Abstract:

The gene encoding XYNB with high specific activity from Streptomyces olivaceoviridis A1 was expressed in tobacco plant under the control of an efficient double 35S promoter and AMV enhancer. The integration of the xynB in the genome of tobacco was confirmed by PCR detection of T₀ and T₁ plants. ELISA, SDS-PAGE and Western blot analysis confirmed the presence of XYNB enzyme. High levels of the 20.8 kD protein(Fig.4 and Fig.5)，which was as same as that of original xylanase (XYNB)， was synthesized in cytoplasm or targeted to the intercellular space by means of the potato proteinase inhibitorⅡ signal peptide. The recombinant xylanase was accumulated to the level of up to 6% of total soluble leaf proteins. And in transgenic leaf tissues, xylanase activity up to 170 IU/g fresh leaf (23 IU·mg^-1 total protein) was observed. Furthermore, growth and development of the transgenic plants was not affected by the expression of foreign enzyme, and T₁ plants showed the genetic stability. The results demonstrated that transgenic plants can be used to produce high activity recombinant xylanase efficiently, and can be as the alternative of custom feed additives.

Key words: Xylanase, High specific activity, Transgenic plant, Tobacco