Endophytic Fungi Regulate HbNHX1 Expression and Ion Balance in Hordeum bogdanii under Alkaline Stress

Plants cope with abiotic stress in several ways, including by collaborating with microorganisms. an endophytic fungus, has been shown to improve plant tolerance to extreme external environments. is a known salt-tolerant plant with the potential to improve alkaline lands. plays a key role in the transport of ions in the cell and is overexpressed in plants with increased salt tolerance. However, the expression levels of in endophytic fungal symbionts in have not been elucidated. We used (E+) with the endophytic fungi and (E-) without the endophytic fungi and compared the differences in the ion content and expression between the shoots and roots of E+ and E- plants under alkaline stress. The absorption capacity of both K and Na of with endophytic fungi was higher than that without endophytic fungi. In the absence of alkaline stress, endophytic fungi significantly reduced the Cl content in the host . Alkaline stress reduced SO content in ; however, compared with E-, endophytic fungi increased the content of SO in E+ plants. With an increase in the alkaline concentration, the expression of in the roots of with endophytic fungus exhibited an upward trend, whereas the expression in the shoots exhibited a downward trend first and then an upward trend. Under 100 mmol·L mixed alkaline stress, the expression of in E+ was significantly higher than that in E-, indicating that endophytic fungi could increase the Na region in vacuoles. The external environment affects the regulation of endophytic fungi in and that endophytic fungi can play a key role in soil salinization. Therefore, the findings of this study will provide technical support and a theoretical basis for better utilization of endophytic fungi from in saline land improvement.