<scp>AIR12</scp> confers cold tolerance through regulation of the <scp>CBF</scp> cold response pathway and ascorbate homeostasis
Qi Wang, Haifan Shi, Risheng Huang, Rong Ye, Yurong Luo, Zhenfei Guo, Shaoyun Lu
Abstract
Abstract Auxin induced in root culture ( AIR12 ) is a single gene in Arabidopsis and codes for a mono‐heme cytochrome b, but it is unknown whether plant AIR1 2 is involved in abiotic stress responses. MfAIR12 was identified from Medicago falcata that is legume germplasm with great cold tolerance. Transcript levels of MfAIR12 and its homolog MtAIR12 from Medicago truncatula was induced under low temperature. Overexpression of MfAIR12 led to the accumulation of H 2 O 2 in apoplast and enhanced cold tolerance, which was blocked by H 2 O 2 scavengers, indicating that the increased cold tolerance was dependent upon the accumulated H 2 O 2 . In addition, declined cold tolerance was observed in Arabidopsis mutant air12 , which could be restored by expressing MfAIR12 . Compared to the wild type, higher levels of ascorbic acid and ascorbate redox state, as well as transcripts of the C repeat/dehydration responsive element‐binding factor (CBF) transcription factors and their downstream cold‐responsive genes, were observed in MfAIR12 transgenic lines, but lower levels of those in air12 mutant. It is suggested AIR12 confers cold tolerance as a result of the altered H 2 O 2 in the apoplast that is signaling in the regulation of CBF cold response pathway and ascorbate homeostasis.