Alleviation drought stress of Bromus species using mycorrhizal fungi contributed with drought-responsive biomarkers

Pasture degradation is a main problem in semiarid regions. Therefore, rehabilitation of pasture needs sustainable ways such as using soil beneficial microorganisms to ameliorate endemic plant development, especially under drought conditions. This experiment addresses the effect of inoculation arbuscular mycorrhizal fungi (AMF) ( Glomus intraradices and Glomus mosseae ) on resistance against water deficit including 40, 60 and 80% of soil humidity based on field capacity with two endemic Bromus species ( B. tometolus and B. kopetdaghensis ) for two years (2017–2018 and 2018–2019) with focusing on morphological traits and physiological drought-responsive biomarkers. The results showed that increasing water deficit reduced shoot dry weight, photosynthesis pigment content, and fluorescence significantly, which was correlated with a significant enhancement in proline accumulation and antioxidants enzyme activity. G. intraradices had more positive effects on shoot dry weight than G. mosseae. Both Bromus species under water deficit stress accumulated considerable proline. G. intraradices and G. mosseae resulted in more superoxide dismutase, peroxidase, catalase and ascorbate peroxidase activities in both species; however, G. intraradices showed more proline content and enzyme activity than G. mosseae . The compensatory effect of AMF in alleviating the negative effect of reduced soil humidity was due to an increase in proline accumulation and activation of some antioxidant enzymes as biomarkers which improved water deficit tolerance of Bromus.