Morphological, Cytogenetic and Esterase Isozyme Variation of Root-Knot Nematodes From Ethiopia
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Date
1998-05
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Addis Ababa University
Abstract
Fifty-five populations of root-knot nematodes were established from individual egg masses
collected from different parts of the country. Perineal pattern, stylet length, chromosome number
and esterase isozyme phenotypes of these populations were investigated. Three species were Chromosome number was counted in the germinal zone of the ovary. High intra-specific and
intra-population variability was observed in populations of lvf incognita and lvf ethiopica. In both
species diploid, 36-38 and hypotriploid, 40-46 chromosome numbers were counted. I'd javanica
did not show much variability with a hypotriploid chromosome number of 40-46. Four esterase isozyme phenotypes were identified in the populations of the three species. !vi.
incognita and lvf javallica populations had the I1 and J3 phenotypes, respectively, while !vI
ethiopica populations had two phenotypes, E3 and E2. E3 was found to be species-specific and
potentially useful for diagnosis. Due to its high incidence, lvf ethiopica is considered to be an
important parasite.
identified: I'vieloidogyne incognita (58.2%), lvf javallica (16.4%) and lvf ethiopica (25.4%) based
mainly on perineal pattern and esterase isozyme phenotypes. Populations of 114. incognita.
exhibited extensive variation in perineal pattern, whereas less variability was observed in
populations of lyi. javanica J!Q.Q.lvf ethiopica. Stylet length of populations of !vI javanica and !vi.
ethiopica obtained from enset was found to be significantly larger (P = 0.05) than the other
populations. This is thought to be a possible form of an adaptation.
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Biology