Isolation and Characterization of the PKAr Gene From a Plant Pathogen, Curvularia lunata

By using EST database from a full-length cDNA library of Curvularia lunata, we have isolated a 2.9 kb cDNA, termed PKAr. An ORF of 1,383 bp encoding a polypeptide of 460 amino acids with molecular weight 50.1 kDa, (GeneBank Acc. No. KF675744) was cloned. The deduced amino acid sequence of the PKAr shows 90 and 88 % identity with cAMP-dependent protein kinase A regulatory subunit from Alternaria alternate and Pyrenophora tritici-repentis Pt-1C-BFP, respectively. Database analysis revealed that the deduced amino acid sequence of PKAr shares considerable similarity with that of PKA regulatory subunits in other organisms, particularly in the conserved regions. No introns were identified within the 1,383 bp of ORF compared with PKAr genomic DNA sequence. Southern blot indicated that PKAr existed as a single copy per genome. The mRNA expression level of PKAr in different development stages were demonstrated using real-time quantitative PCR. The results showed that the level of PKAr expression was highest in vegetative growth mycelium, which indicated it might play an important role in the vegetative growth of C. lunata. These results provided a fundamental supporting research on the function of PKAr in plant pathogen, C. lunata.