Effect Of Isoprothiolane On Physiological Characteristics And Soil Microbial Community In Rhizosphere Of Isoetes Sinensis

Isoetes sinensis is an endangered vascular plant,because of the serious threat to the habitat,the number of wild population has decreased year by year,and it is almost extinct.Currently,Isoetes have been listed as national key protected plants in China.Isoprothiolane is one of the most commonly used pesticides in rice producing areas in China,it has not been reported how its use will affect Isoetes sinensis.Therefore this study used isoprothiolane,use of physiological indexes and soil enzyme routine determination method,Biolog-Eco microplate method and High-throughput sequencing to explore the physiological characteristics of Isoetes sinensis,rhizosphere soil enzyme activity,and soil microbial community structure and function under different concentrations,to reveal the mechanism of damage on the pesticide stress of Isoetes sinensis and provide information for further protection of Isoetes sinensis.The results shou that:(1)With the increase of isoprothiolane concentration and treatment time increase,both the photosynthetic system and the membrane system of Isoetes sinensis have been poisoned,while the activity of the protective enzyme system has increased,which has enhance the resistance to isoprothiolane of Isoetes sinensis.At the later stage,in addition to the MDA content and membrane relative conductivity,the physiological indexes were recovery trend.It shows that although isoprothiolane is toxic to Isoetes sinensis,this effect is relatively weak and can be restored.(2)With the increase of the concentration of isoprothiolane,the activity of soil dehydrogenase,catalase,urease,amylase,cellulase,invertase,acid phosphatase and acid phosphatase increased first and then decreased.This indicated that the low concentration of isoprothiolane had a stimulatory effect on the activity of these seven soil enzymes,and high concentration of isoprothiolane had an inhibitory effect on the activity of these seven soil enzymes.(3)Biolog-Eco microplate was used to study the differences in metabolic capacity and functional diversity of microbial community in the rhizosphere soil of Isoetes sinensis under different concentrations of isoprothiolane.Research shows that underlow concentration,isoprothiolane has a certain stimulatory effect on the microbial activity of the rhizosphere soil of Isoetes sinensis,but it has an inhibitory effect at high concentrations.The low concentration of isoprothiolane had a certain degree of promoting the use of six types of carbon sources by soil microorganisms,while high concentration of isoprothiolane had a certain degree of inhibition on the degree of utilization of these six types of carbon sources by soil microorganisms.Although isoprothiolane is effective in suppressing the utilization of most carbon sources,the availability of Tween 80,?-cyclodextrin,glucose-1-phosphate,D,L-?-glycerophosphate,D-glucuronide,2-hydroxybenzoic acid,L-arginine,L-phenylalanine and glycyl-L-glutamic acid has a promoting effect.(4)By high-throughput sequencing(HTS)technology to study the changes of Isoetes sinensis rhizosphere soil microbial community diversity under different concentrations of isoprothiolane,the research shows that isoprothiolane had little effect on the bacterial diversity in the rhizosphere soil of Isoetes sinensis and had a greater impact on the diversity of soil fungi.With different concentrations of isoprothiolane,there was a certain similarity between soil microorganisms at various concentrations,The soil bacteria structure of 10 mg·kg-1 and 50 mg·kg-1,30 mg·kg-1 and 40 mg·kg-1were similar,the structure of soil fungi of the control group and 20 mg·kg-1 was similar.Above all,isoprothiolane has certain toxic effects on Isoetes sinensis,but with the passage of time,this toxic effect is reduced;the enzyme activity of the rhizosphere soil of Isoetes sinensis will be affected to a certain extent,different enzymes have different sensitivity to isoprothiolane.For the first time,the Biolog-Eco microplate method and the high-throughput sequencing method were used to study the functional diversity and structural diversity of micro-organisms in the rhizosphere soil of the Isoetes sinensis,the results showed that the structure of soil microbes in the rhizosphere soil of Isoetes sinensis has changed,and the utilization of carbon sources has also changed.