Identification and functional characterization of MdPIF3 in response to cold and drought stress in Malus domestica

PHYTOCHROME INTERACTING FACTORs (PIFs) are a subset of helix-loop-helix (bHLH) transcription factors, which play critical roles in plant growth and development, as well as in adaption to ambient environments. However, PIF members have not been completely identified in apple (Malus domestica), a widely distributed fruit crop with significant economical importance. Here, we characterized MdPIF3, the homolog of AtPIF3, and determined its role in response to abiotic stresses in apple. We first analyzed its gene and protein structure, and found that it contained bHLH domain, active phytochrome B binding (APB) motif, as well as active phytochrome A binding (APA) motif. Yeast-two-hybrid assays indicated that MdPIF3 formed a homodimer by itself and heterodimers with other MdPIFs. Moreover, MdPIF3 was responsive to light and cold treatment at both transcriptional and post-translational levels. Overexpression of MdPIF3 reduced cold tolerance but enhanced drought resistance in both apple callus and Arabidopsis. Key message The bHLH-type protein, MdPIF3, plays a key role in cold and drought tolerance in plants.

Automated summary

MdPIF3, a bHLH-type protein, plays a key role in cold and drought tolerance in plants.