Cloning and expression analysis of soluble acid invertase gene from Dendrobium officinale

Objective To clone soluble acid invertase (SAI) gene in Dendrobium officinale, and perform bioinformatics and spatio-temporal expression analysis.

Method The full length cDNA of SAI gene in D. officinale was cloned based on homologous sequences, the sequences were analyzed using bioinformatics tools, and the tissue-specific expressions were analyzed using qRT-PCR.

Result The full length SAI gene in D. officinale is 1 595 bp, the full length cDNA is 1 368 bp, and the Genbank accession number is KU598852.The SAI gene encodes 455 amino acids, and the protein molecular mass is 50 700. NCBI BLASTx results show that the D. officinale acid invertase gene has 77% similarity with Citrus unshiu acid invertase gene and C. sinensis acid beta-fructofuranosidase gene, and has above 68% similarity with acid invertase genes from other plants. Cluster analysis shows that D. officinale acid invertase gene has the closest genetic relationship with Zea mays vacuolar invertase gene and sugarcane (Saccharum officinarum) SAI gene. The encoded protein of D. officinale SAI gene is positioned in vacuole, and is a hydrophilic, non-transmembrane and heat-stable protein. RT-PCR results showed that the expression level of SAI gene was the highest in 2-year-old D. officinale stems, and the lowest in 3-year-old D. officinale leaves.

Conclusion The cloned gene is identified as the D. officinale vacuolar SAI gene. Its expression has great differences among different tissues and at different developmental stages.