Effects of amino-oligosaccharides on induced disease resistance and biochemical indices of wolfberry
[Objective]Amino-oligosaccharide(AOS)is a kind of plant immune attractor,which can induce and activate plant immune system,promote growth and improve disease resistance.In this study,by spraying AOS on leaf surface,the incidence of wolfberry disease and physiological and biochemical indexes were observed and analyzed,and the effects of AOS on the growth of wolfberry plants and the physiological mechanism of inducing disease resistance were clarified.[Method]In this experiment,four-year-old wolfberry'Ningqi Ⅶ'plants were selected as experimental materials.Clean water was used as a control treatment while AOS solution was sprayed onto the foliage in the experimental group.Starting from the initial flowering period,5%AOS solution diluted 800 times was sprayed onto the leaf surface four times,once every 15 days.After 32 days of induction,the onset of barbary wolfberry leaf spot disease was investigated for a total of three times.At the same time,leaf samples were collected to determine leaf thickness,chlorophyll content,active oxygen metabolism pathway,phenylpropane metabolism pathway key enzyme activities and secondary metabolites content.[Result]The results showed that by spraying AOS on leaves for 32 days,the contents of chlorophyll,O2-(Superoxide anion)and H2 O2(Hydrogen peroxide)levels of wolfberry'Ningqi Ⅶ'reached the highest,which were increased by 63.04%,13.27%and 206.14%compared with control group,respectively.And antioxidant enzyme activity activities of SOD(superoxide dismutase),POD(peroxidase)and PAL(phenylalanine aminolyase)reached their peak values with notable increases compared to those in the control group.Specifically,there was a significant increase of 13.27%in O2-level,206.14%increase in H2 O2 level,19.56%increase in SOD activity,45.46%increase in POD activity,and 48.85%increase in PAL activity.The MDA content is reduced to a minimum,decreased by 37.43%compared with control group.After 39d of the induction,the incidence and disease index of'Ningqi Ⅶ'leaf spot were the lowest,which were 5.90%and 1.66,respectively,and the relative control effect was the best,reaching 83.02%.At this time,the activity of 4CL(4-coumaric acid coA ligase)activity was the highest,which was 107.39%higher than that of control group.Meanwhile,the contents of lignin,total phenol and flavonoid of secondary metabolites also reached the highest,which were increased by 26.89%,63.98%and 19.69%,respectively,compared with the control group.The activity of CAT(catalase)and C4H(cinnamic acid-4-hydroxylase)after 46 days of induction were highest,which were 380.02%and 45.34%higher than the control group.[Conclusion]Foliar spraying with AOS can increase chlorophyll content of wolfberry'Ningqi Ⅶ'leaves,induce ROS production,and it can increase the content of O2-and H2 O2 to a certain extent.It can also enhance the activities of SOD,POD,CAT,PAL,C4H,4CL,reduce MDA content,and accumulate secondary metabolites such as lignin,total phenols and flavonoids.Therefore,it can significantly reduce the natural incidence rate and disease index of leaf spot disease.The results can provide a theoretical basis for the application of amino-oligosaccharide in harmless cultivation of wolfberry.
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