Biolistic transformation of Haematococcus pluvialis with constructs based on the flanking sequences of its endogenous alpha tubulin gene

The complete sequence information of the alpha tubulin ( tub ) genes was obtained from both Haematococcus pluvialis NIES144 and SCCAP K0084., Putative transcriptional elements and polyadenylation signals were identified respectively in their 5’ and 3’ flanking regions. Three selection cassettes of tub/aadA, tub/hyr and tub/ble with 3 different antibiotic-resistant genes fused between the 5’ and 3’ flanking sequences of the tub gene were constructed and utilized for biolistic transformation of H.pluvialis . Antibiotic resistant transformants were obtained in the bombardments with the tub/aadA cassette in 2 strains. It was found that, the foreign tub/aadA DNA could be completely transferred and inherited in their genome through non-homologous recombination. Moreover, transcripts of the insert and spectinomycin resistance were identified. Transformation efficiencies up to 3×10 -5 per μg DNA could be obtained in H.pluvialis NIES144 or SCCAP K0084 through utilization of a culture with a high percentage of flagellate cells and by optimizing bombarding protocol. The presented selection marker and optimized transforming procedures in this report should strengthen the platform technology for genetical manipulation and modification of H.pluvialis .