Molecular cloning and characterization of GhNPR1, a gene implicated in pathogen responses from cotton (Gossypium hirsutum L.)

A novel gene, designated as GhNPR1 (Gossypium hirsutum non-expressor of pathogenesis-related genes 1), was isolated from G. hirsutum (cotton) by RT-PCR (reverse transcription-PCR) and RACE (rapid amplification of cDNA ends). The full-length cDNA was 2108 bp long and had an ORF (open reading frame) that putatively encoded a polypeptide of 592 amino acids, with a predicted molecular mass of 66 kDa. Comparison of this protein sequence with that of Arabidopsis thaliana, Brassica juncea and Nicotiana tabacum showed that the amino-acid homology was 52.98, 52.32 and 54.98% respectively. Analysis of the exon-intron structure of the GhNPR1 gene showed that GhNPR1 consisted of four exons and three introns. Southern-blot analysis revealed that the GhNPR1 was a single-copy gene in cotton. Northern-blot analysis indicated that GhNPR1 was constitutively expressed in all tested tissues, including roots, stems and leaves, with the high expression in stems and leaves. In addition, GhNPR1 was also found to be induced by signalling molecules for plant defence responses, such as methyl jasmonate, salicylic acid and ethylene, as well as attack by pathogens, such as Fusarium oxysporum and Xanthomonas campestris. These results suggest that GhNPR1 may play an important role in the response to pathogen infections in cotton plants.