Madina Rasulova Molecular Systematics of Nematodes Page 1

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It is common to find both sexes of sting nematodes in the soil as they reproduce sexually (Fig. 1, B). After mating the female lays eggs in pairs in the soil until the food is available. Juveniles hatch out of eggs after about five days and try to find a root of a plant in order to survive by feeding on it. Juveniles undergo three moults before becoming adults. The total life cycle of Belonolaimus from egg to reproducing adult takes about 18-24 days. While feeding the nematodes inject enzymes into root tissues and suck plant juices out via their stylet (Fig. 1, C) killing the meristematic cells which leads to cessation of growing of root‟s tip (Grosser et al., 2007). This will lead to abnormal formation of roots and consequently result in dramatically decrease of harvest. Due to their significant damage to different crops, measures based on rotation with alfalfa have been applied and were successful, while chemical nematicides could only reduce the number of sting nematodes (Rau, 1963). That is the main reason why these nematodes were of great interest for many scientists (Rau, 1961; Rau, 1963; Abu-Gharbieh et al., 1970; Cherry et al., 1997; Koenning et al., 2006; Han et al., 2006; Grosser et al., 2007; Grosser et al., 2007) and more thoroughly studies, both morphological and molecular, should be conducted in order to understand their evolutionary origination as well as establish the most efficient method of struggle against these economically important pests. MATERIAL AND METHODS A partial nucleotide sequence of unknown Belonolaimus genus was chosen for the project work for further analyzing using different molecular and phylogeny programs. The first step was to find out the species of this genus as well as the type of this given sequence in NCBI GenBank by BLAST of nucleotides (Appendix, Figure 4). According to NCBI GenBank, the studied gene was complete sequence of ITS1 region as well as contained other partial parts in both ends. Two ITS regions of rDNA, which are located between 18S SSU and 5.8S for ITS1 and 5.8S and 28S LSU for ITS2, are particularly well-suited for species and population Madina Rasulova Molecular Systematics of Nematodes Page 4
level analyses because of appreciable nucleotide polymorphism (Campbell et al., 1995; Chilton et al., 1995; Ferris et al., 1995). 18S and 28S genes of rDNA have a characteristic to evolve very slowly and can be used to compare distant taxa where divergence occurred long ago. In comparison, two ITS regions have higher evolution rates and consequently have been used for analysis of relatively recent evolutionary events. Consequently, ITS regions are very important in comparison of closely related species (Subbotin and Moens, 2006) and subspecies and play a role of a genetic marker in taxonomic studies (Cherry et al., 1997). Moreover, rDNA sequences which encode for rRNA (only SSU, 5.8S and LSU are present in mature rRNA after splicing) are present in abundant amount as it is common to find them from hundreds to thousands of tandemly arranged repeats which are separated from each other by intergenic spacer regions (IGS). Thus, several investigations based on molecular data were carried out in order to improve the understanding of Belonolaimus’ systematics, phylogeny and distribution (Cherry et al., 1997; Gozel et al., 2006; Han et al., 2006). For phylogenetic analysis 13 species of nematodes were chosen, 9 out of which were considered as in-group to the previously identified from the given sequence Belonolaimus species and they were selected according to the genus they belong to (all of them were members of the Belonolaimus genus). The rest 3 species were chosen from different families or at least different genera and were considered as out-group. For analyzing the relationship of the chosen species several programs were run which are listed below: BLAST (Basic Local Alignment Search Tool) is used for finding regions of local similarity between given sequence and other sequences available in databases. The principle of the program is based on comparison of nucleotide or protein sequences to sequence databases and calculates the statistical significance of matches. Two of the most important parameters in BLAST are expect value (represents the rate of found hit just by accident, meaning the smaller the E value – the less possibility Madina Rasulova Molecular Systematics of Nematodes Page 5
Page 1 and 2: Madina Rasulova Molecular Systemati
Page 3: very sandy soils and are active whe
Page 7 and 8: constraining, rooting and testing h
Page 9 and 10: 2 DQ672373 Belonolaimus longicaudat
Page 11 and 12: of other species of the same genus
Page 13 and 14: ermudagrass (Poteet) isolates were
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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