Isolation and Characterization of Endophytic Bacteria From the Poaceae Family: Assessing Their Impact on Drought Stress and Plant Growth in Wheat

Abstract

Limited water resources and the increasing impact of global warming highlight the importance of endophytic bacteria (EB) given their unique tolerance to drought stress. In this study, we isolated EB from cultivated and wild Poaceae family members grown in arid or challenging environments in Lake Van Basin. We aimed to reveal plant growth promoting (PGP) characters in EB and to determine their potential to promote plant growth and reduce the effect of different drought levels in two different wheat cultivars (Tir (tolerant) and Bezostaja-1). 410 EB were isolated from 135 plants belonging to 19 taxa at different periods. In vitro tests revealed that 73.1% of the isolates can synthesize indole acetic acid (IAA), 34.4% can fix nitrogen, 37% can synthesize 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCd), 37.6% can solubilize phosphorus, and 93.9% can synthesize siderophore. IAA production and phosphorous solubility were the most common characters, coexisting in 59% of EBs. ACCd production, phosphorus solubilization, and nitrogen fixation were the most common features with a triple association of 0.49%. Although isolates selected according to EB characters showed differing effects on coleoptile, root and shoot length, germination percentage, shoot and root weight, and relative water content (RWC) in the early development period (EDP) of Bezostaja-1 cultivar under drought stress, some isolates had negative effects. However, Pseudomonas asturiensis G58S1, Pantoea agglomerans G129K1-1, Chryseobacterium rhizosphaerae G129S2, Acinetobacter calcoaceticus G118K1T, and Stenotrophomonas sp. G109K2-K isolates selected according to PGP trials and EDP results showed improved plant biomass, chlorophyll content, membrane permeability, germination power, and RCW, and protective effects against drought.