| Ascribing function to the genes in a species is one of the most instructive ways to learn about the underlying mechanisms an organism employs to overcome its specific environmental challenges. Following the genomic sequencing and assembly of the root-knot nematode Meloidogyne hapla, a gene set was constructed to provide a foundation for understanding the specific means by which plant parasitism is achieved. The utilization of manual computational gene finding for a subset of the genome, paired with automated gene-finding programs enhanced the accuracy of the resulting gene set. Broad trends in the genome-lifestyle relationship can be uncovered by analyzing groups of genes with similar structures. Through the comparison of the G-Protein Coupled Receptor, Nuclear Hormone Receptor, and collagen gene families found in the model free-living bacterivore C. elegans to M. hapla , a clearer relationship of gene structure and function to nematode lifestyle mode emerges. For all three families, a C. elegans expansion and/or an M. hapla reduction was observed, emphasizing the breadth in ability (through larger gene families) required for a free-living lifestyle and the efficient dependency on host resources (through more compact gene families) needed for a parasitic lifestyle. Prior discoveries of horizontal gene transfer and protein mimicry in nematodes inspired a broad screen for M. hapla-encoded plant peptide hormones. This analysis resulted in the identification of a putative M. hapla Rapid Alkalinization Factor (RALF) plant hormone mimic, which presumably plays a key role in host development events critical for the survival of the plant parasite. |
