RNA sequence analysis data of maintained on onions.

(Berk.) is an important biotrophic oomycete that causes downy mildew on onion ( L.) worldwide, especially in humid and temperate regions. The disease attacks bulb and seed production of onion, resulting in losses in yield and quality of bulbs. Epidemiological studies have increased our understanding and control of downy mildew on onion; however, little is known about the molecular aspects of behavior during infection. Here, we isolated RNA from four samples of sporangia and sporangiophores of , which were maintained by spore inoculation onto onions in a growth chamber. We then used an Ion PGM next generation sequencer to acquire and assemble the RNA sequences of . By transcriptome shotgun assembly, we obtained 2335 contigs (N50, 884 nucleotides (nt); mean length, 881.6 nt). The data are accessible at NCBI (BioProject PRJNA391849). Our data resource will facilitate further studies of the molecular events during infection.