Inhibitory Mechanism Of Linalool On Botrytis Cinerea And Gray Mold Of Tomato

Tomato（Solanum lycopersicum L.）has high nutritional value.China is leading country in the total production of tomato in the world.Gray mold often occurs on tomato plants,not only in the growth period,but also in the post-harvest storage.It has been listed as the first tomato disease in some areas.Looking for green prevention and control methods of diseases has become the future research trend.This paper aims to study the prevention and control effect of linalool on tomato gray mold.Further explore the mechanism of action of linalool.It provides technical support and theoretical basis for the application of linalool in the green prevention and control of tomato gray mold.The main results are as follows:1.Linalool can inhibit the growth of Botrytis cinereaWhen the concentration of linalool is higher than 1 m L·L^-1,it has a significant inhibitory effect on the growth of Botrytis cinerea.The spore germination and spore vitality inhibition tests showed that 1 m L·L^-1of linalool could significantly inhibit the germination of Botrytis cinerea.The bacterial suspension was stained with propidium iodide（PI）and fluorescein diacetate（FDA）,and the fluorescence intensity showed that linalool could effectively inhibit spore viability.Subsequently,the membrane permeability and defense enzyme activity of Botrytis cinerea were determined.1 m L·L^-1linalool could effectively destroy the membrane structure of the mycelium.After treatment with linalool,the activities of superoxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）in the mycelia fluid were significantly reduced,and the content of malondialdehyde（MDA）was significantly increased,which showed that linalool was antioxidant to Botrytis cinerea mycelium.This indicates that the damage of linalool to the antioxidant capacity of Botrytis cinerea mycelium is an important cause of its membrane lipid damage.2.Linalool spray can alleviate the occurrence of tomato leaf gray moldSpraying 1 m L·L^-1linalool on tomato leaves inoculated with Botrytis cinerea significantly inhibited the growth of spots on tomato leaves and significantly reduced the diameter of the spots.The activities of antioxidant enzymes superoxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）were significantly increased,and the content of malondialdehyde（MDA）was significantly decreased.The results showed that linalool might alleviate the oxidative stress caused by Botrytis cinerea by inducing the activity of antioxidant enzymes in tomato leaves.In addition,after spraying 1 m L·L^-1linalool,the activities of phenylalanine ammonia-lyase（PAL）and polyphenol oxidase（PPO）,two key enzymes in phenylpropane metabolism pathway,were also significantly increased.They were beneficial to the accumulation of secondary metabolites and they reduced the damage of Botrytis cinerea to tomato leaves.Finally,the safety of linalool was tested.It was found that 1 m L·L^-1linalool had no inhibitory effect on the photosynthesis of tomato leaves.3.Linalool fumigation can alleviate the damage of gray mold to tomato fruitLinalool could significantly inhibit the growth of gray mold spot on the fruit,and the diameter of the spot was significantly reduced.The activities of antioxidant enzymes superoxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）were significantly increased,and the content of malondialdehyde（MDA）was significantly decreased.The results showed that linalool might alleviate the oxidative stress caused by Botrytis cinerea by inducing the activity of antioxidant enzymes in tomato fruit.In addition,after 30μL linalool fumigation,the activities of phenylalanine ammonia lyase（PAL）and polyphenol oxidase（PPO）,two key enzymes in phenylpropane metabolism pathway,were also significantly increased.The accumulation of total phenolic flavonoids and strong reducing agent reduced ascorbic acid（As A）,the secondary metabolite,reduced the damage of Botrytis cinerea to tomato fruit.Finally,the safety of linalool was tested,and linalool fumigation had no inhibitory effect on the accumulation of vitamin C and soluble solids in tomato fruit.