两种深色有隔内生真菌对天山雪莲幼苗生长的影响OA

Dark septate endophytes(DSE)are widely distributed in the roots of wild Saussurea involucrata and play important ecological roles.In this study,two fungal strains,SI-5 and SI-16,were identified using morphological and molecular methods.Their temperature adaptability and ability to produce soil enzymes and plant hormones were evaluated.In addition,the effects of the two symbionts on the growth and physiological characteristics of S.involucrata seedlings,as well as soil enzyme activities and plant hormone content in the growth substrate,were evaluated in comparison with those of non-inoculated plants.SI-5 and SI-16 were identified as Juxtiphoma sp.and Leptodophora sp.,respectively.It was found that both DSE strains successfully colonized seedling roots and significantly enhanced the activities of five soil enzymes as well as the content of auxin and cytokinin in the substrate.Compared with cultivation at constant temperature of 20℃,proline content in the SI-5 and SI-16 symbiotic groups increased by 74.5-107.9-fold under 20℃/10℃conditions,markedly lower than the 331.6-fold increase observed in the non-inoculated group,demonstrating stronger adaptation of symbiotic seedlings to cope with temperature changes.After 12 h of exposure under 0℃condition,peroxidase(POD)activity in the SI-5 symbiotic group increased significantly by 40.7%as compared with that of the pre-stress level,while superoxide dismutase(SOD)activity showed no significant change.In contrast,the non-inoculated group showed only a 7.8%increase in POD activity,accompanied by a significant decrease in SOD activity.The activities of five soil enzymes in the symbiotic groups were significantly higher than those in the non-inoculated group,and total auxin content increased by approximately 10%.The results provide insight into the mechanisms by which DSE enhance the ecological adaptability of S.involucrata.