title: Genetic structure of Xiphinema pachtaicum and X. index populations based on mitochondrial DNA variation.
abstract: The dagger nematodes Xiphinema pachtaicum and X. index are two of the most widespread and frequently occurring Xiphinema spp. co-infesting vineyards and other crops and natural habitats worldwide. Sexual reproduction is rare in these species. The primary objective of this study was to determine the genetic structure of X. pachtaicum and X. index populations using eight and seven populations, respectively, from different "wine of denomination of origin (D.O.) zones" in Spain and Sardinia (Italy), by studying mitochondrial (cytochrome oxidase c subunit 1 or COI) and nuclear (D2-D3 expansion segments of 28S rDNA) markers. Both Xiphinema spp. showed low intraspecific divergence among COI sequences, ranging from 0.2% (1 base substitution) to 2.3% (10 substitutions) in X. pachtaicum and from 0.2% (1 base substitution) to 0.4% (2 substitutions) in X. index. Population genetic structure was strong for both species. Nevertheless, molecular differences among grapevine-growing areas were not significant, and intrapopulation diversity was very low. It is hypothesized that this genetic homogeneity in the nematode populations reflects their predominant parthenogenetic reproduction mode and low dispersal abilities. Our results also show that X. pachtaicum populations in Spain have possibly been established from two different populations of origin. Results also demonstrated that the two DNA regions studied are suitable diagnostic markers for X. index and X. pachtaicum.
authors.affiliation: Instituto de Agricultura Sostenible, Cordoba, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Gutiérrez-Gutiérrez
authors.forename: Pablo
authors.initials: P
authors.lastname: Castillo
authors.forename: Carolina
authors.initials: C
authors.lastname: Cantalapiedra-Navarrete
authors.forename: Blanca B
authors.initials: BB
authors.lastname: Landa
authors.forename: Sofie
authors.initials: S
authors.lastname: Derycke
authors.forename: Juan E
authors.initials: JE
authors.lastname: Palomares-Rius
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D005819:Genetic Markers / Q000235:genetics; D040342:Genetic Structures / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes; D007558:Italy; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009348:Nematoda / Q000235:genetics* / Q000302:isolation & purification; D010802:Phylogeny; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013030:Spain; D027843:Vitis / Q000469:parasitology*
chemical_list: D018509:DNA, Helminth; D004272:DNA, Mitochondrial; D005819:Genetic Markers; D012339:RNA, Ribosomal, 28S; D003576:Electron Transport Complex IV