SlWRKY2 orchestrates cold tolerance via phytochromes interaction and SlPIF4 stabilization in tomato

Here, we identify the transcription factor SlWRKY2 as a critical hub linking phytochrome-mediated light perception with cold stress adaptation in tomato (Solanum lycopersicum). Under cold stress, low red/far-red light ratios significantly induce SlWRKY2 expression and protein accumulation, with phytochrome B (SlphyB) repressing and SlphyA promoting this process.

Genetic analyses confirm that SlWRKY2 functions downstream of SlphyB and SlphyA, physically interacts with both SlphyB1 and SlphyA, and acts in a regulatory module where SlphyB negatively regulates cold tolerance while SlphyA exerts a positive effect. Moreover, both cold stress and light signals promote the formation of SlWRKY2 condensates consistent with liquid-liquid phase separation (LLPS). Functionally, SlWRKY2 directly interacts with and stabilizes the light-signaling regulator PHYTOCHROME-INTERACTING TRANSCRIPTION 4 (SlPIF4).