Cloning and expression analysis of polygalacturonase-inhibiting protein gene from Panax notoginseng / 中草药

ABSTRACT

Objective: To clone the full-length cDNA sequence of PnPGIP gene encoding polygalacturonase-inhibiting protein (PGIP) from Panax notoginseng and analyze the expression levels of PnPGIP. Methods: Based on P. notoginseng expressed sequence tag (EST) encoding PGIP, specific primers were designed and the full-length cDNA of EST was cloned with the method of rapid amplification of cDNA ends (RACE). The expression levels of PnPGIP were analyzed by qRT-PCR. Results: The full-length cDNA of PnPGIP was 1 171 bp and contained an intact open reading frame (ORF) of 981 bp, a 13 bp 5'-untranslated region (UTR), and a 177 bp 3'-UTR. The deduced amino acid sequence of PnPGIP has 326 amino acid residues which form a 36 770 polypeptide with a calculated pI of 5.83. qRT-PCR analysis indicated that the expression of PnPGIP was quickly induced after inoculation with Fusarium solani and Alternaria panax, and the highest transcription level was achieved at 4 h and 2 h post inoculation, respectively. Moreover, the expression of PnPGIP was induced in different degrees by methyl jasmonate (MeJA), ethylene (ETH), H2O2, and salicylic acid (SA). Conclusion: PnPGIP responds to F. solani and A. panax infection in the transcription level, and it is induced by several kinds of adversity stresses related signaling molecules. Therefore, PnPGIP may be involved in defense response of P. notoginseng against F. solani and A. panax.