The antagonistic basic helix-loop-helix partners BEE and IBH1 contribute to control plant tolerance to abiotic stress

MORENO-PIOVANO, GUILLERMO; CHAN, RAQUEL L.; MORENO, JAVIER E.

PLANT SCIENCE

ELSEVIER IRELAND LTD

Año: 2018 vol. 271 p. 143 - 150

0168-9452

The bHLH family is composed by canonical andnon-canonical transcription factors (TFs) that differ in the presence orabsence of their DNA-binding domain, respectively. Since both types of bHLHproteins are able to dimerize, their relative abundance impacts theirbiological activity. Among this TF family BEE and IBH are canonical andnon-canonical bHLHs, respectively and previous reports indicated that BEE2 and IBH1dimerize. Wondering whether BEE TFs participate in the abiotic stress responseand how the dimerization with IBH1 could regulate their role in Arabidopsis,double bee1/bee2 and triple bee1/bee2/bee3 mutants were tested undersalinity and drought stresses. The bee1/bee2/bee3mutant showed an enhanced tolerance whereas the double mutant behavedsimilar to wild type plants. These results indicated that BEE genes play a role in the stress response and also put inevidence the redundancy within the BEE family. Moreover, ectopic expression of IBH1 on different mutant backgroundsimproved plant tolerance to abiotic stress, independently of the background.However, the yield of these transgenic plants was penalized with abortive seeds.Our results suggest that BEE genesare negative regulators of physiological responses to abiotic stress whereasIBH1 is a positive modulator via different pathways, one of them involving BEETFs.