肉桂酸和咖啡酸对莴苣生长的化感作用及其机理研究

Allelopathic Effect and Mechanism of Cinnamic Acid and Caffeic Acid on the Growth of Lettuce

该研究以莴苣为受体植物,分析了酚酸类化感物质肉桂酸和咖啡酸对莴苣幼苗生长的活性效应及其作用机理,以揭示酚酸类化合物的化感作用机制。结果显示:(1)不同浓度的肉桂酸均对莴苣幼苗根长、茎长及鲜重产生明显的抑制作用,当肉桂酸的浓度为1 000μmol/L时其对莴苣幼苗根长、茎长及鲜重的抑制率分别达到了89%、74%和49%;咖啡酸对莴苣幼苗根长和茎长均表现出低浓度(0.1、1.0和10μmol/L)促进、高浓度(100和1 000μmol/L)抑制的活性作用模式,且高浓度下肉桂酸对幼苗生长的抑制作用明显强于咖啡酸。(2)较低浓度(0.1、1.0和10μmol/L)的肉桂酸和咖啡酸对莴苣根尖细胞活力均无明显影响;高浓度(100和1 000μmol/L)的肉桂酸和咖啡酸使莴苣根尖细胞的死亡数明显增加。(3)低浓度(0.1和1.0μmol/L)的肉桂酸和较低浓度(0.1、1.0和10μmol/L)的咖啡酸对莴苣根部的活性氧积累均无明显影响;当肉桂酸处理浓度大于10μmol/L及咖啡酸处理浓度大于100μmol/L时,随着浓度的升高莴苣根部活性氧的积累大量增加。研究表明,一定浓度的肉桂酸和咖啡酸均能够诱导莴苣体内活性氧的产生和积累,并降低幼苗根尖细胞的活力,进而影响莴苣幼苗的生长发育,且肉桂酸的生长抑制作用明显强于咖啡酸。

In this paper,we investigated the allelopathic effects of cinnamic acid and caffeic acid and their phytotoxic mechanism on lettuce seedlings,in order to reveal the mechanism of allelopathy by phenolic acids.The results showed that：（1）root length,shoot length and fresh weight of lettuce seedlings were all obviously inhibited by cinnamic acid at different concentrations,and the inhibition rate of root length,shoot length and fresh weight at concentration of 1 000μmol/L was 89%,74% and 49%,respectively.Root length and shoot length of lettuce seedlings both were promoted at low concentration（0.1,1.0and 10μmol/L）and inhibited at high concentration（100and 1 000μmol/L）by caffeic acid.Besides,the growthinhibition of cinnamic acid on lettuce seedlings was obviously stronger than that of caffeic acid at high concentration.（2）Cinnamic acid and caffeic acid both had no significant effect on cell viability in lettuce root tips at low concentration（0.1,1.0and 10μmol/L）.High concentration（100and 1 000μmol/L）of cinnamic acid and caffeic acid both significantly increased the number of dead cells.（3）Low concentration of cinnamic acid（0.1and 1.0μmol/L）and caffeic acid（0.1,1.0and 10μmol/L）both had no significant effect on the accumulation of reactive oxygen species（ROS）.When the concentration of cinnamic acid was over 10μmol/L and the concentration of caffeic acid was over 100μmol/L,the accumulation of ROS increased rapidly with the increasing of concentration.ROS was induced and accumulated in lettuce seedlings under the stress of cinnamic acid and caffeic acid,which leaded to the reduction of cell viability and finally affected the growth and development of lettuce seedlings.Furthermore,the inhibition effect of cinnamic acid was significantly stronger than that of caffeic acid.