Transcriptome analysis using RNA sequencing of three endemic Myrtaceae species from New Caledonia displaying contrasting responses to myrtle rust (Austropuccinia psidii) [SYZLO-EUCGR]

Finding predictive molecular markers for resistance against Myrtle rust may help to identify resistant plants and provide a means of maintaining Myrtaceae production in nursery, especially for ecosystems restoration purposes. Sequence polymorphism involving in differentiate expressed genes are particularly relevant for disease resistance marker design. We sequenced the transcriptomes of resistant and susceptible individuals of three endemic host species: Arillastrum gummiferum, Tristaniopsis glauca and Syzygium longifolium. The rust phenotype of the individuals of each species was defined as "infected" (considered as susceptible) and "healthy" (considered as resistant). We described here a pre-breeding methodology to find disease resistance markers by combining next-generation sequencing, differential gene expression (DGE) and SNP calling. DGE was conducted in parallel using the only one available sequenced Myrtaceae genome (Eucalyptus grandis) and a de novo assembly transcriptome from each species. The edgeR tests if a gene is DE between “infected” individuals versus “healthy” ones. If the fold change log (FC = infected/healthy) is greater than 0, the gene is thus overexpressed in the infected individuals (considered as susceptible). Overall design: Seven individuals of Syzygium longifolium (five healthy/two infected)