs had positive correlation with treatment dose in 12 h,and that of volatile oil was the highest.The gap was gradually narrowing in the treatment groups and different dose groups with control with the increasing of treatment time.While the volatile oil- induced apoptosis rates were less than that of other treatment groups in the longest treatment time and highest treatment dose.It was suggested that the root hairs of control group undergoing senescence and the high dose of volatile oil resulted in root hair necrosis.The allelopathic effects of different treatment groups in turn decrease on volatile oil,α-terpinene ＋ cymene,α-terpinene and cymene.α-tepinene and cymene were main-functional allelochemicals of volatile oil from C.ambrosioides because their allelopathic effects were more than 60%of that of volatile oil.In vivo root hair assay provided a valuable method for assessment of allelopathy in invasive plants,which could better reflect the allelopathic potential of C.ambrosioides.