Progress in breeding wheat for tolerance and resistance to root-lesion nematode (Pratylenchus thornei)

Root-lesion nematode (Pratylenchus thomei) is a serious pathogen of wheat a nd other crops and is estimated to cost the Australian wheat industry $36M per year in lost production. Use of tolerant and resistant wheat cultivars is the most important component of integrated control of this nematode. A t argeted approach has been adopted to develop such cultivars for the norther n grain belt of Australia. Methods are described that have been used succes sfully to screen for tolerance in the field and resistance in the glasshous e. Backcross programs used to incorporate superior tolerance into locally a dapted cultivars have doubled tolerance levels, which translates into doubl e the grain yield on severely infested sites. Resistance from the bread whe at line GS50a backcrossed into locally adapted cultivars has reduced the ne matode multiplication rate more than tenfold in advanced lines. New sources of resistance have been located in Aegilops tauschii, in durum wheat and i n synthetic hexaploid wheats derived from them. Other new sources have been identified in landrace wheats and wheat cultivars from the Middle East and North Africa. A concerted effort is required to exploit these new found re sistances and knowledge to accelerate the production of suitable cultivars for farmers' use.