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 BYPASS1-LIKE modulates freezing tolerance through the CBFs in Arabidopsis . The expression of B1L was rapidly induced under cold treatment. Comparing to wild type, B1L knockout mutants were more sensitive to freezing treatment, whereas B1L-overexpressing lines were more tolerant. The expression of CBF s and CBF target genes was significantly decreased in b1l 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 b1l mutation promoted the degradation of CBF3 compared to wild type, whereas 14-3-3κλ mutant and b1l 14-3-3κλ mutant suppressed the degradation of CBF3. Consistently, 14-3-3κλ and b1l 14-3-3κλ 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.

TRANSTHYRETIN-LIKE and BYPASS1-LIKE co-regulate growth and cold tolerance in Arabidopsis

“…The b1l mutant was more sensitive to freezing than the wild type under cold-acclimation (CA) conditions (Fig. 4a, b), as in our previous results [33], whereas the ttl-1 mutant was more tolerant to freezing temperature than the wild type under non-acclimation (NA) conditions ( Fig. 4c, d).…”

“…To investigate the biological function of B1L in Arabidopsis, we used a yeast two-hybrid (Y2H) screening system to select B1L-interacting proteins previously [33], and TTL was selected as one of the candidate proteins. In this study, Y2H and bimolecular fluorescence complementation (BiFC) assays were performed to confirm the interaction between B1L and TTL.…”

“…b1l knockout mutant displayed promoted seedling growth, whereas B1L-overexpressing lines exhibited retarded growth A B1L T-DNA insertion line (b1l) and a B1L-overexpressing line (B1L-OE), which had been used in our previous study [33], were used to ascertain whether B1L also participates in these seedling growth processes. One-week-old b1l mutants displayed a promoted developmental phenotype compared with wild type seedlings, whereas B1L-OE exhibited an adverse phenotype (Fig.…”

“…As B1L was previously found to modulate plant freezing tolerance [33], whether TTL was able to participate in the regulation of freezing tolerance was investigated. The b1l mutant was more sensitive to freezing than the wild type under cold-acclimation (CA) conditions (Fig.…”

“…Previously, we found that BYPASS1-LIKE (B1L) acts as a positive regulator in the tolerance of plants to freezing [33]. B1L interacts with 14-3-3λ, resulting in a reduction in the degradation of CBFs that improves the freezing tolerance of Arabidopsis [33]. B1L belongs to the DUF793 protein family, which contains at least 12 proteins, including AT1G74450 and BYPASS1.…”