Genome-wide identification, phylogeny, and expression analysis of Sec14-like PITP gene family in sugarcane.

KEY MESSAGE: Six Sec14-like PITP genes from sugarcane were identified, two of them were cloned, and their biological functions were characterized indicating their involvement in plant defense against biotic and abiotic stresses. Sec14, a phosphatidylinositol transfer protein (PITP) is widely present in eukaryotes. In this study, the structure and expression patterns of six Sec14-like PITP genes (ScSEC14-1, ScSEC14p, ScSFH1, ScSFH2, ScPATL1, and ScPATL2) from sugarcane were analyzed, and two of them (ScSEC14-1 and ScSEC14p) were cloned and functionally verified. Phylogenetic analysis divided these genes into four groups, including group I (ScSFH1 and ScSFH2), group II (ScPATL1 and ScPATL2), Group III (ScSEC14p), and group V (ScSEC14-1). qRT-PCR analysis showed tissue-specific expression of these genes, primarily in the root, leaf, and bud tissues. They responded differently to SA, MeJA, and ABA stresses. ScSEC14-1, ScSEC14p, and ScSFH2 were upregulated by CuCl2 and CdCl2, while ScSEC14-1, ScSFH1, ScSFH2, and ScPATL1 were upregulated by PEG and NaCl. When infected by Sporisorium scitamineum, the transcripts of ScSFH1, ScSFH2, ScPATL1, and ScPATL2 were upregulated in the resistant genotype Yacheng 05-179, while those of ScSEC14-1 and ScSEC14p were upregulated in the susceptible genotype ROC22. Subcellular localization showed that ScSEC14-1 and ScSEC14p were mainly localized in the plasma membrane and cytoplasm. Enhanced growth of Escherichia coli BL21 cells expressing ScSEC14-1 and ScSEC14p showed high tolerance to NaCl and mannitol stresses. The transient overexpression of ScSEC14-1 and ScSEC14p in Nicotiana benthamiana leaves enhanced its resistance to the infection of tobacco pathogens Ralstonia solanacearum and Fusarium solani var. coeruleum. We can conclude the involvement of ScSEC14-1 and ScSEC14p in the defense against biotic and abiotic stresses, which should facilitate further research on Sec14-like PITP gene family, especially its regulatory mechanisms in sugarcane.

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.