Molecular Cloning and Characterization of an Ortholog of NPR1 Gene from Dongguan Dajiao (Musa spp. ABB)

The nonexpresser of pathogenesis-related gene 1 (NPR1) plays a pivotal role in systemic acquired resistance in plants. In this study, a novel full-length NPR1-like gene, designated MdNPR1 (accession number FJ357442), was isolated by RACE-PCR from cv. Dongguan Dajiao (Musa spp. ABB), a local banana cultivar known to be resistant to Fusarium oxysporum fsp. cubense (FOC) race 4. Sequence alignment showed that MdNPR1 contained an ankyrin repeat domain and a broad complex, tramtrack, and bric-a-brac (BTB) domain. Semiquantitative reverse transcription polymerase chain reaction revealed that MdNPR1 could be constitutively expressed at low levels in both of the FOC race 4-susceptible cultivar Fenjiao (Musa spp. ABB) and the resistant cultivar Dongguan Dajiao. However, MdNPR1 could be induced by exogenous application of salicylic acid in cv. Dongguan Dajiao, but not in cv. Fenjiao. Moreover, the accumulated level of MdNPR1 transcripts in cv. Dongguan Dajiao was higher than that in cv. Fenjiao when plants were treated with FOC race 4 inoculation. Our results implied that MdNPR1 might represent as a promising candidate for engineering resistant to broad-spectrum pathogen in banana.