[Identification of GeERF transcription factors in Gelsmium elegans and their expression under low temperature stress].

With prominent medicinal value, Gelsemium elegans has been overexploited, resulting in the reduction of the wild resource. As a result, artificial cultivation turns out to be a solution. However, this medicinal species is intolerant to low temperature, and thus genes responding to the low temperature are important for the cultivation of this species. Based on the transcriptome database of G. elegans at 4 ℃, 29 differentially expressed GeERF genes were identified. Bioinformatics analysis of 21 GeERF gene sequences with intact open reading frames showed that 12 and 9 of the GeERF proteins respectively clustered in DREB subgroup and ERF subgroup. GeDREB1 A-1-GeERF6 B-1, with molecular weight of 23.78-50.96 kDa and length of 212-459 aa, were all predicted to be hydrophilic and in nucleus. Furthermore, the full-length cDNA sequence of GeERF2B-1 was cloned from the leaves of G. elegans. Subcellular localization suggested that GeERF2B-1 was located in the nucleus. According to the quantitative reverse-transcription PCR(qRT-PCR), GeERF2B-1 showed constitutive expression in roots, stems, and leaves of G. elegans, and the expression was the highest in roots. In terms of the response to 4 ℃ treatment, the expression of GeERF2B-1 was significantly higher than that in the control and peaked at 12 h, suggesting a positive response to low temperature. This study lays a scientific basis for the functional study of GeERF transcription factors and provides gene resources for the improvement of stress resistance of G. elegans.

Molecular cloning and characterization of two pathogenesis-related ß-1,3-glucanase genes ScGluA1 and ScGluD1 from sugarcane infected by Sporisorium scitamineum.

KEY MESSAGE: Two ß-1,3-glucanase genes from sugarcane were cloned and characterized. They were all located in apoplast and involves in different expression patterns in biotic and abiotic stress. Smut caused by Sporisorium scitamineum is a serious disease in the sugarcane industry. ß-1,3-Glucanase, a typical pathogenesis-related protein, has been shown to express during plant-pathogen interaction and involves in sugarcane defense response. In this study, ß-1,3-glucanase enzyme activity in the resistant variety increased faster and lasted longer than that of the susceptible one when inoculated with S. scitamineum, along with a positive correlation between the activity of the ß-1,3-glucanase and smut resistance. Furthermore, two ß-1,3-glucanase genes from S. scitamineum infected sugarcane, ScGluA1 (GenBank Accession No. KC848050) and ScGluD1 (GenBank Accession No. KC848051) were cloned and characterized. Phylogenetic analysis suggested that ScGluA1 and ScGluD1 clustered within subfamily A and subfamily D, respectively. Subcellular localization analysis demonstrated that both gene products were targeted to apoplast. Escherichia coli Rosetta (DE3) cells expressing ScGluA1 and ScGluD1 showed varying degrees of tolerance to NaCl, CdCl2, PEG, CuCl2 and ZnSO4. Q-PCR analysis showed up-regulation of ScGluA1 and slight down-regulation of ScGluD1 in response to S. scitamineum infection. It suggested that ScGluA1 may be involved in the defense reaction of the sugarcane to the smut, while it is likely that ScGluD1 was inhibited. The gene expression patterns of ScGluA1 and ScGluD1, in response to abiotic stresses, were similar to sugarcane response against smut infection. Together, ß-1,3-glucanase may function in sugarcane defense mechanism for S. scitamineum. The positive responses of ScGluA1 and the negative responses of ScGluD1 to biotic and abiotic stresses indicate they play different roles in interaction between sugarcane and biotic or abiotic stresses.