Effects Of Endophytic Bacteria In Desert Plants On Drought And Salt Resistance Of Plants

Endophytic bacteria are an important part of the micro-ecological system in plants.Some endophytic bacteria can effectively promote the growth of plants and improve the resistance of plants under stress.In this study,the endophytic bacteria in the leaves and roots of desert plants in arid areas were studied.The effects of different endophytic bacteria on plant growth and rhizosphere community structure under drought and salt stress were systematically studied.The main findings are as follows:1)Endophytic bacteria in desert plants have the potential to promote plant growth.The function of 65 endophytic bacteria in leaves and roots of various desert plants was determined by plate culture method.It was found that 86.9% of the strains had strong nitrogen fixation capacity,55% of the strains had phosphorus solubilizing ability,and 61.6% of the strains IAA can be produced,29.8% of the strains produce iron carriers,31.6% of the strains produce ACC deaminase,and 20.9% of the strains can grow at concentrations greater than 10% NaCl.It indicates that the endophytic bacteria of desert plants have rich functional diversity and strong salt tolerance,and can produce a variety of regulatory substances required for plant growth,which provides an important reference value for further study of the growth-promoting effects of strains on plants.2)Endophytic bacteria in desert plants can effectively increase the germination rate of plant seeds.The seed soaking study showed that compared with the control group,the seed germination rate of the seeds after soaking was significantly increased,and the promoting effect of Hbc-6 and Xbc-9 was the most obvious.3)The strains Hbc-6 and Xbc-9 can effectively increase the growth ability of Arabidopsis thaliana.The effects of endophytic bacteria on the growth of Arabidopsis thaliana under drought and salt stress were studied using a plate co-culture system.The results showed that under normal conditions,the lateral roots of Arabidopsisthaliana co-cultured with Hbc-6 and Xbc-9 increased 1.6 and 0.8 times,respectively;the fresh weight increased by 1.8 and 0.5 times;the main root diameter and root hair length increased significantly.Under the treatment of 10% PEG6000,the Arabidopsis inoculated with Hbc-6 increased the diameter of the main root by 1.4 times and the number of lateral roots by 2.2 times,which is important for improving the tolerance of plant to drought stress.At the salt concentration of 50 and 100mmol/L,the main root diameter of Arabidopsis thaliana increased by 75% compared with the control group,and the number of lateral roots and root hair were significantly increased,too.Indicating that Hbc-6 was promoted the development of the roots of Arabidopsis thaliana to increase the growth ability of plants under salt stress.4)Inoculation of Hbc-6 and Xbc-9 can significantly promote the growth of maize under normal water content and drought stress.It was found that the maize plants inoculated with Hbc-6 and Xbc-9 had better growth status than the control group and other plants-inoculated under drought stress.The sharpening of the stoma was severe and star-shaped,while the plants inoculated with the strains Hbc-6 and Xbc-9 were less sharp.At the same time,Hbc-6 and Xbc-9 can effectively reduce the malondialdehyde content and conductivity of the plant,and increase the soluble sugar content,chlorophyll content,glutathione content and antioxidant enzyme activity of the leaves.It indicated that Hbc-6 and Xbc-9 promoted the growth of maize under drought stress by regulating morphology and physiological metabolism,and improved the adaptability of plants.5)High-throughput sequencing of Miseq 16 s rRNA revealed that the abundance and diversity of soil bacteria increased after inoculation.Compared with the control group,the OTU increased significantly after inoculation,especially under drought stress.At the same time,Hbc-6 can promote the colonization of Saccharibacteria,and its ability to remove metabolic waste from the soil can also indirectly increase the adaptability of plants to adverse environments.It shows that increasing the abundance and diversity of rhizosphere soil in arid environment can better promote the growth of plants.6)Inoculation of Hbc-6 and Xbc-9 can significantly increase the growth ability of maize under salt stress.Hbc-6 and Xbc-9 can significantly increase the biomass of maize under salt stress,and Xbc-9 can significantly promote the development of maize roots.The stomatal pores showed similar results to the drought treatment undersalt stress.As the degree of stress increased,the stomatal density increased gradually,the conductance decreased,and both ends of the stomatum sharpened sharply.Inoculation with Hbc-6 and Xbc-9 can alleviate stomatal deformation,maintain the shape of subsidiary cells,increase stomatal conductance(gs),photosynthetic rate(Pn),transpiration rate(E),and significantly increase plant biomass.It indicated that Hbc-6and Xbc-9 could effectively promote the growth of maize under salt stress and improve the adaptability of maize to salt stress.The results of this study indicate that endophytic bacteria in desert plants have many functional properties to promote plant growth.Inoculation with Hbc-6 and Xbc-9 could increase the growth ability of Arabidopsis thaliana and maize under normal conditions,drought stress and salt stress.The results laid a foundation for further elucidation of the interaction between endophytic bacteria and different plants,and provided a new solution to improve the stress resistance and crop yield of crops in desert areas.