Trehalose accumulation in rice plants confers high tolerance levels to different abiotic stresses. This study reports the regulated overexpression of Escherichia coli trehalose biosynthetic genes (otsA and otsB) as a fusion gene to manipulate abiotic stress tolerance in rice. The fusion gene allows for a single transformation event and higher net catalytic efficiency for trehalose formation. The transgene was expressed under tissue-specific or stress-dependent promoters. Transgenic rice lines showed sustained growth, less photo-oxidative damage, and better mineral balance under salt, drought, and low-temperature stress. Trehalose levels in transgenic rice were 3–10 times higher than nontransgenic controls. The study suggests that trehalose's primary effect is not as a compatible solute but rather as a regulator of sugar sensing and carbohydrate metabolism. These findings demonstrate the feasibility of engineering rice for increased abiotic stress tolerance and productivity. The research highlights the potential of using transgenic approaches to improve abiotic stress tolerance in crops, as traditional breeding has had limited success. The study also shows that transgenic rice plants are salt-tolerant and maintain balanced mineral nutrition, with improved photosystem II function and increased photosynthetic capacity under nonstress conditions. The results indicate that trehalose may play a key role in modulating photosynthesis and stress tolerance in rice. The study concludes that overexpression of trehalose biosynthetic genes in rice has significant potential for improving abiotic stress tolerance and productivity. The findings suggest that similar approaches could be applied to other cereal crops like maize and wheat to enhance their tolerance to abiotic stresses.Trehalose accumulation in rice plants confers high tolerance levels to different abiotic stresses. This study reports the regulated overexpression of Escherichia coli trehalose biosynthetic genes (otsA and otsB) as a fusion gene to manipulate abiotic stress tolerance in rice. The fusion gene allows for a single transformation event and higher net catalytic efficiency for trehalose formation. The transgene was expressed under tissue-specific or stress-dependent promoters. Transgenic rice lines showed sustained growth, less photo-oxidative damage, and better mineral balance under salt, drought, and low-temperature stress. Trehalose levels in transgenic rice were 3–10 times higher than nontransgenic controls. The study suggests that trehalose's primary effect is not as a compatible solute but rather as a regulator of sugar sensing and carbohydrate metabolism. These findings demonstrate the feasibility of engineering rice for increased abiotic stress tolerance and productivity. The research highlights the potential of using transgenic approaches to improve abiotic stress tolerance in crops, as traditional breeding has had limited success. The study also shows that transgenic rice plants are salt-tolerant and maintain balanced mineral nutrition, with improved photosystem II function and increased photosynthetic capacity under nonstress conditions. The results indicate that trehalose may play a key role in modulating photosynthesis and stress tolerance in rice. The study concludes that overexpression of trehalose biosynthetic genes in rice has significant potential for improving abiotic stress tolerance and productivity. The findings suggest that similar approaches could be applied to other cereal crops like maize and wheat to enhance their tolerance to abiotic stresses.