Development of methods for screening sugarcane and Erianthus germplasm for resistance to plant-parasitic nematodes.

SINCE PLANT-parasitic nematodes are a major constraint to sugarcane production in Australia and previous research has shown that Erianthus arundinaceus has resistance to both root-knot nematode (Meloidogyne javanica) and root lesion nematode (Pratylenchus zeae), introgressions of sugarcane with this and other wild species are being screened in the glasshouse for resistance to these nematode pests. This paper discusses work that was undertaken to optimise high throughput screening methods of introgression sugar cane clones. In the case of root-knot nematode screening: sandy soils were found to be the best potting medium for growing sugar cane plants, a bleach method of retrieving eggs from roots proved to be the best nematode extraction method and a simple gall rating index produced results that were highly correlated with nematode counts. In the process of undertaking these experiments, previous findings that some Erianthus clones have a high level of resistance to root-knot nematode were confirmed. In the case of root lesion nematode screening; nematode population densities reached a maximum about 11 weeks after pots were inoculated and final nematode population densities were highest in a commercial potting medium. A tray extraction method proved to be the best method of retrieving the root lesion nematodes from roots and soil, but only about 25% of the nematodes were recovered with a 3-day extraction period. On the basis of these results, methods suitable for screening large numbers of sugarcane clones for nematode resistance have been established.