Studies On The Defense Enzymes Of Strawberry Against Mycosphaerella Fragariae

This article take strawberry's leaf spot as the object of studing,the biological characteristics of Mycosphaerella fragariae(Tul) lindaut and the activities' determinations of defensive enzymes in leaves of different varieties of strawberry after infecting Mycosphaerella fragariae has been studies.The experimental results were summarized as follows:1.The biological characteristics of Mycosphaerella fragariae.Researched the biological characteristics of Mycosphaerella fragariae from nutritional conditions and physical conditions.Nutritional conditions including nitrogen source(Asparagine,KNO₃,NH₄NO₃,Peptone) and carbon sources(Malt Sugar,Sucrose, Glucose,Mannitol).Compared with degree of utilization of disease germ to different nitrogen sources and carbon sources,analyze which kind of nitrogen sources and the carbon sources are more advantageous to disease germ's growth.The results demonstrate that using the Glucose as carbon source,using the Asparagine,KNO₃,NH₄NO₃ and Peptone as nutritional source respectively.There is much difference in colony's characteristics and is less difference in colony's size when the disease germ grows on medium of different nitrogen element.Obviously,the influence of nitrogen source to colony's characteristics is more than growth speed of mycelium.The Peptone is the most advantageous nitrogen element to mycelium.Using the Asparagine as nitrogen source,using the Malt Sugar,Sucrose,Glucose,Mannitol as carbon source respectively.The results demonstrate that the Malt Sugar is the most advantageous carbon element to mycelium.The research of physical conditions demonstrate that the pH's scope which is the most suitable to disease germ is 6.0-7.0,and the temperature's scope is 25℃-30℃.2.Studies on the defense enzymes of strawberry resist Mycosphaerella fragariae:This part of experiment selects 6 kinds of different resistant strawberry cultivars,determining the contents of defensive enzymes of strawberry's leaves which are infected by Mycosphaerella fragariae and analyzing the changes of enzymes activity of PPO,PAL,CAT,SOD,POD after infection.Totally,the results demonstrate that all the cultivars of strawberry's enzymes activity were higher than the comparison.The changed characteristic of the enzymes activity of resistant eultivars was the activity point emerged earlier,and some one emerged two higher points. The changed characteristic of the enzymes activity of mid-susceptible and susceptible cultivars was the activity point emerged later,and the point close to comparison's.,and the activity changed gently.These performances showed that PPO,PAL,CAT,SOD and POD had played certain roles at strawberry resists Mycosphaerella fragariae.All of these above can be as the physiological index in resistance identification.