Cloning And Expression Analysis Of Stachyose Synthase Gene In Brassica Napus L.

The seed desiccation tolerance is integrative characteristic forming during the process of developing and an important criterion of determining seed storage characteristic. Orthodox seeds lose most of their water after maturation. Seeds acquire desiccation tolerance during development to protect themselves against the harmful dehydration. The acquisition of desiccation tolerance has been shown to be correlated with the accumulation of raffinose family oligosaccharides (RFO).In the biosynthesis of the RFO proceeds, stachyose synthase transfers a galactose moiety from galactionl to raffinose, yielding stachyose. Recent studies have shown that stachyose may play a more important role during some seeds development and make them to avoid the dehydration injury, but the specific role is still obscure. Seeds of oil rape (Brassica napus L.) are excellently tolerant to desiccation. In this study, a full-length cDNA sequence of stachyose synthase gene(BnSTS) was obtained from the oil rape cultivar’Deyou5’for the first time using RT-PCR and RACE, GenBank accession No. HQ285880.1. The full length of BnSTS is3210bp, and the ORF is2619bp, encoding873amino acids. Prokaryotic expression showed the recombinant plasmid can express the prospective proteins, and the molecular weight is97.6kD.The nickel ion affinity chromatography technology was used to separate and purify the target protein. Then, gene expression level during seeds maturation was analysed by the Real-Time PCR.Results indicated that BnSTS expression level and the concentration of stachyose in different development stage of seeds were associated. Gene expression and the acquirement of desiccation tolerance of seeds also had a time consistency trend. The over-expression and anti-sense vectors of BnSTS gene were constructed, aiming for functional analysis of BnSTS via transgenic plants. This study has laid an important foundation for the further research of this gene regulatory role in seeds desiccation tolerance mechanism.