*5.1.2 Dark septate endophytes and crop plants*

Dark Septate Endophytes (DSEs) are another important group of soil microorganism that have the capacity to associate with the roots of several plant species [96]. They sometimes colonize roots containing AMF [96]. The increasing severity of environmental conditions increase the importance of DSE. The associations of plants with DSE in high-stress environment is more frequent than their associations with AMF [97]. AMF and DSE have appeared to have similar and complimentary roles in various terrestrial ecosystem [98]. Grunig *et al*. [99] said that since DSEs can alter the performance of colonized plants, they can also play a vital role in determining the composition of plant communities. In the study of Barrow and Osuna [100], some plants colonized by DSE were more advantageous in the absorption of phosphorus from the soil and production of biomass when compared to those not inoculated. Though DSE is advantageous to plants, its colonization of roots can be of disadvantage to plants, such as decreases in the production of biomass [99]. Thus, the interaction of DSEs with plants seems to vary from mutualism to parasitism and may alter the competitive relations between plants [99].
