Oral Presentation Science Protecting Plant Health 2017

Selecting wheat cultivars that combine root-lesion nematode (Pratylenchus thornei and P. neglectus) resistance and P. thornei tolerance. (4068)

Jason Sheedy 1 , Neil Robinson 1 , Jing Lin 1 , Roslyn Reen 1 , Timothy Clewett 1 , John Thompson 1
  1. University of Southern Queensland, Toowoomba, QUEENSLAND, Australia

Root-lesion nematodes (RLN; Pratylenchus thornei and P. neglectus) are widely distributed in Australian grain producing regions, can reduce the yield of intolerant wheat cultivars by >50% and cost the industry ~$123 M/yr. Development of commercial varieties combining tolerance and resistance to manage RLN depends on pre-breeding projects producing suitable parental cultivars. To this end, BC1F2 to BC1F4 breeding populations derived from RLN-resistant CPI133872/Janz double haploids crossed with the P. thornei tolerant wheat cvs. EGA Wylie and/or EGA Gregory were screened in the glasshouse for P. thornei and P. neglectus resistance simultaneously using mixed species inoculum or in the field for P. thornei tolerance. Each trial was designed in blocks that allowed comparison between at least 256 segregating individuals and replicated check cultivars. In each generation, individuals identified as resistant or tolerant were progressed to the next generation of selection. By the BC1F5 generation, 48 putatively resistant and tolerant cultivars had been identified. These cultivars were characterised for P. thornei and P. neglectus resistance and P. thornei tolerance in separate replicated trials for two years. Resistance was recovered in 42 (88%) cultivars for P. thornei, seven (15%) for P. neglectus and moderate tolerance in 12 (25%) for P. thornei. Ten (21%) cultivars combined P. thornei resistance and tolerance with one (2%) of these cultivars also combining P. neglectus resistance. This research has shown that RLN resistance and tolerance selected during segregating generations can be carried through until genetic homozygosity is achieved in later generations. This is likely due to the polygenic and additive mode of inheritance of these traits. Providing parental cultivars with resistance and tolerance to both these important RLN species is an attractive proposition for plant breeders. Furthermore, development of commercial cultivars that effectively manage both single species or mixed species infestations will minimise yield loses caused by RLN.