Molecular cloning and expression characteristics of a novel MAPKKK gene, GhCTR1, from cotton (Gossypium hirsutum L.)

Signaling through MAPK (mitogen-activated protein kinase) cascades plays critical roles in plant development, defense and stress responses. In the present study, a novel MPKKK gene, nominated as GhCTR1, was isolated from the economic crop cotton (Gossypium hirsutum L.). Sequence analysis revealed that the full-length cDNA of GhCTR1 is 3347 bp in length and encodes an 851-amino acid protein with the conserved ATP-binding site and Ser/Thr kinase active site. Fourteen introns were observed in the genomic DNA sequence, and the last one was located in the 3′ untranslated region (UTR). To investigate the expression patterns of GhCTR1, semi-quantitative RT-PCR was performed. The expression of GhCTR1 was higher in the roots and stems than in the leaves. Moreover, GhCTR1 was upregulated by signaling molecules, including salicylic acid (SA), gibberellins (GAs) and abscisic acid (ABA). Drought, wounding and Rhizoctonia solani infection also increased GhCTR1 transcription. However, there was no remarkable difference in GhCTR1 expression after treatment with methyl jasmonate (MeJA), ethylene (ET), H2O2, salt or cold. Additionally, analysis of a 439-bp GhCTR1 promoter fragment revealed several putative cis-acting elements that may be responsible for the enhanced response to phytohormones and stress. These results suggest that GhCTR1 may be involved in SA-, GA- and ABA-mediated signaling pathways to provide resistance to biotic and abiotic stress.

► Cis-acting elements related to SA, GA and MeJA responsiveness were predicted.
► GhCTR1 may response to various stresses through SA, ABA or GA signaling pathways.
► It will be a good step in understanding the complicated MAPK signaling networks.