Effects Of Endophytic Actinomycetes OsiSh-2 On The Growth Of Three Plant Seedlings

Plant endophytes are a kind of microorganisms with low toxicity,low pollution to the environment,and stable colonization.They live in the cells or intercellular spaces of healthy plants,but do not cause obvious damage to plants.Endophytes have diversity,including species diversity and distribution diversity.The diversity of species can be divided into endophytic bacteria,endophytic fungi and endophytic actinomycetes.Plant endophytes are an important type of microbial resources and an indispensable part of the plant microbial system.The endophytes that colonize plants can secrete ACC deaminase,indole acetic acid,siderophores and many other biological activities.Substances promote plant growth and improve plant disease resistance.In addition,it can also inhibit the growth of pathogens by competing with pathogens for space and nutrients.The secondary metabolites such as alkaloids,plant hormones,and antibiotics can directly kill pathogens.This study aimed at the early endophytic actinomycetes OsiSh-2,which was screened by our laboratory to promote the growth of rice,by irrigating the roots of Arabidopsis,tobacco and alfalfa with spore solution to observe the endophytic actinomycetes OsiSh-2 Effects on root length,plant height,plant dry and fresh weight,maximum leaf area and chlorophyll content of Arabidopsis,tobacco and alfalfa,determine whether it has the effect of promoting the growth and development of the three model plants,for future plant growth The further development of accelerators provides a theoretical basis.The main research contents and results are as follows:(1)Use the spore solution of rice endophytic actinomycetes OsiSh-2 with concentrations of 10~5 CFU/m L,10~6 CFU/m L,10~7 CFU/m L and 10~8 CFU/m L to irrigate Arabidopsis thaliana roots.In comparison,it was found that 10~5 CFU/m L spore solution can significantly increase the root length,fresh weight of the above-ground part and underground part of Arabidopsis;the 10~6 CFU/m L spore solution treatment group compared with the control group,the underground part of the dry weight was significantly increased by 90%,and the root length and the dry and fresh weight of the above-ground part were not significantly different;the fresh weight and dry weight of the above-ground part of the 10~7 CFU/m L spore solution treatment group were reduced compared with the control group;10~8 CFU/m L The fresh weight and dry weight of the above-ground part of the spore solution treatment group were significantly lower than that of the control group.Compared with the control group,the spore liquid treatment group of 10~7 CFU/m L and the spore liquid treatment group of 10~8 CFU/m L had no significant difference in their underground parts.The above results indicate that the OsiSh-2 spore solution with a concentration of 10~5 CFU/m L can promote the growth of Arabidopsis.When the concentration of the spore solution is higher than 10~6 CFU/m L,the growth and development of Arabidopsis begins to be inhibited.With the increase of the concentration of the spore solution,this growth inhibition becomes more obvious.(2)Compared with the control group,10~7 CFU/m L spore solution treatment group,and 10~8 CFU/m L spore solution treatment group,the root length of tobacco treated with 10~6 CFU/m L OsiSh-2 spore solution was Stem thickness,maximum leaf area,and plant chlorophyll content were all increased.The chlorophyll content was significantly increased by 18.4%compared to the control group,10~7 CFU/m L spore solution treatment group,and 10~8 CFU/m L spore solution treatment group is by54.1%and 106%.When the concentration of the spore solution reached 10~8 CFU/m L,the tobacco plant height,root length,stem thickness and other indicators decreased,and the growth of the tobacco itself was slightly inhibited,which showed that when the endophytic actinomycetes OsiSh-2 When the concentration of spore solution is10~6 CFU/m L,it can promote the growth of tobacco,but as the concentration of spore solution increases,the growth of tobacco is gradually inhibited.(3)Compared with the control group and 10~8 CFU/m L spore liquid treatment group,the alfalfa treated with 10~7 CFU/m L OsiSh-2 spore liquid irrigated its roots,and its plant height,root length,dry and fresh above ground and underground The weight has been improved,especially the root length,which increased significantly by 44.7%and 23.6%respectively.This indicates that 10~7 CFU/m L OsiSh-2 spore solution can promote the growth of alfalfa.With the gradual increase in the concentration of the endophytic actinomycete OsiSh-2 spore solution,this growth-promoting situation gradually weakened.When the OsiSh-2 spore solution concentration reached 10~8 CFU/m L,its plant height and root length were compared with 107 CFU The spore solution treatment group significantly reduced by 27.6%and23.6%,indicating that 10~8 CFU/m L OsiSh-2 spore solution could slightly inhibit the growth of alfalfa itself,but the roots of alfalfa treated at this concentration It is more developed than the control group.In addition,the chlorophyll content of alfalfa increases as the concentration of the spore solution increases.In summary,this study found that when the spore concentration of endophytic actinomycete OsiSh-2 is 10~5 CFU/m L,10~6 CFU/m L,and 10~7 CFU/m L,it may produce ACC deaminase and indole acetic acid.Other substances promote the growth of Arabidopsis,tobacco and alfalfa.This conclusion provides a theoretical basis for the further development of plant growth promoters in the future.