Isolation of the rDNA internal transcribed spacer region in five species of parasitic nematodes infesting banana plants in Peninsular Malaysia.

Z., Mohamed, and N., Mohd Zain, S. and A., Sayed Abdul Rahman, S. (2006) Isolation of the rDNA internal transcribed spacer region in five species of parasitic nematodes infesting banana plants in Peninsular Malaysia. UNSPECIFIED.

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Abstract

<p><font face="Arial">Nematode infestation on bananas has been identified as the key contributing factor to increased crop losses worldwide. The reduction of crop yield is sequential to poor plant development triggered by nematode infesting the root and/or corm tissues of the host plants. Subsequently, the mechanical and physiological function of the root system is reduced and therefore, the plant has to succumb to nutrient insufficiency that consequently affects plant growth and development. Different nematode species will manifest different pathogenicity levels to the hosts. Therefore, knowledge of genetic diversity of the parasites for the development of an effective resistance breeding program for the hosts is crucial.<br /> &nbsp;Sequence comparison from nuclear ribosomal DNA (rDNA) has been evaluated as a means to clarify phylogenetic relationships among populations and species of numerous organisms including nematodes. As a result of a concerted pattern of evolution demonstrated by the multi-copy of ribosomal RNA genes of many eukaryotic organisms, the majority of the repeat copies within a genome of a species are of a single sequence. However, interspecific difference in sequences was perceived to be more pronounced in spacer regions that lie between the genes in the tandem rDNA gene clusters .<br /> &nbsp;Nematode rDNA is comprised of multiple repeats of three ribosomal genes interspersed between spacer regions of DNA. The spacer regions, which were also termed as the Internal Transcribed Spacer (ITS) regions, could provide a reliable tool of resolving phylogenetic relationship between closely related nematode taxa. By manipulating the nature of the rDNA structure, this study aims to investigate intraspecific and interspecific genetic variations demonstrated by the nematode isolates, thus, exploring the genetic diversity of the parasites.<br /> &nbsp;Two sets of universal rDNA primers were used to compare the ITS regions of five nematode species isolated namely Radopholus similis, Meloidogyne incognita, Helicotylenchus dihystera, Helicotylenchus multicinctus and Hoplolaimus spp. Highly conserved sequences found in the rDNA genes were manipulated in designing the universal primers that will amplify the orthologous fragments from all nematode taxa with similar priming sites. Both pairs of primers used, targeted the 18S and 28S genes in order to amplify the ITS1, 5.8S and ITS 2 regions. The first primer pair was applicable&nbsp; for the amplification of the ITS regions of all plant-parasitic nematodes as described by Fallas et al., 1996 and Kaplan et al., 2000 while the second primer pair on the other hand was used to amplify the ITS regions from Meloidogyne incognita. Amplification of the ITS regions was carried out by PCR. Amplified products were then isolated and subjected to cloning. Successfully cloned fragments were subsequently sent for sequencing.</font></p> <p><font face="Arial"></font>&nbsp;</p>

Item Type: Other
Uncontrolled Keywords: Isolation of the rDNA internal transcribed spacer region in five species of parasitic nematodes
Subjects: Q Science
Depositing User: MR. ADNAN YAHYA
Date Deposited: 14 Jul 2012
Last Modified: 14 Jul 2012
URI: http://repository.um.edu.my/id/eprint/90358

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