In vitro plant tissue culture serves as a pivotal platform to evaluate heavy metal phytotoxicity and the mitigation mechanisms mediated by biotization, defined as a metabolic response of plant cells to microbial inoculants. There are some reports that this process has employed plant growth promoting bacteria to establish an artificial symbiosis between them and tissue culture of plants. In this study, the impact of cadmium (Cd: 0.1, 0.5, and 1.0 mM) and biotization with Staphylococcus pasteuri strain Fs3 and Kocuria rhizophila strain Fs7 on the growth and cellular morphometry of Fouquieria splendens calli was non-destructively evaluated. Utilizing computer-assisted digital morphometric analysis and image segmentation, baseline morphometric descriptors and relative growth rate parameters were quantified at 52 and 76 days of culture. Principal Component Analysis (PCA) revealed a strain and dose-dependent geometric reprogramming under heavy metal stress. Under moderate stress, the Fs3 + Cd 0.1 mM treatment exhibited a prominent morphometric hormesis response, achieving the maximum area growth percentage, driving also the highest area and perimeter relative growth rates. Conversely, severe exposure to Cd 1.0 mM induced net cellular collapse and negative growth rates related to this extreme toxicity, biotization with K. rhizophila strain Fs7 acted as a structural biological rescue system, reversing tissue damage by maintaining a positive growth percentage and promoting a strong three-dimensional spherical compaction, as evidenced by the highest distance dispersion index value. These findings demonstrate that endophytes plastically modulate callus geometry as an adaptive strategy for cell tolerance mechanisms under severe chemical stress.