Madina Rasulova Molecular Systematics of Nematodes Page 1

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B.longicaudatus DQ672384 occurs in different places in different trees. But, nevertheless, MP and ML trees have exactly the same topology. DISCUSSION In current observation 3 such species as B.euthychilus, B.gracilis and Belonolaimus sp. were chosen in order to find out their relationship with the species of our choice – B.longicaudatus (DQ494797). Among 13 isolates 10 were identified as in-group consisting of 6 B. longicaudatus species only and 2 B.gracilis, 1 B.euthychilus, and 1 Belonolaimus sp. “Manteo North Carolina”; while the rest were outgroup species comprised of Ditylenchus dispaci, Hoplolaimus columbus, and Tylenchorhynchus annulatus. According to Rau (1963), B.longicaudatus differs from B.gracilis with such morphological characteristics as having sclerotized plates in the vagina, an elongated rather than spherical metacorpus and a hemispherical rather than convex-conoid tail shape. Despite the fact that B.euthychilus looks like B.gracilis, it exhibits sexual dimorphism (males with degenerated stylet and pharynx) and does not possess a constriction between the labial region and the body. Since ITS regions are important in analysis of different populations of the same species, a number of investigations were based on ITS1 and ITS2 parts for studying different populations of the genus Belonolaimus. Thereby, Cherry et al. (1997) indicated that B. longicaudatus isolates were relatively recent introduced into the state of California in comparison to Florida and South Carolina. According to morphological data, the research of Han et al. (2006) showed that females of the isolates from corn (Scotland County) and citrus (Lake Alfred) fields possess teardrop or kidney-shaped stylet, whereas in isolates from cotton field (Tifton) is typically oval. The vaginal pieces of isolates from citrus field (Lake Alfred) were the most prominent and clearly recognized among all isolates, but of those found in corn field (Scotland County) were weakly developed and not clearly recognized. Based on molecular data it was possible to conclude that all phylogenetic trees supported that the corn (Columbus, South Carolina), Madina Rasulova Molecular Systematics of Nematodes Page 12
ermudagrass (Poteet) isolates were clearly different from the bermudagrass (Gainesville), potato (Hastings), citrus (Lake Alfred), cotton (Tifton) and corn (Scotland County) isolates. Gozel et al. (2006) studied the D2-D3 and ITS regions of rDNA. The most striking point of her phylogenetic analysis is that none of the three nominal species (B. longicaudatus, B. euthychilus, and B. gracilis) are monophyletic. The studies made it possible to identify suites of morphological/morphometric character states that discriminated between the molecular-derived clades of B.longicaudatus. According to the tree, relationships between B. euthychilus BePi1 and B. gracilis BgPi2 were unresolved (the presence or absence of an offset head; the population BgPi2 was identified as B. gracilis, but according to the gene sequence was much closer to B. euthychilus. However, the character appeared to be intermediate between the two species, being somewhat less distinctly offset than in B. gracilis). The ratio „stylet length:tail length‟ has been used like a morphometric character that distinguishes B. longicaudatus from both other species. Stylets were shorter than tails (ratio < 1.0) in 83-100% of B. longicaudatus specimens from 15 populations (from Florida to New Jersey) and stylets were longer than tails (ratio > 1.0) in all observed specimens of B. gracilis and B. euthychilus (Rau, 1961; Rau, 1963). On the other hand, five B. longicaudatus populations (citrus orchards in Polk County, sugarcane in Martin County) had stylets that were on average longer than tails (Duncan et al., 1999). In fact, the ratios are intermediate between those reported by Rau (1961) for B. longicaudatus and B. gracilis. Besides, the stylet:tail ratios for B. euthychilus are very similar to those of B. gracilis. Therefore, it is possible to discriminate B. gracilis and B. euthychilus from B. longicaudatus. It is possible to conclude that B. longicaudatus populations have a more recent evolution with a ratio > 1.0 differ in ITS region by no more than two base pairs, while most B. longicaudatus populations with a ratio < 1.0 have a wide variation in both D2-D3 and ITS nucleotide sequences (Gozel et al., 2006). Like in our research, comparisons of the MP and ML trees revealed no significant differences based on the topological features. Madina Rasulova Molecular Systematics of Nematodes Page 13
Page 1 and 2: Madina Rasulova Molecular Systemati
Page 3 and 4: very sandy soils and are active whe
Page 5 and 6: level analyses because of appreciab
Page 7 and 8: constraining, rooting and testing h
Page 9 and 10: 2 DQ672373 Belonolaimus longicaudat
Page 11: of other species of the same genus
Page 15 and 16: outside of Florida are reproductive
Page 17 and 18: Han H-R., Jeyaprakash A., Weingarth
Page 19 and 20: APPENDIX Figure 4. Results of BLAST
Page 21 and 22: Figure 7. NJ, MP and ML trees with
Page 23 and 24: Figure 9. Phylogenetic tree MP. Max
Page 25: Figure 11. Phylogenetic tree MrB. B

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