Expression of the LlBANMT Gene from Sea Lavender Leads to the Accumulation of β-alanine Betaine and Enhanced Stress Resilience in Transgenic Tobacco Plants

The increasing demand for stress-resilient crop varieties necessitates the exploration of new techniques aimed at enhancing plant tolerance to abiotic stress. Betaines play a significant role in plant adaptation, and the use of glycine betaine can increase the survival, tolerance, and productivity of crops. Within the Plumbaginaceae family, β‑alanine betaine (βAB) biosynthesis occurs through a 3-step methylation process catalyzed by β‑alanine N‑methyltransferase (BANMT). Despite its biochemical advantages, this pathway remained unexplored as a strategy for enhancing plant stress resistance. In this study, the Limonium latifolium methyltransferase gene (LlBANMT) was heterologously expressed in Escherichia coli and Nicotiana tabacum for the first time, resulting in the accumulation of βAB and improved tolerance to a variety of abiotic stresses for both bacteria and plants. Moreover, in the transgenic tobacco, there was a noticeable reduction in oxidative stress, evidenced by lower levels of malondialdehyde and hydrogen peroxide, coupled with an increase in peroxidase activity and the total antioxidant capacity of the extracts. The transcriptional levels of corresponding stress-responsive genes were also altered in transgenic tobacco. The accumulation of βAB was also linked to reduced seed germination latency, faster roots elongation, and enhanced growth biometrics. The present findings suggest that incorporating βAB biosynthesis through genetic engineering could be a promising strategy for enhancing crop resilience to various abiotic stresses, thereby contributing to global food security amidst changing environmental conditions.