Molekulske osnove somaklonske variabilnosti in njena uporabnost za žlahtnjenje rastlin

Petrovčič, Brina (author), Murovec, Jana (mentor)

Somaklonska variabilnost je variabilnost med rastlinami, regeneriranimi v tkivnih kulturah, zaradi genetskih in epigenetskih sprememb v genomu. Analiza molekularnega ozadja tega pojava je nujna za razumevanje mehanizmov njenega nastanka. Vzroki za nastanek somaklonov so lahko izražanje že sicer prisotnih mutacij in ostalih genetskih ter epigenetskih sprememb ter indukcija sprememb zaradi gojenja in vitro. Primer inducirane spremembe, ki se zgodi na nivoju genov in genoma, je demetilacija. Demetilacija je proces, ki med drugim sproži aktivacijo prej utišanih delov v genomu, imenovanih transpozoni. Transpozoni ali transpozonski elementi so sekvence v DNA, ki lahko spremenijo svojo lokacijo v genomu. S tem spremenijo strukturo kromosomov in vplivajo na izražanje genov. Na primeru riža so raziskovalci ugotovili, da je več kot 50% citozina transpozonov metiliranega, kar jih vzdržuje v utišanem stanju. Poleg tega so dokazali, da se je med tkivno kulturo izmed 43 prisotnih transpozonov aktiviral in premestil le retrotranspozon Tos17. Regenerirane rastline so vsebovale še številne polimorfizme posameznih nukleotidov (ang. Single nucleotide polymorphism, SNP), insercije in delecije. Ker je še veliko drugih mehanizmov, ki povzročajo somaklonsko variabilnost, nepojasnjenih, so za raziskave sprememb najbolj primerne metode nove generacije sekvenciranja (ang. next generation sequencing, NGS). Tehnologije nove generacije sekvenciranja ali NGS omogočajo hitro in učinkovito sekvenciranje celotnih genomov rastlin in se pogosto uporabljajo tudi za ugotavljanje vzrokov somaklonske variabilnosti. Somaklonska variabilnost se lahko uporablja za žlahtnjenje rastlin, saj so genetske spremembe ključne za izboljševanje lastnosti rastlin. Rastlinske tkivne kulture omogočajo hitrejši način žlahtnjenja rastlin na različne načine. Eden izmed teh je somaklonska variabilnost, ki je podobna spremembam, ki nastanejo z mutageni kemijske ali fizikalne narave. Žlahtnitelji lahko z njo pridobijo rastline, tolerantne na biotski in abiotski stres, kot je na primer suša.

• Language: Slovenian
• Keywords: somaklonska variabilnost, transpozoni, žlahtnjenje, biotski stres, abiotski stres
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Year: 2024
• PID: 20.500.12556/RUL-155984
• COBISS.SI-ID: 194260227
• Publication date in RUL: 26.04.2024

Secondary language

• Language: English
• Title: Molecular mechanisms of somaclonal variation and its use in plant breeding

Abstract

Somaclonal variation is variability of plants, regenerated from tissue culture, that happens because of genetic and epigenetic changes in the genome. Analysis of the molecular background of this variability is crucial for understanding the mechanisms of its occurrence. Reasons for the occurrence of somaclones can be expression of the already present mutations and other genetic and epigenetic changes and the induction of changes due to growing plants in vitro. An example for induced changes is demethylation. Demethylation is a process that activates silenced parts of the genome, called transposons. Transposons or transposable elements are DNA sequences that can change the location in the genome. This transfer can change chromosomal structure and gene expression. Scientists had discovered that more than 50% of cytosine of rice transposons is methylated which keeps them in the silenced state. Besides that, they had proved that during tissue culture only retrotransposon Tos17 transfers of all 43 transposons. There were also present many single nucleotide polymorphisms or SNP, insertions and deletions in the regenerants. Because somaclonal variation mechanisms are not entirely understood, most suitable methods for research are next generation sequencing or NGS, which enable fast and effective sequencing of plants’ whole genomes. Somaclonal variation could be used for plant breeding due to genetic changes being pivotal for quality improvement. Tissue culture enables faster breeding techniques, one of them being somaclonal variation which is similar to changes that are caused by chemical or physical mutagens. That way breeders attain tolerant plants to biotic and abiotic stress, for example drought.

• Keywords: somaclonal variation, transposons, plant breeding, biotic stress, abiotic stress