A novel dirigent protein gene with highly stem-specific expression from sugarcane, response to drought, salt and oxidative stresses.

Dirigent and dirigent-like family proteins contain a number of proteins involved in lignification or in the response to pathogen infection and abiotic stress in plants. In the present study, a full-length cDNA sequence of a dirigent-like gene designated ScDir (GenBank Accession Number JQ622282) was obtained from sugarcane based on the stem full-length cDNA library. The ScDir gene was 819-bp long, including a 564-bp ORF encoding 187 amino acid residues. The protein N-terminus contained signal peptides at amino acid residues of 1-25 and transmembrane regions at 7-26 aa. A his-tagged ScDir protein with an estimated molecular mass of 27.4 kDa was expressed in Escherichia coli system. The expressed ScDir protein had increased the host cell's tolerance to PEG and NaCl. When an endogenous GAPDH gene was used as internal control, results from real-time qPCR demonstrated that the ScDir mRNA amount in sugarcane stems was significantly higher than that in the roots, leaves and buds by 18.64 ± 0.48, 25,635.16 ± 2,966.03 and 721.50 ± 8.17-fold, respectively. The ScDir transcript levels in sugarcane seedling increased under H(2)O(2), PEG or NaCl stress. The expression level of ScDir was significantly upregulated under PEG stress, and the highest level was observed at 12 h after stress. Thus, both the ScDir-hosted cell performance and the enhanced expressions in sugarcane imply that the ScDir gene is involved in the response to abiotic stresses of drought, salts and oxidation. The transcription of the ScDir gene is highly stem-specific, as revealed by real-time qPCR. Key message A novel sugarcane Sc-Dir gene, DIRd subfamily, which is highly stalk-specific expression and involved in the response to artificial stresses of drought, salts, and oxidatives.