Enhancement of plant cold tolerance by soybean RCC1 family gene GmTCF1a.

Background: Low temperature severely limits the growth, yield, and geographic distributions of soybean. Soybean plants respond to cold stress by reprogramming the expression of a series of cold-responsive genes. However, the intrinsic mechanism underlying cold-stress tolerance in soybean remains unclear. A. thaliana tolerant to chilling and freezing 1 (AtTCF1) is a regulator of chromosome condensation 1 (RCC1) family protein and regulates freezing tolerance through an independent C-repeat binding transcription factor (CBF) signaling pathway.

Results: In this study, we identified a homologous gene of AtTCF1 in soybean (named GmTCF1a), which mediates plant tolerance to low temperature. Like AtTCF1, GmTCF1a contains five RCC1 domains and is located in the nucleus. GmTCF1a is strongly and specifically induced by cold stress. Interestingly, ectopic overexpression of GmTCF1a in Arabidopsis greatly increased plant survival rate and decreased electrolyte leakage under freezing stress. A cold-responsive gene, COR15a, was highly induced in the GmTCF1a-overexpressing transgenic lines.

Conclusions: GmTCF1a responded specifically to cold stress, and ectopic expression of GmTCF1a enhanced cold tolerance and upregulated COR15a levels. These results indicate that GmTCF1a positively regulates cold tolerance in soybean and may provide novel insights into genetic improvement of cold tolerance in crops.