Oral Presentation Science Protecting Plant Health 2017

Deciphering the molecular mechanisms of Lr34-mediated disease resistance in wheat (4242)

Dharmendra Singh 1 , Adnan Riaz 1 , Jonathan Powell 2 , Timothy Fitzgerald 2 , Kemal Kazan 2 , Neena Mitter 2 , Evans Lagudah 3 , Lee Hickey 1
  1. The University of Queensland, Brisbane, QUEENSLAND, Australia
  2. Commonwealth Scientific and Industrial Research Organization (CSIRO) Agriculture, St Lucia, QLD, Australia , Brisbane, Queensland, Australia
  3. Commonwealth Scientific and Industrial Research Organization (CSIRO) Agriculture, Canberra, ACT, Australia

The Lr34/Yr18/Sr57/Pm38/Ltn1 multi-resistance locus has been effective and deployed in wheat cultivars for more than 100 years. The durability and pleiotropic nature makes Lr34 a unique and highly valuable resource for rust resistance breeding. Despite its functional annotation as ABC transporter, the mode of action is unknown. Considering this, we aimed to decipher molecular factors and signalling components using RNA-seq of Chara resistant (Lr34) and Chara heavy ion irradiation (HII) mutant susceptible (Lr34) wheat lines. The screening of Chara and Chara HII lines with Lr34 gene specific markers confirmed the integrity of Lr34 in both lines, however, phenotyping confirmed rust susceptibility in Chara HII lines. Plants were grown under controlled conditions and infected with Puccinia triticina pathotype 76-1,3,5,7,9,10,12,13+Lr37 at the fully expanded flag leaf stage. Flag leaves were sampled at 0, 24, 48, 72, 96 and 168 hours post inoculation (hpi) from mock and infected plants. Based on real-time PCR analysis of basal defence genes and the Lr34 gene, we selected 72 hpi for RNA-seq with four biological replicates per condition. The samples were sequenced on Illumina Hiseq 4000 at Beijing Genomics Institute, China. A total of 9.0 Gb sequences (2.25 Gb/ library) from 16 libraries for four conditions were obtained. Differential expression analysis was performed using the ‘Tuxedo’ analysis pipeline with standard parameters. Analysis revealed differential expression of key defense related genes, transcription factors and disease response associated proteins involved in molecular basis of Lr34 mediated resistance. The validation of genetic components confirm their role in the activation and regulation of Lr34 gene and resistance pathway. This insight may improve our ability to harness Lr34 in wheat and other crops using genetic engineering approaches.