BYPASS1-LIKE, A DUF793 Family Protein, Participates in Freezing Tolerance via the CBF Pathway in Arabidopsis

Abstract

The C-REPEAT BINDING FACTOR signaling pathway is strictly modulated by numerous factors and is essential in the cold response of plants. Here, we show that the DUF793 family gene <i>BYPASS1-LIKE</i> modulates freezing tolerance through the CBFs in <i>Arabidopsis</i>. The expression of <i>B1L</i> was rapidly induced under cold treatment. Comparing to wild type, <i>B1L</i> knockout mutants were more sensitive to freezing treatment, whereas B1L-overexpressing lines were more tolerant. The expression of <i>CBF</i>s and CBF target genes was significantly decreased in <i>b1l</i> mutant. Using yeast two-hybrid screening system, 14-3-3λ was identified as one of proteins interacting with B1L. The interaction was confirmed with bimolecular fluorescence complementation assay and co-immunoprecipitation assay. Biochemical assays revealed that <i>b1l</i> mutation promoted the degradation of CBF3 compared to wild type, whereas <i>14-3-3κλ</i> mutant and <i>b1l 14-3-3κλ</i> mutant suppressed the degradation of CBF3. Consistently, <i>14-3-3κλ</i> and <i>b1l 14-3-3κλ</i> mutants showed enhanced freezing tolerance compared to wild type. These results indicate that B1L enhances the freezing tolerance of plants, at least partly through stabilizing CBF. Our findings improve our understanding of the regulation of CBF in response to cold stress.