asiri.padukkav@postgrad.curtin.edu.au

The yield loss of wheat due to Septoria nodorum blotch (SNB) is up to 31% worldwide and it is ranges from 5-15% in Western Australia. Causative agent of the disease is a necrotrophic fungal pathogen, Parastagonospora nodorum, does not fit well into the traditional plant defence theory, but rather to the inverse gene-for-gene model.

Therefore, resistance to SNB is complicated and manipulated by numerous genes/QTL. Interactions occurring between small proteins known as necrotrophic effectors produced by the pathogen and matching dominant susceptible genes in wheat lead to the infection. In this study, RNAseq was used to identify candidate genes.

These genes have been characterised and partially validated using fine mapping of a large Mace x Lancer F2 population. EMS was also deployed to confirm the gene functions. Two candidate genes which interact with a novel P. nodorum toxin, SnTox8 have been identified based on the RNAseq data. Further, fine mapping data from the Mace X Lancer F2 progeny revealed that both genes interact with the toxin and the Gene1 is more significant than the Gene 2.

Finally, a near perfect marker was created but perfect markers are being developed for marker assisted selection tools in wheat disease resistance breeding programs.

The study is on the identification, characterisation, and validation of novel SNB susceptible genes for the first time in Australia for a marker-assisted selection program in wheat. Markers developed from the cloned gene by the end of 2024 could be used for the development of SNB-resistant wheat varieties by breeders.