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The N gene, a member of the Toll-IL-1 homology region–nucleotide binding site–leucine-rich repeat region (LRR) class of plant resistance genes, encodes two transcripts, N_S and N_L, via alternative splicing of the alternative exon present in the intron III. The N_S transcript, predicted to encode the full-length N protein containing the Toll-IL-1 homology region, nucleotide binding site, and LRR, is more prevalent before and for 3 hr after tobacco mosaic virus (TMV) infection. The N_L transcript, predicted to encode a truncated N protein (N^tr) lacking 13 of the 14 repeats of the LRR, is more prevalent 4–8 hr after TMV infection. Plants harboring a cDNA-N_S transgene, capable of encoding an N protein but not an N^tr protein, fail to exhibit complete resistance to TMV. Transgenic plants containing a cDNA-N_S-bearing intron III and containing 3′ N-genomic sequences, encoding both N_S and N_L transcripts, exhibit complete …