Abstract
PpC24 is a gene that contains a region homologous to the nucleotide binding site (NBS) characteristic of TIR-NBS-LRR type of disease resistance genes (R genes), but kinase domain, not Toll and interleukin-1 receptor like (TIR) domain expected upstream of the NBS, is predicted in PpC (Akita and Valkonen 2002, J. Mol. Evol. 55:595-605). However, analysis of the genomic sequence of P. patens suggests that there could be a leucine rich repeat (LRR) downstream NBS, as in R proteins. The aim of this study was to obtain additional information about the transcripts produced by PpC24 and to characterize this gene. Analysis of cDNA sequences indicated that PpC24 could be read through until the downstream NBS. Alternative splicing of an intron located between NBS and LRR was also detected. However, there were several stop codons in all reading frames in this region, irrespective whether the intron was spliced or not. The P. patens genome contains at least four PpC24-like sequences, i.e. Kinase-NBS-LRR. We also generated knock-out (KO) mutants from which the kinase region of PpC24 was removed. The morphology of plantlets were not altered on the KO mutants.
