Increasing transient expression of CAT gene in Porphyra haitanensis by Matrix attachment regions and 18S rDNA targeted homologous recombination

To test whether matrix attachment regions (MARs) and 18S rDNA can influence CAT gene transient expression positively in the red algae Porphyra haitanensis, a targeting vector pHR-CAT containing a portion of the 18S rDNA from P. haitanensis, pMAR1-HR-CAT containing one MAR from silkworm and a portion of the 18S rDNA from P. haitanensis and pMAR2-HR-CAT containing two MARs from silkworm and a portion of the 18S rDNA from P. haitanensis were constructed. With the electroporation method, the vectors were transferred into the protoplasts from the thalli of P. haitanensis. The results showed that the expression of chloramphenicol acetyl transferase (CAT) protein in transformed cells reached a maximum at 96 h after transformation. It was increased markedly with the pMAR2-HR-CAT compared with the pHR-CAT or the pCAT(@)3-control vector (P < 0.01), and it was increased inconspicuously with pHR-CAT compared with the pCAT(@)3-control vector (P > 0.05). It is suggested that MAR from silkworm could enhance the transient expression of foreign genes in P. haitanensis.