绿原酸对莴苣生长的化感作用及其机理研究

Allelopathic Effect and Mechanism of Chlorogenic Acid on the Growth of Lettuce

酚酸类化合物是一类重要的化感物质,广泛存在于农作物等植物体内以及耕作土壤中,与植物的化感效应以及连作障碍密切相关。该研究以蔬菜类植物莴苣为受体,采用植物细胞和生理学方法,分析酚酸类化感物质绿原酸抑制莴苣生长的活性效应及其作用机理,以揭示绿原酸介导的化感作用及连作障碍机制。结果显示:(1)绿原酸对莴苣的根长、茎长以及鲜重等生长指标均表现出低浓度(0.1和1.0μmol/L)促进、高浓度(10、100和1 000μmol/L)抑制的活性作用模式,其在10μmol/L及以上浓度时对根长和鲜重具有显著抑制作用,但在各浓度下对莴苣茎长无显著影响。(2)绿原酸处理后,莴苣根尖细胞分裂指数明显下降,随处理浓度的升高,各分裂时期的细胞比例也显著降低,导致细胞分裂过程受阻。(3)较低浓度(0.1、1.0和10μmol/L)绿原酸对莴苣根尖细胞活力无明显影响,较高浓度绿原酸(100和1 000μmol/L)使莴苣根尖死细胞显著增多,根尖端绝大部分细胞失去活力。(4)DHE荧光染色显示,与对照相比,低浓度(0.1和1.0μmol/L)绿原酸对莴苣根部的活性氧积累无明显影响,当绿原酸处理浓度大于10μmol/L时,随处理浓度升高莴苣根部的活性氧积累明显大量增多。研究表明,绿原酸能够诱导莴苣体内活性氧产生并积累,从而导致莴苣细胞分裂受阻、细胞活力降低,最终影响莴苣幼苗的生长发育。

Phenolic acids are one kind of important allelochemicals,which generally exist in crops and vegetables,as well as their cultivated soils.These metabolites are involved in plant allelopathic effect and continuous cropping obstacles.In this paper,we investigated the allelopathic effect of chlorogenic acid and its phytotoxic mechanism on lettuce seedlings by plant cell and physiology methods,in order to reveal the allelopathy and continuous cropping obstacles mediated by chlorogenic acid.The results showed that：（1）Root length,shoot length and fresh weight of lettuce seedlings were promoted by chlorogenic acid at low concentrations（0.1 and 1 μmol/L） and were inhibited at high concentrations（10,100 and 1 000 μmol/L）.Chlorogenic acid displayed significant inhibitory effects on root length and fresh weight of lettuce at concentrations of 10 μmol/L and more.However,shoot growth of lettuce was not significantly inhibited by chlorogenic acid at each concentrations used.（2）After treated by chlorogenic acid,the mitotic index of lettuce root tips was significantly decreased,and with the concentration of chlorogenic acid increasing,the proportion of cells in each mitotic phase was also significantly reduced,resulted in arrest of cell division.（3）Under low concentrations（0.1,1.0 and 10 μmol/L）,chlorogenic acid had no significant effect on cell viability in lettuce root tips.However,high concentrations of chlorogenic acid（100 and 1 000 μmol/L） significantly increased the number of dead cells,and caused losing of cell vitality in lettuce root tips.（4）Fluorescence staining of DHE showed that low concentrations（0.1 and 1.0 μmol/L） of chlorogenic acid had no significant effects on the accumulation of reactive oxygen species（ROS） compared with the control.However,when the concentration of chlorogenic acid reached 10 μmol/L,a lot of ROS accumulated in lettuce roots with concentration increasing.These results indicated that under the stress of chlorogenic acid,ROS in lettuce was induced and then accumulated.Furthermore,the cell division and viability were inhibited,resulting in growth and development arrest in lettuce seedlings.