Abstract
BackgroundThe basic helix-loop-helix (bHLH) proteins, a large transcription factors family, are involved in plant growth and development, and defensive response to various environmental stresses. The resurrection plant Myrothamnus flabellifolia is known for its extremely strong drought tolerance, but few bHLHs taking part in abiotic stress response have been unveiled in M. flabellifolia.ResultsIn the present research, we cloned and characterized a dehydration-inducible gene, MfbHLH38, from M. flabellifolia. The MfbHLH38 protein is localized in the nucleus, where it may act as a transcription factor. Heterologous expression of MfbHLH38 in Arabidopsis improved the tolerance to drought and salinity stresses, as determined by the studies on physiological indexes, such as contents of chlorophyll, malondialdehyde (MDA), proline (Pro), soluble protein, and soluble sugar, water loss rate of detached leaves, reactive oxygen species (ROS) accumulation, as well as antioxidant enzyme activities. Besides, MfbHLH38 overexpression increased the sensitivity of stomatal closure to mannitol and abscisic acid (ABA), improved ABA level under drought stress, and elevated the expression of genes associated with ABA biosynthesis and ABA responding, sucha as NCED3, P5CS, and RD29A.ConclusionsOur results presented evidence that MfbHLH38 enhanced tolerance to drought and salinity stresses in Arabidopsis through increasing water retention ability, regulating osmotic balance, decreasing stress-induced oxidation damage, and possibly participated in ABA-dependent stress-responding pathway.
Highlights
The basic helix-loop-helix proteins, a large transcription factors family, are involved in plant growth and development, and defensive response to various environmental stresses
Cloning and sequence analysis of MfbHLH38 Using PCR amplification, the cDNA sequence of MfbHLH38 was obtained from M. flabellifolia
We further performed phylogenetic analysis and found that the MfbHLH38 was most homologous to VvORG2, PtORG2, HbORG2-like, JcORG2 (ORG2 named bHLH38), and AtbHLH38 which are from Vitis vinifera, Populus trichocarpa, Hevea brasiliensis, Jatropha curcas, and Arabidopsis thaliana, respectively. (Fig. 1b)
Summary
The basic helix-loop-helix (bHLH) proteins, a large transcription factors family, are involved in plant growth and development, and defensive response to various environmental stresses. The basic helix-loop-helix (bHLH) transcription factors belong to a large superfamily It could be subdivided into 26 subsections and participates in multiple transcriptional regulatory pathways [7]. The bHLH transcription factors are characterized by a highly conserved bHLH domain, comprising of a basic region at its N-terminus and an HLH region following closely. These two regions function as DNA binding and promoting protein-protein interactions, respectively [11, 12]. The core DNA sequence element of target genes recognized by the bHLH proteins is a consensus motif called the E-box (5′-CANN TG-3′), with the palindromic G-box (5′-CACGTG-3′) being one of the most common forms [13, 14]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call