Physiological And Molecular Mechanisms Of La On Seed Germination And Early Root Development Of Arabidopsis Thaliana

Lanthanum(La)has been a plant growth regulator in agriculture for nearly 50 years.Low concentration of lanthanum promotes the growth of crops,but high concentration has a toxic effect on plants.Although we have made many progress in the physiological mechanism research of lanthanum regulating plant growth and development in recent years,the mechanism of La on root development and early seedling growth is still unclear.Based on Arabidopsis thaliana,we studied the mechanism of lanthanum regulating root development and early seedling growth by using plant physiology,pharmacology,molecular biology and genetics.The main results of the paper are as follows:1.High concentration of La inhibited the growth of the main root(PR)and induced the occurrence of lateral root(LR).La induced cell death in PR root tip,resulting in the loss of mitotic potential and stem cell activity of meristem cells.La also affected the expression of auxin transporter,thereby affecting the distribution of IAA in root tip.2.La induced the overaccumulation of reactive oxygen species(ROS)in PR.Reducing the accumulation of ROS on the root tip and alleviating the inhibitory effect of La on the growth of PR,thereby enhancing the mitotic potential of the meristem cells,increasing the accumulation of auxin in the root tips,and improving the survival rate of the root tip cells.3.La induced endocytosis,and we found that ROS was involved in the endocytosis process induced by La.These studies indicate that La affects root growth,at least in part,by regulating the ROS level of roots to induce PR cell death and subsequent auxin redistribution,resulting in rearrangement of root system.4.The low concentration of La had no significant effect on the seed germination of Arabidopsis,and the high concentration of La had a significant inhibitory effect on seed germination.The inhibition and recovery experiment showed that the inhibitory effect of La on seed germination could not be eliminated.Taken together,La induced ROS overaccumulation in roots.High concentration of La inhibited the grovwth of PR and induced the occurrence of LR.In addition,La also induces endocytosis.High concentration of La had a significant inhibitory effect on seed germination,and the inhibitory effect on seed germination could not be eliminated after the recovery culture.