Transcriptome Analysis of the Defense Response of Roses in the Interaction with Diplocarpon rosae and Podosphaera pannosa using the MACE Technique

Roses are the economically most important ornamental plants worldwide. Besides the research on horticultural important traits like flower color or scent, the defense response against pathogens comes into focus more and more.

The presented work deals with the defense responses of roses against two major fungal pathogens Diplocarpon rosae and Podosphaera pannosa. These interaction systems are of particular interest because of the different lifestyles of the pathogens. D. rosae is a hembiotrophic ascomycet, whereas P. pannosais an obligate biotrophic ascomycet.

We performed a transcriptome analysis with the new MACE (Massive Analysis of cDNA Ends) technique to obtain data for three interaction systems: a compatible interaction of the susceptible rose variety “Pariser Charme” inoculated with P. pannosa, a compatible interaction of “Pariser Charme” with D. rosae and an incompatible interaction of the resistant genotype 91/100-5 with D. rosae.

Non-infected “Pariser Charme” leaves were used as controls. Samples for three different time points (0, 24, 72 hpi) were taken and all inoculation experiments have been performed three times independently. All in all, we sequenced 33 libraries and obtained an average of 12.7 million reads per library where the read count ranged from 6.2 to 32.3 million reads. 

The first results indicate that typical defense responses are visible in all interaction systems. We could also identify sequences which are specifically induced as response to either one of the pathogens or to the resistance reaction in the incompatible interaction. Additionally, we could isolate fungal sequences of both pathogens.