Poster Presentation Science Protecting Plant Health 2017

Delivering novel genetic solutions to control yellow spot in wheat (#131)

Eric Dinglasan 1 , Dharmendra Singh 1 , Ian Godwin 2 , Huyen Phan Phan 3 , Pao Theen See 3 , Caroline Moffat 3 , Kar-Chun Tan 3 , Lee Hickey 1
  1. Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia
  2. School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD, Australia
  3. Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102

Yellow spot or tan spot is a serious disease of wheat crops globally. It is caused by Pyrenophora tritici-repentis (Ptr) which produces three major necrotrophic effectors (i.e. ToxA, ToxB, ToxC) that interact with specific sensitivity genes in wheat (i.e. Tsn1, Tsc2, Tsc1, respectively). In Australia, Ptr Race 1 (ToxA and ToxC) is widespread infecting the majority of modern wheat cultivars, in which Tsn1 is prevalent. The absence of effector-host-gene interactions is correlated with resistance, but still, there is considerable phenotypic variation in response to Ptr. This implies the presence of other genetic factors that may contribute to quantitative forms of resistance, similar to other cereal-pathosystems. Here, we search for novel sources of genetic resistance to Ptr Race 1 using 300 diverse wheat accessions originally sourced from the Vavilov Institute. We report a rapid phenotyping protocol utilising accelerated growth conditions (constant light and controlled temperature), suitable for evaluating adult plant response to Ptr. The rapid phenotyping technique, ToxA bioassay, and field assessments were performed to screen the diverse wheat accessions. Using DArT-seq DNA markers, genome-wide association studies identified novel genomic regions conferring resistance. Interestingly, some accessions carried Tsn1, yet displayed a high degree of resistance to ToxA-producing races. To further examine these genetic factors, a recombinant inbred line (RIL) mapping population was generated, which was fixed for Tsn1, yet segregating for resistance. The RIL was genotyped using DArT-seq and evaluated by Ptr inoculations and ToxA bioassay. Further analysis of this key population will hopefully improve our understanding of the genetic mechanisms that may be harnessed in the presence of Tsn1. Thus, in addition to removing major sensitivity loci that are widespread in elite wheat germplasm, we propose manipulation of host loci that are dominant over Tsn1 resistance could offer an alternative genetic solution for control of yellow spot disease.