Development of molecular markers for crown rot resistance in wheat: mapping of QTLs for seedling resistance in a ‘2‐49’ × ‘Janz’ population

Abstract

Crown rot, caused by Fusarium pseudograminearum, is an important disease of wheat in Australia and elsewhere. In order to identify molecular markers associated with partial seedling resistance to this disease, bulked segregant analysis and QTL mapping approaches were undertaken using a population of 145 doubled haploid lines constructed from '2-49' (partially resistant) x 'Janz' (susceptible) parents. Phenotypic data indicated that the trait is quantitatively inherited. The largest QTLs were located on chromosomes 1D and 1A, and explained 21% and 9% of the phenotypic variance, respectively. Using the best markers associated with five QTLs identified by 1

Confirmation of QTL mapping and marker validation for partial seedling resistance to crown rot in wheat line '2-49'

“…2-49 is a line showing partial resistance to crown rot, which resulted from a Gluyas Early × Gala cross in which both parents are partially resistant (Wildermuth and McNamara 1994). In total, 90 DH lines derived from Gluyas Early × Janz were used to confirm the QTL mapping results from Collard et al (2005).…”

“…The original 2-49 × Janz doubled haploid mapping population of 153 doubled haploid (DH) lines is described in Collard et al (2005). 2-49 is a line showing partial resistance to crown rot, which resulted from a Gluyas Early × Gala cross in which both parents are partially resistant (Wildermuth and McNamara 1994).…”

“…DNA extractions, polymerase chain reaction (PCR), and visualisation of PCR products have been described in Collard et al (2005). Twenty-five SSR markers in the chromosomal regions containing QTLs detected in the 2-49 × Janz mapping population (Collard et al 2005) were used to screen 2-49, Gluyas Early, Gala, and Janz in order to infer the origin of resistance QTLs in 2-49.…”

“…Selection for this trait would be greatly assisted by the development of closely linked molecular markers suitable for deployment in a marker assisted selection (MAS) program. To date, there have been only 3 published reports of the identification of markers associated with crown rot resistance (Wallwork et al 2004;Collard et al 2005;Bovill et al 2006).…”

“…In a previous study, we reported the identification of microsatellite single sequence repeat (SSR) markers associated with 2 major QTLs on chromosomes 1D and 1A, and 4 minor QTLs on 2A, 2B, 4B, and 7B for crown rot resistance in a 2-49 × Janz doubled haploid population (Collard et al 2005). 2-49 is an important breeding line that possesses both seedling and adult plant (field) resistance (Wildermuth and McNamara 1994).…”