Cloning and Characterization of Full Length cDNA of a CC-NBS-LRR Resistance Gene in Sweetpotato

Conserved domain such as nucleotide binding site (NBS) was found in several cloned plant disease resistance genes. Based on the NBS domain, resistance gene analogues (RGAs) have been isolated. A full-length cDNA, SPR1 was obtained by rapid amplification of cDNA ends (RACE) method. Sequence analysis indicated that the length of SPR1 was 3 066 bp, including a complete open reading frame of 2 667 bp encoding SPR1 protein of 888 amino acids. Compared with known NBS-LRR genes, it presented relatively high amino acid sequence identity. The polypeptide has a typical structure of nonTIR-NBS-LRR genes, with NB-ARC, CC, and LRR domains. The SPR1-related sequences belonged to multicopy gene family in sweetpotato genome according to the result of Southern blotting. Semi-quantitative RT-PCR analysis showed SPR1 expressed in all tested tissues. The cloning of putative resistance gene from sweetpotato provides a basis for studying the structure and function of sweetpotato disease-resistance relating genes and disease resistant genetic breeding in sweetpotato. The gene has been submitted to the GenBank database, and the accession number is EF428453.