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SiFBA5, a cold-responsive factor from Saussurea involucrate promotes cold resilience and biomass increase in transgenic tomato plants under cold stress


 Background

 Saussurea involucrate survives in extreme arctic conditions with strong cold resistant ability. The species occurs in rocky, mountainous habitats at elevations of approximately 2400-4100m with year-round snowfall and freezing temperatures providing a magnificent model and abundant gene pool for dissecting plant stress responses. Fructose-1,6-Bisphosphate Aldolase (FBA) mediates the reverse conversion of fructose 1,6-bisphosphate (FBP) into dihydroxyacetone phosphate (DHAP) and glycerol triphosphate (GAP) during glycolysis or gluconeogenesis, which is the key enzyme in this reaction. Saussurea involucrate can survive in extremely low temperature environment, which shows that it has extremely high photosynthesis efficiency. Significantly, the underlying mechanism of its cold tolerance is yet to be unveiled. Therefore, our work aims to explore potential molecular mechanisms.
Results

In this study, we identified a cold-responsive gene SiFBA5 that based on a preliminary low-temperature genome-wide transcriptional profiling in S. involucrata. Expression analysis showed that cold temperature rapidly induced transcriptional expression of SiFBA5, suggesting that SiFBA5 participates in initial stress responses. Subcellular localization showed that SiFBA5 is localized to the chloroplast. We then generated transgenic tomato plants overexpressing SiFBA5 derived by a CaMV 35S promoter. Phenotypic observation suggested that the transgenic overexpress plants displayed increased cold tolerance, photosynthesis efficiency, and carbohydrate accumulation in comparison with wild-type plants.
Conclusion

Collectively, our results demonstrated that SiFBA5 positively regulates plant response to cold stress, making it a promising candidate for improving cold tolerance in crops.