The root lesion nematode (RLN) Pratylenchus neglectus is a root damaging pathogen with an extremely wide host range including all major legume and cereal crops and is common in respective agricultural zones. Lack of resistance or tolerance in crop species causes considerable yield losses that can be worsened in low rainfall conditions as the affected root system is unable to use water efficiently. Although showing moderate resistance to RLN, annual medics are intolerant to the pathogen and can suffer severe losses in biomass and seed production, as much as 20% in heavily infested paddocks. Currently, considerable investments are being made into the search for sources of RLN resistance and tolerance in wheat. As a rotation crop with wheat, tolerance to RLN becomes even more important as tolerance in future wheat varieties will lead to an increase or at least maintenance of the nematode population in the field. RLN field assays show that each additional nematode per gram soil translates into an additional 1% yield loss in annual medics. In SARDI, a germplasm screen has already led to the identification of a RLN tolerant strand medic line (RH1). Inheritance of the tolerance has been shown and a population has been established, which is proposed to be used for molecular marker development. Markers will be developed to select the notoriously difficult and expensive tolerance phenotype to facilitate introgression into breeding lines and are particularly important where the trait is being combined with other valuable traits in more complex crosses currently in development.
Minister for Primary Industries and Regional Development acting through the South Australian Research and Development Institute
Major objective is the development of molecular markers linked to root lesion nematode tolerance in strand medics (Medicago littoralis). The first step towards achieving this objective is to develop a genetic map of the existent F6 population Herald/RH1 that will be used for the identification of the regions in the genome that are responsible for the observed RLN tolerance. Identification of these genomic regions allows the development of molecular markers utilising the sequenced genome of the closely related species M. truncatula. These markers will then be used to introgress the most significant tolerance loci from tolerant line RH1 into elite varieties to make them more productive in the presence of RLN. If time allows and for widest possible utilisation of project outputs, we will test the new markers also on RLN tolerant lucerne (Medicago sativa) lines that have recently been identified in SARDI’s lucerne breeding program (Ross Ballard and Alan Humphries).
Project Start Date
Tuesday, June 15, 2010
Project Completion Date
Tuesday, October 15, 2013
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