Dark Septate Endophytes and Their Role in Enhancing Plant Resistance to Abiotic and Biotic Stresses

Abstract

In recent years, dark septate root endophytes (DSE) emerge as one of the poten- tial microbial groups in enhancing plant health and resistance to environmental stresses. In this chapter, we describe the diversity of DSE, host specificity, and their role in nutrient uptake by the plant. The mechanism of plant stress tolerance to environmental stresses and possible application of DSE isolates in agricultural practices are also elucidated. Estimation of DSE diversity is difficult due to their sporulating and non-sporulating life forms of which generates problems in the DSE identification. In addition, majority members of DSE fungi showed no host specificity with their associated plant. During plant-DSE association, hyphae have shown to be important in nutrient transfer from the DSE to their host plant. Nutrients obtained by the hyphae from the soil will be translocated inter- and intracellularly into plant cells through various mechanisms. In extreme environ- mental condition, such as high Cd (cadmium), DSE affects plant physiology by regulating GSH (glutathione) metabolism and thiol compound contents in the host plant to alleviate Cd toxicity. Due to their potential for increasing crop pro- ductivity and resistance to abiotic and biotic stresses, the studies now focus on developing a simple and low-cost standardized formulation that is applicable to agricultural practices. It is supported by the fact that members of DSE are easily cultured and propagated in the laboratory. Current effective application of DSE involves the development of superior plant seedling through inoculation of the DSE isolates during plant propagation by tissue culture or seeds.