Scientists get to the root of crop attack

WHEN the United States and Europe ban soil fumigation chemicals and toxic nematocides in 2004-05, farmers and horticulturists will be relying on scientists like Dr Zhaohui Wang to find new ways to fight root-knot nematodes that ravage up to 2000 crop species.

Dr Wang is based at the WA State Agricultural Biotechnology Centre at Murdoch University, where he is investigating the changes in gene expression in host plants after they have been infected with the nematode parasites.

He hopes this work will lead to the discovery of genes that can be targeted to help develop a range of nematode-resistant crops.

“The group of root-knot nematodes in this study attack plants by invading their roots and feeding from modified root cells,” Dr Wang said.

“The plants become mineral deficient, suffer from water stress and become vulnerable to attack by other pathogens, which adds to farmers’ woes. Damage by nematodes to crops is estimated to cost agriculture about A$135 billion per year worldwide.”

Dr Wang and his PhD student Angela Hollams are searching for target genes whose expression could be modified to generate plant resistance to the nematode pathogens - they realise that they have a large task ahead.

“Natural nematode resistance genes in host plants are effective only against specific races of the endoparasitic nematodes and a combination of different strategies or target genes may have to be used to engineer plant resistance,” Dr Wang said.

This work is part of ongoing studies of the Plant Biotechnology Research Group in the SABC on the molecular basis of hostpathogen interactions of endoparasitic nematodes, and is funded by an Australian Research Council Discovery grant.