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

Abstract

Background: Cold stress inhibits normal physiological metabolism in plants, thereby seriously affecting plant development. Meanwhile, plants also actively adjust their metabolism and development to adapt to changing environments. Several cold tolerance regulators have been found to participate in the regulation of plant development. Previously, we reported that BYPASS1-LIKE (B1L), a DUF793 family protein, participates in the regulation of cold tolerance, at least partly through stabilizing C-REPEAT BINDING FACTORS (CBFs). In this study, we found that B1L interacts with TRANSTHYRETIN-LIKE (TTL) protein, which is involved in brassinosteroid (BR)-mediated plant growth and catalyses the synthesis of S-allantoin, and both proteins participate in modulating plant growth and cold tolerance. Results: The results obtained with yeast two hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that B1L directly interacted with TTL. Similar to the ttl-1 and ttl-2 mutants, the b1l mutant displayed a longer hypocotyl and greater fresh weight than wild type, whereas B1L-overexpressing lines exhibited a shorter hypocotyl and reduced fresh weight. Moreover, ttl-1 displayed freezing tolerance to cold treatment compared with WT, whereas the b1l mutant and TTL-overexpressing lines were freezing-sensitive. The b1l ttl double mutant had a developmental phenotype and freezing tolerance that were highly similar to those of ttl-1 compared to b1l, indicating that TTL is important for B1L function. Although low concentrations of brassinolide (0.1 or 1 nM) displayed similarly promoted hypocotyl elongation of WT and b1l under normal temperature, it showed less effect to the hypocotyl elongation of b1l than to that of WT under cold conditions. In addition, the b1l mutant also contained less amount of allantoin than Col-0. Conclusion: Our results indicate that B1L and TTL co-regulate development and cold tolerance in Arabidopsis, and BR and allantoin may participate in these processes through B1L and TTL.

BYPASS1‐LIKE regulates lateral root initiation via exocytic vesicular trafficking‐mediated PIN recycling in Arabidopsis

“…We previously demonstrated that B1L is involved in regulating freezing tolerance in plants (Chen et al, 2019(Chen et al, , 2020. However, other biological functions of B1L have remained unclear.…”

“…We recently revealed that B1L interacts with 14‐3‐3λ to inhibit the degradation of C‐REPEAT BINDING FACTOR3 (CBF3) and positively regulates freezing tolerance in Arabidopsis (Chen et al, 2019). In addition, B1L interacts with TRANSTHYRETIN‐LIKE (TTL) to regulate growth and freezing tolerance (Chen et al, 2020). However, it is unclear whether B1L has other functions.…”

B1L regulates lateral root development by exocytic vesicular trafficking-mediated polar auxin transport in Arabidopsis

“…Our previous studies showed that B1L is involved in the regulation of freezing tolerance in plants (Chen et al, 2019; Chen et al, 2020); however, other biological functions of B1L remain unclear. In this study, we revealed a novel biological function and the elegant underlying molecular mechanism of B1L-mediated regulation of lateral root formation.…”

“…(Chen et al, 2019). In addition, B1L interacts with TRANSTHYRETIN-LIKE (TTL) to regulate growth and freezing tolerance (Chen et al, 2020). However, to the best of our knowledge, no study has been yet reported on the other molecular functions of B1L.…”

McMYB4 improves temperature adaptation by regulating phenylpropanoid metabolism and hormone signaling in apple

“…Furthermore, the TRANSTHYRETIN-LIKE (TTL) ttl-1 mutant promoted freezing tolerance. Therefore, B1L overexpression promoted plant freezing tolerance by interacting with TTL 19 . BR could also positively regulate the net photosynthetic rate and stomatal conductance under low-temperature treatment (8 °C), which promoted the growth and development of tung trees 20 .…”