Evaluation of differential expression of homospermidine synthase (HSS1) gene in different tissues of medicinal plant Senecio vulgaris L

Abstract

Objective Homospermidine synthase (HSS) is the first enzyme in the specific pathway of pyrrolizidiene alkaloid (PA). HSS catalyzes the NAD1-dependent transfer of an aminobutyl group of spermidine to putrescine. Putrescine, spermidine and spermine are three polyamines which are naturally positively charged compounds found in virtually all living cells. These compounds bind to DNA and have been implicated in a number of crucial processes such as cell division, differentiation and membrane function. Very few studies on expression of homospermidine synthase gene in Senecio vulgaris, particularly in natural conditions have been reported. The objective of current research was to study homospermidine synthase gene expression in different tissues of S. vulgaris by real-time PCR. Material and methods The total RNA was extracted from roots, shoots (stems and leaves) and flowers, and was converted to cDNA. Specific primers were designed for HSS1 gene and also for the Pol II which was applied as a reference housekeeping gene in the experiment and expression level of HSS1 was assessed using real-time PCR. Results Melting curves of two genes showed the specificity of PCR amplification. Evaluation of normalized expression level of HSS1 gene showed that the gene was differentially expressed in different tissues of S. vulgaris. Maximum relative expression (>59-fold change relative to Pol II reference gene) was observed in roots where the homospermidine synthase is activated and homospermidine is produced. Interestingly, the gene is also expressed in flowers but with a lower extent (4-fold change relative to housekeeping Pol II gene). As expected the gene showed non-significant relative expression in shoots where the homospermidine is transported. Conclusions Expression of HSS1 gene in S. vulgaris is tissue-specific and is higher in the roots relative to other tissues.

Keywords

• homospermidine synthase
• gene expression
• natural condition
• real-time pcr
• senecio vulgaris