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| Author(s): |
Danila Montewka Melotto Passarin
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2004-08-05 |
| Advisor: | Helaine Carrer |
| Abstract | |
In the past few years, nucleotide sequencing of chloroplast genome is being used as an efficient tool to study evolution in higher plants. Sequencing of the total chloroplast genome (plastome) from sugarcane (Saccharum officinarum) revealed a 141,182 bp circular double-stranded molecule. This plastome contains a pair of inverted repeat regions (IRA and IRB), separating a small single copy region (SSC) and a large single copy region (LSC). Chloroplast genes have been extensively used to reconstruct the phylogeny in related species. In order to contribute to the amount of information available for phylogenetic reconstruction, it has been analyzed multiple chloroplast regions, including genes and intergenic spacers. The chloroplast DNA (cpDNA) has the feature of being well conserved among the plant species, which makes it appropriate for phylogenetic studies at high taxonomic leveIs. Furthermore, uniparental inheritance presents low impact of intermolecular recombination and helps to simplify theories of ptDNA evolution in most plant taxa. The objective of this work was to contribute to chloroplast evolution studies in several sugarcane species and hybrids by identifying polymorphic regions and phylogenetic signals or hotspots signals that can be useful as phylogenetic markers. For that, other species belonging to Poaceae family, mainly sorghum, maize, rice and wheat have also been comprised in the analyses. The regions selected to this study were: intergenic region between rbcL and petA intergenic region between trnI and trnL; 16SrDNA region and a segment ofthe four cpDNA intersections that link the two inverted repeat regions with the LSC and SSC. These sequences have been amplified by PCR, sequenced and aligned by using the computer programs ClustalW and Phred-Phrap-Consed. The parsirnony analyses were performed by PAUP* version 4.0 program and the phylogenetic trees were designed by TreeView program. The comparisons of cpDNA hotspots have provided useful information on chloroplast evolution and about the mechanisms responsible for divergence among plastomes of these studied species. AIso, it was observed larger identity among sugarcane, sorghum and maize plastomes, which are C4 plants, than between sugarcane and C3 grasses plastomes like rice and wheat, including structural gene organization. (AU) | |