Expressed sequence tag analysis generated from a normalized full-length cDNA library of the root-knot nematode (Meloidogyne incognita)

Root-knot nematodes are obligatory sedentary endoparasites that require a plant host to complete their life cycle. To understand the functions of Meloidogyne incognita nematode genes transcribed from eggs and second-stage juveniles (J2), we have constructed a normalized full-length M. incognita cDNA library and analyzed the ESTs using Pendant-Pro Sequence Analysis Suite. The 5,832 M. incognita ESTs formed 3,263 clusters and 2,241 singletons. The sequences ranged from 51 to 1,740 base pairs, and their average size was 699 base pairs. The protein length of M. incognita ESTs ranged from 150 to 299 amino acids. Forty contigs of predicted proteins that were grouped by BLASTP identity values had significant homology to the genes expressed in their organelle structures (cuticle, epidermis, extracellular matrix and muscle). Using the gomerger method of contigs, we could functionally assign GO terms to 2,147 (53.4%) of 4,024 contigs. Following the E. C. numbers method using UniProt database hits, we could functionally classify E. C. numbers to 288 (7.2%) of 4024 contigs. Also, the taxonomy was classified to 2,329 (57.9%) of 4,024 contigs. We could predict transmembrane regions of 4,024 clusters using the TMpred algorithm. Of the 4,024 contigs with transmembrane regions, 1,457 (36.2%) were assigned more than one domain, and 2,567 (63.8%) could not be assigned a transmembrane domain. The M. incognita ESTs will provide a foundation for developing novel target genes for parasite control and contribute to accelerating the research of biologically-related species.