International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

Novel sources of resistance to septoria nodorum blotch in the Vavilov wheat collection identified by GWAS


Huyen Phan
Curtin University

Kasia Rybak
Curtin University

Stefania Bertazzoni
Curtin University

Eiko Furuki
Curtin University

Eric Dinglasan
The University of Queensland

Lee Hickey
The University of Queensland

Richard Oliver
Curtin University

Kar-Chun Tan*
Curtin University


Oral Presentation
Host Genetics and Resistance Breeding

Moore Auditorium, UCD O'Brien centre for Science
24 May 2019, 11:00

View this abstract online by visting isclb2019.com/see/ABS97683

The fungus Parastagonospora nodorum causes septoria nodorum blotch of wheat. This disease is the outcome of multiple fungal necrotrophic effector-host sensitivity gene interactions that include ToxA-Tsn1, Tox1-Snn1 and Tox3-Snn3. Previous work demonstrated that the triple-knockout strain P. nodorum toxa13 maintained the ability to infect most modern bread wheat cultivars as effectively as the wildtype SN15. This suggests evidence of uncharacterised effector-host dominant susceptibility gene interactions or the lack of a resistance mechanism. To search for additional sensitivity genes, as well as putative resistance genes, a diversity panel of 295 historic wheat accessions from the N. I. Vavilov Institute of Plant Genetic Resources in Russia were chosen. This germplasm collection comprises of genetically diverse landraces and historic breeding lines registered from 1920 to 1990. Both P. nodorum SN15 and toxa13 were assayed on the Vavilov panel. SN15 was more virulent than toxa13. The subset of wheat lines insensitive to all three effectors showed significantly lower levels of disease when infected with SN15. However, the subset were no less susceptible to the toxa13 as the rest of the Vavilov collection. GWAS using SN15 assay detected quantitative trait loci (QTL) on chromosomes 1BS (Snn1), 2DS, 5AS, 5BS (Snn3), 3AL, 4AL, 4BS and 7AS. For toxa13 infection, a similar QTL was detected on 5AS, plus two additional QTL on 2DL and 7DL. Through historic temporal analysis, this study further revealed that plant breeders inadvertently selected for effector insensitivity from 1940 onwards. Outcomes from this study will help to identify accessions for development of bi-parental mapping populations to characterise resistance-associated alleles for subsequent introgression into modern bread wheat.