Studies On The Pathogenic Mechanism Of Botrytis Cinerea Toxin And Its Inactivation

The tomato grey mold, which is caused by Botrytis cinerea, is one of the seriously damaged plant diseases in the world. Toxin, a kind of secondary metabolites of plant pathogens, is closely related to many plant diseases. Botrytis cinerea toxin's biological activity and phathogenesis, the screening and mechanism of the passivating substance of the toxin, had been separately studied in this paper.This study provides a new way to control Botrytis cinerea,and has important theoretical and practical significance.The biological activitis of the crude toxin of the Botrytis cinerea were detected through dipping detached leaves and seedlings, and the results showed that the toxin could make tomato seedlings wilt, detached leaves get diseased, and the symptoms become more obvious with the toxin concentration increased and treatment time prolonged.Toxin's pathogenic mechanism was studied in three aspects:the influence of Botrytis cinerea crude toxin on chloroplasts, membrane permeability and four kinds of defence enzymes of tomato leaves. The results showed that the toxin damaged chloroplasts of tomato leaves and the severity of damage became more and more serious as treatment time prolonged, the toxin caused MDA content of tomato leaves to increase and MDA content was proportional to the concentration of the toxin, the activity of four defence enzymes (CAT,POD,SOD,PPO) of tomato leaves were decreased when they exposed to the toxin. As a result, tomato leaves caught the desease.KMnO4, Na2CO3, C6HgO7, H3BO3 and K3C6H5O7 had strong passivating influence on Botrytis cinerea crude toxin, were screened from twenty one compounds for trial by studying the pinprick of detached leaves, mycelial growth inhibition, conidial germination inhibition. KMnO4, Na2CO3, C6H8O7, Na2SiO3 and Na2HPO4 obviously inhibited conidial germination. Botrytis cinerea mycelial growth had been strongly inhibited by KMnO4 Na2CO3 and C2H2O4.The passivation system of Botrytis cinerea toxin impacted dynamically on the four defence enzymes of tomato leaves. Botrytis cinerea crude toxin was treated with the concentration of 0.5gL-1Na2CO3, 1.5gL-1 Na2CO3,3gL-1Na2CO3 and 5gL-1Na2CO3 respectively. The dynamic variation of the four defence enzymes of tomato leaves were observed after being dealt with the above four passivation system of Botrytis cinerea toxin. The result showed that the concentration of 1.5gL-1Na2CO3 and 3gL-1Na2CO3 had strong passivation effect on the crude toxin.The both above passivation systems Botrytis cinerea toxin could increased the activities of the four defence enzymes of tomato leaves compared with Botrytis cinerea toxin.The passivation system of the Botrytis cinerea toxin impacted the ultrastructure of tomato leaf cells. The feature of tomato leaf tissues treated with sterile water as following: the organelles and lamellar structure were in order; most of the chloroplasts were fusiform, the bilayer was homogeneous, the mitochondrial cristae were clear;the matrix was uniform and fine; the nuclear membrane was integral. After being treated with toxin, the plasmolysis phenomenon appeared in the cells, the cell walls were seriously damaged; the chloroplast grana lamellae were fuzzy and in disorder and most of them disintegrated; chloroplast membrane and mitochondrial membrane were seriously damaged; mitochondrial cristae vanished, so vacuolization phenomenon took place. After being treated with toxin and 1.5 gL"1 Na2CO3, the cell walls fold slightly and the chloroplasts were out of shape a little; their bilayers were homogeneous and integral and the grana lamellae decreased but in order as well as trim; part of mitochondrial cristae disappeared but no vacuolization phenomenon took place. The results showed that 1.5 gL"1 Na2CO3 had strong passivation influence on the toxin and reduced the destruction of the ultrastructure of the tomato leaf organelles coming from the toxin.The passivation system of the Botrytis cinerea toxin impacted Genomic DNA molecules of tomato leaf. The results showed that the passivation system of the toxin could slow down the damage of the crude toxin on Genomic DNA of tomato leaf to some degree.