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From plate to paddock: taking Fusarium crown rot resistance from the lab into the field

Jonathan Powell: CSIRO

<div>Fusarium crown rot, predominantly due to infection by <em>Fusarium pseudograminearum</em>, is a significant constraint on bread wheat, durum and barley production in Australia. Development of varieties with increased resistance leading to yield gain under disease pressure remains the most tractable, long-term solution to this challenge. To this end, four large effect resistance QTL have been identified in bread wheat (on chromosomes 3B, 2D, 5D and 2B) and two in barley (on chromosomes 4H and 1H) respectively and deployed in a breeding program to pyramid and introgress these QTL into elite cultivar backgrounds. Results indicate that combining these QTL effectively decreases the development of disease symptoms and generates lines with yield advantage under disease pressure. Near isogenic lines differing for inclusion of each resistance locus have also been developed to aid the study of the molecular basis of resistance for each of these QTL, facilitate fine-mapping approaches and produce co-segregating markers. Applying RNA-seq approaches to near isogenic lines for the 3B and 4H loci has proven an effective strategy for identifying candidate genes underpinning resistance loci by calling differential gene expression and single nucleotide polymorphisms between resistant and sensitive isolines. Future work will attempt to isolate the underlying causative genes for these QTL and characterise the role these genes play in mediating resistance to fungal diseases.</div>