RESUMO
Superoxide dismutase (SOD) is a key enzyme that scavenge superoxide anion free radical (O2·-) in vivo, and plays an important role in plant growth and development and stress. In this study, according to the genome and transcriptome data of Salvia miltiorrhizae, 9 SOD genes were identified and the expression patterns of SOD family genes were further analyzed, including 5 Cu/Zn-SOD, 2 Fe-SOD and 2 Mn-SOD. On the basis of proteomic analysis, combined with transcriptome data, one full-length cDNA of Mn-SOD gene, namely SmMSD2 was cloned from Salvia miltiorrhizae. The results of amino acid sequence alignment and phylogenetic analysis showed that SmMSD2 protein belongs to the manganese superoxide dismutase (Mn-SOD) subfamily, and SmMSD2 protein shares high sequence identity with the Mn-SOD proteins of various plants that all contain a C-terminal conserved metal-binding domain "DVWEHAYY". The prokaryotic expression vector pMAL-c2X-SmMSD2 was constructed and transformed into E. coli BL21 expressing strain, and the target recombinant protein was successfully induced and its enzymatic properties were analyzed. Spatiotemporal expression analysis showed that SmMSD2 gene was expressed in all tissues, indicating that SmMSD2 gene was constitutively expressed at a stable level. Real-time quantitative PCR indicated that drought (15% PEG6000), abscisic acid (ABA) and indole-3-acetic acid (IAA) could induce the expression of SmMSD2 gene, suggesting that SmMSD2 may be involved in the response of Salvia miltiorrhizae to abiotic stress such as drought, as well as the signaling pathways of phytohormone ABA and IAA. These results lay the foundation for further elucidating the involvement of superoxide dismutase in the stress response and accumulation of active components of Salvia miltiorrhiza.
RESUMO
In order to reveal the molecular mechanism of the small heat shock proteins (sHSPs) involved in stress resistance and active ingredients accumulation in Salvia miltiorrhiza, a small heat shock protein gene was cloned from Salvia miltiorrhiza by reverse transcription PCR according to the transcriptome data of orange root Salvia miltiorrhiza. The gene is named SmHSP21.8 based on the molecular weight of the protein, and it contains an open reading frame of 585 bp, which encodes 194 amino acids. The results of phylogenetic analysis and amino acid sequence alignment showed that SmHSP21.8 protein belongs to the endoplasmic reticulum (ER) subfamily, and contains a conserved endoplasmic reticulum-specific DPFR-I/V-LE-H/Q-x-P motif at N-terminus. The prokaryotic expression vector pMAL-c2X-SmHSP21.8 was constructed and transformed into E. coli BL21 competent cells. The recombinant protein was successfully expressed after inducted. Temporal and spatial expression analysis showed that SmHSP21.8 gene was the highest expressed in flowers and had significant tissue specificity. The relative expression of the gene was significantly increased in seedlings after induction by 38 ℃, PEG6000, abscisic acid(ABA), and indole-3-acetic acid (IAA), indicating that SmHSP21.8 gene may be involved in abiotic stress such as high temperature and drought, as well as the response to exogenous hormones ABA and IAA. These results lay the foundation for further research on the molecular mechanism of small heat shock proteins involved in adversity stress.