## 4 Discussion  
The present study documented a significant decrease in all growth attributes [47] alongside reduced leaf photosynthetic pigments. Similar decreases in plant growth and photosynthetic pigments due to drought have been previously reported in various crops, including soybean [48], maize [49], and cucumber [50]. Drought stress also significantly influences the leaf total phenolic content, although the increase or decrease varies among plant species and cultivars [51].  
Various adaptations are being explored to mitigate the harmful effects of abiotic stress with the prioritization of environmental sustainability in plant science. The utilization of bio-inoculants, particularly soil microbes, is advocated as a superior alternative to fertilizers and pesticides. Plant-growth-promoting rhizobacteria (PGPRs) are a vital soil component among these. Under diverse abiotic stresses, PGPRs have demonstrated efficacy in enhancing growth and nutrient uptake [52; 53; 54]. The priming agent MR-15 notably enhanced shoot length and shoot fresh and dry weights under stress conditions. Moreover, this PGPR strain increased the shoot length and induced resistance to drought stress.  
Figure 9: Effect of MR-15 inoculation on various attributes of yield ((**A**) number of fillers per plant, (**B**) spike length, (**C**) number of spikes per plant, (**D**) 100-grain mass, (**E**) total grains per plant, (**F**) total yield) in two wheat varieties grown with or without drought stress (non-primed (NP), hydro-primed (HP), Sehar-06 (V1), GA-2002 (V2), 100% field capacity (Control), 60% field capacity (Stress)). Different letters (a–d) denote a statistically significant difference.  
Similar findings have been reported in prior studies involving _Ocimum basilicum_ L. [55], maize [56], canola plants [57], and cotton [58] under various abiotic stresses, including drought, oxidative, and salt stresses.  
The application of different PGPR strains has been linked to increased root and shoot growth in various plants under drought stress, such as _Helianthus annuus_, potato, and cucumber, as documented by several researchers [59; 60; 61]. It is suggested that plant-growth-promoting rhizobacteria inherently enhance rhizospheric colonization, significantly increasing the crop yield [62].  
Our genome sequence analysis of this PGPR strain revealed a direct relation to Pseudomonas. Previous studies have also shown a correlation between root development and indole-3-acetic acid (IAA) secretion by PGPRs. IAA promotes root surface area, growth, development, and metabolism [63]. Hence, the observed increase in root development in both wheat varieties might be attributed to IAA secretion by the studied PGPR. MR-15 exhibited the highest concentration of IAA, supporting a positive relationship between IAA and root growth, as noted in other studies [64].  
Oxidative stress intensity correlates with the cellular Malondialdehydedehyde (MDA) concentration [65]. Elevated MDA levels trigger physiological disturbances within cells, including increased membrane permeability, reduced chlorophyll content, the degradation of macromolecules like proteins and nucleic acids, nutrient remobilization, and stunted crop growth [66; 67]. During drought stress, non-treated plants exhibited increased MDA and reactive oxygen species (ROS) contents (Figure 7), indicating the reduced antioxidant capacity of wheat plants. Conversely, wheat plants primed with the MR-15 strain displayed lower MDA and H2O2 contents than non-primed plants, highlighting an enhanced ability to scavenge oxidants under drought stress.  
Plant enzymes like SOD, POD, and CAT play pivotal roles in removing the reactive oxygen species generated during metabolism, maintaining a balance between their production and removal, and preventing oxidative damage [65].