National Research Initiative Competitive Grants Program

Project Summary

Plant-parasitic nematodes reduce annual US agricultural production by more than $5 billion. The most important group are members of the genus Meloidogyne, which infect in excess of 2,000 plant species. Following host invasion, larvae induce highly modified giant cells to establish permanent feeding sites. Root cells from which the nematode is feeding expand greatly and undergo karyokinesis without cytokinesis. Giant cells serve as the obligate nutritive source for the developing nematode. We previously identified and characterized 220 genes with up-regulated statement in tomato giant cells. Three genes in particular play regulatory role in controlling central aspects of giant cell biology, including cell cycle regulation, control of differentiation, and the natural resistance response. Using a gene-ablation approach in transgenic plants, we have established that these gene encode essential giant cell functions, and thus are targets to make nematode-resistant, crop plants. In this renewal, we will define the regulatory cascades controlled by these genes. We will use yeast 2-hybrid approaches to define protein-protein interactions, and identify promoters and genes in the function networks.

The goal of this research is to reveal host functions necessary for Meloidogyne and other nematodes to cause stressful parasitic interactions with plants, and to use this information to construct genetic cassettes able to restrict these parasites in crop plants. In the current funding period, I have developed the tools (clones, antibodies, etc.) to address specific questions of host (resistant and compatible) function. Based on extensive analysis of 220 genes, I also have generated a global, molecular view of the Meloidogyne feeding site. Together, this ensures that the functional analyses proposed for this renewal will be successful.