Functional analysis of a wheat pleiotropic drug resistance gene involved in Fusarium head blight resistance

The pleiotropic drug resistance(PDR) sub-family of adenosine triphosphate(ATP)-binding cassette(ABC) transporter had been reported to participate in diverse biological processes of plant. In this study, we cloned three novel PDR genes in Fusarium head blight(FHB) resistant wheat cultivar Ning 7840, which were located on wheat chromosomes 6A, 6B and 6D. In phylogeny, these genes were members of cluster I together with Ae PDR7 and Bd PDR7. Subcellular localization analysis showed that Ta PDR7 was expressed on the plasmalemma. The quantitative real time PCR(RT-PCR) analysis showed that this gene and its probable orthologues in chromosomes 6B and 6D were both up-regulated sharply at 48 h after infected by Fusarium graminearum and trichothecene deoxynivalenol(DON) in spike. When knocking down the transcripts of all Ta PDR7 members by barely stripe mosaic virus-induced gene silencing(BSMV-VIGS) system, it could promote the F. graminearum hyphae growth and made larger pathogen inoculation points in Ning 7840, which suggested that Ta PDR7 might play an important role in response to F. graminearum. Although salicylic acid(SA), methyl jasmonate(Me JA) and abscisic acid(ABA) had been reported to possibly regulate wheat FHB resistance, here, we found that the three members of Ta PDR7 were negatively regulated by these three hormones but positively regulated by indoleacetic acid(IAA).