Portal de Periódicos da CAPES

Genome size of plant-parasitic nematodes

2007; Brill; Volume: 9; Issue: 3 Linguagem: Inglês

10.1163/156854107781352089

1568-5411

Stéphanie Leroy, Salah Bouamer, Sergé Morand, Mireille Fargette,

Parasite Biology and Host Interactions

tion. Representative specimens from the samples of each species were handpicked, fixed in hot 4% formaldehyde, transferred to anhydrous glycerol and mounted on Cobb slides to confirm identification. Morphology and morphometrics of specimens were compared to information in the literature and/or direct observations on reference material in collections. Haploid genome sizes and standard deviations are shown in Table 1. For seven taxa, standard deviations were less than 10% of the corresponding genome size; for two, they were between 15 and 20% and about 40% for Hemicycliophora conida. With the exception of Pratylenchus coffeae (very small genome and small standard deviation), the lack of precision in measurements tended to increase with decreasing genome size, implying that the technical limitation of the flow cytometry approach for determining genome size is reached with some genomes of plantparasitic nematodes. However, it was possible to provide, with confidence, the records for the genome sizes of seven plant-parasitic nematodes and, with adequate confidence, for two more. With this level of accuracy, it was also possible to confirm significant differences in sizes between different genera within the same family and subfamily. For example, the Nagelus obscurus genome size was found to be twice as large as that of Neodolichorhynchus lamelliferus, and of T. graciliformis (both belong to the same family as N. obscurus), and of Merlinius brevidens (same subfamily as N. obscurus). Polyploidisation events as mentioned by Gregory (2005) between congeneric species may explain such differences between closely related genera.