The Relationship Between Heavy Metal Morphology,Enzyme Activity And Autophagy In Pteris Vittata With The Stress Of Sb,As And Cd

Autophagy is a process in which the toxic,senescent,and dead cytoplasmic components of eukaryotes are phagocytosed by double-membrane vesicles to form autophagosomes,which are then transported to organelle lysosomes(mammals)or vacuoles(yeast/plants)for degradation and recovery.Three potential pathways of autophagy and heavy metals’ toxic effects on plants:(1)the toxic mechanism of heavy metals mainly causes damage to plant cells through reactive oxygen species(ROS),and ROS stress in plants can stimulate autophagy.(2)most heavy metals are stored in vacuoles in plants,and the key stage of autophagy is also carried out in vacuoles.(3)excessive heavy metals in plants will lead to the inactivation of key enzymes,the destruction of proteins and the death of organelles,etc.,while autophagy will degrade the damaged proteins and organelles and make them recycled.Based on the above three potential ways that cell autophagy with heavy metal toxicity has certain relevance,the experiment using ammonium chloride As a cell autophagy inhibitor,explore the centipede grass under hydroponic conditions under ammonium chloride stress in the body of the As,Sb,Cd form(using two consecutive extraction experiments)change and antioxidant system,the change trend of enzyme activity.The experimental results showed that the occurrence forms of As and Sb in centipedes were significantly different from that in Cd.As in plants was mainly in the form of ethanol and hydrochloric acid,accounting for more than 70%;Sb in the form of residue,accounting for more than 50%;Cd in the form of hydrochloric acid,accounting for more than 90%;and the proportion of residue,only about 1%.However,inhibition of autophagy can promote the transformation of As hydrochloric acid,Sb residue and Cd ethanol in centipede.Since autophagy is responsible for the degradation of damaged substances in the cells,these three forms are the main toxic forms of the three heavy metals in centipede.Through autophagy,the damaged organelles and proteins are degraded and partially reused by heavy metal ion replacement,so as to change the form of heavy metals and reduce the toxic effect of heavy metals on centipede grass.This is one of the reasons why centipede grass is resistant to a variety of heavy metals.Enzyme activity in cell autophagy is restrained,blade change tendency obvious,four kinds of enzymes in the leaves under the As stress and Sb in the leaves under the stress of APX,CAT and SOD enzyme activity were increased after adding ammonium chloride,although cell autophagy role,but under the stress of the As,Sb,centipede grass antioxidant system was not so is restrained,the mechanism of reactive oxygen free radicals accumulation has a variety of resistance.However,under the stress of Cd,the four enzyme activities in the leaves all decreased after the addition of ammonium chloride,indicating that the resistance of c.centipede to As and Sb was stronger than that of Cd.