Fine mapping of adult plant leaf rust resistance gene Lr49 in wheat

Baranwal D*, Bariana H and Bansal U

The University of Sydney Plant Breeding Institute, School of Life and Environmental Sciences, Faculty of Science 107 Cobbitty Road Cobbitty NSW 2570.*Corresponding author: deepak.baranwal@sydney.edu.au.

Sustainable wheat production is continuously affected by several biotic and abiotic stresses. Among biotic stresses, leaf rust caused by Puccinia triticina is considered as a major threat to sustain wheat production across the globe. Adult plant hypersensitive leaf rust resistance (R) genes such as Lr12, Lr22a, Lr22b, Lr35 and Lr49 have been characterised by necrotic flecks or small pustules which check the further proliferation of causing pathogen. Later, Lr49 was characterised as slow rusting resistance gene and is effective against all pre-dominating pathotypes of Australia and India. SNP were identified by aligning the sequences of flow sorted chromosome 4B of parental lines (VL404-Lr49 and WL711-susceptible parent) and converted into KASP markers. KASP markers sunKASP_21 and sunKASP_24, flanked Lr49 proximally and distally, respectively. Current study was planned to develop high-resolution map of Lr49 using 5120 F2 gametes from a cross of VL404/Avocet S to narrow down the physical interval between gene of interest and flanking markers to facilitate map-based cloning. DNA was extracted from leaf tissues from 2560 F2 plants using SDS-extraction method. KASP markers were tested of F2 DNA using real time PCR and LGC genomics protocol. Seventy-two recombinants were identified between flanking markers. These recombinants were screened against PBI leaf rust culture 539 (76-1, 3, (5), 10, 12) to confirm their disease response in F3 generation. Ref seq v 1.0 of Chinese Spring was used to map the flanking markers and these markers mapped in scaffold3450 representing 4Mb region. Markers will be developed to saturate the region.