Dark septate endophyte decreases stress on rice plants

Abstract

Abiotic stress is one of the major limiting factors for plant development and productivity, which makes it important to identify microorganisms capable of increasing plant tolerance to stress. Dark septate endophytes can be symbionts of plants. In the present study, we evaluated the ability of dark septate endophytes isolates to reduce the effects of water stress in the rice varieties Nipponbare and Piauí. The experiments were performed under gnotobiotic conditions, and the water stress was induced with PEG. Four dark septate endophytes were isolated from the roots of wild rice (Oryza glumaepatula) collected from the Brazilian Amazon. Plant height as well as shoot and root fresh and dry matter were measured. Leaf protein concentrations and antioxidant enzyme activity were also estimated. The dark septate endophytes were grown in vitro in Petri dishes containing culture medium; they exhibited different levels of tolerance to salinity and water stress. The two rice varieties tested responded differently to inoculation with dark septate endophytes. Endophytes promoted rice plant growth both in the presence and in the absence of a water deficit. Decreased oxidative stress in plants in response to inoculation was observed in nearly all inoculated treatments, as indicated by the decrease in antioxidant enzyme activity. Dark septate endophytes fungi were shown to increase the tolerance of rice plants to stress caused by water deficiency.

Dark Septate Endophyte Improves Drought Tolerance of Ormosia hosiei Hemsley & E. H. Wilson by Modulating Root Morphology, Ultrastructure, and the Ratio of Root Hormones

“…Previous studies have suggested that the network of DSE hyphae that connect the root cells of the plant with the rhizosphere could help plants to maintain water content and transport nutrients to the plant under drought stress conditions [29]. In addition, DSEs could also increase proline content and antioxidant enzyme activity in host plants [30]. Proline and antioxidant enzymes play active roles in maintaining the osmotic pressure of cells and enhancing the ability of scavenging reactive oxygen species.…”

Dark septate endophytes colonizing the roots of ‘non-mycorrhizal’ plants in a mine tailing pond and in a relatively undisturbed environment, Southwest China

“…Direct evidence using isotope labeling revealed that a dematiaceous hyphomycete DSE, Heteroconium chaetospira formed a mutualistic symbiosis with Brassica campestris, a non-mycorrhizal plant of the Cruciferae family, in which the fungus supplied host plants with essential mineral nutrients (mainly N), in exchange for photosynthetically fixed carbohydrates (Usuki & Narisawa 2007). Subsequently, more experimental data have provided new insights to understand further aspects of DSE functioning, for example, releasing of phosphorus (P) from soil insoluble phosphates, for example, calcium phosphate to crops (Spagnoletti et al 2017), producing auxin volatile organic compounds to stimulate plant growth (Berthelot et al 2016), increasing the plant tolerance against water deficit (Santos et al 2016), and against fungal disease (Yuan et al 2016). Moreover, differently from AM fungi, having a broad host spectrum and the axenic cultivability on economically viable synthetic media, make DSEs suitable for mass scale inoculum production for application in reforestation of mine spoils.…”

Plant-mycorrhizal fungi interaction and response to inoculation with different growth-promoting fungi

“…However, studies indicate that growth promotion may occur indirectly or directly. The first way would be through plant protection from abiotic stresses, such as drought (Santos et al, 2017;Zhang et al, 2017), salinity (Qin et al, 2017) and high concentrations of heavy metals (Wei et al, 2016), as well as through the production of phytohormones or similar substances (Berthelot et al, 2016). The second would be through the facilitation of nutrient absorption, mainly from organic sources (Usuki & Narisawa, 2007;Vergara et al, 2018b).…”