Abstract:
Objective Functions of DcbHLH14, a basic helix-loop-helix transcription factor of Dendrobium catenatum Lindl., in response to abiotic stresses were studied.
Method DcbHLH14 was cloned from D. catenatum leaves using homologous cloning method for a bioinformatic analysis on the gene and expression in tissues. Gene expressions under low temperature, drought, and abscisic acid (ABA) stresses were determined.
Result The ORF of DcbHLH14 was 1 269 bp and encoded 422 amino acids. It contained one exon, no intron, and 7 bases that were different from the reference sequences. The theoretical molecular weight was 45.8 kD, isoelectric point pH 5.98, and molecular formula C2011H3192N586O613S13. Its conserved domains contained bHLH-MYC-N and HLH proteins that had high similarities with the bHLH proteins in D. chrysotoxum at 97.16% and in Cymbidium goeringii at 86.90%. The transcriptome analysis revealed high expressions in the flower buds and columns but low in the leaves of the wild D. catenatum from Yunnan, whereas the qRT-PCR analysis showed high expressions in the leaves and low in the stems of the sample from Danxia, Guangdong. The promoters of DcbHLH14 contained numerous cis-acting elements associated with the responses to water-depletion, low temperature, dehydration, and ABA stresses, which significantly affected expression of the gene. For instance, DcbHLH14 was upregulated to peak in 6 h after a low temperature or ABA treatment reaching 12.6 or 3.7 times, respectively, as well as by a 9 h drought stress to become as high as 6.5 times of control.
Conclusion It was postulated that DcbHLH14 responded to low temperature or drought stress through the ABA signaling pathway at transcription level. Hence, the tolerance of D. catenatum to the abiotic stresses could be manipulated by regulating the expression of the downstream functional gene.
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