Chromosome set doubling and DNA methylation as triggers of phenotypic variability in Eucalyptus sp.

• Ano de defesa: 2020
• Autor(a) principal: Silva, Alex Junior da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Eucalipto; Poliploidia; Epigenética; Florestas - Melhoramento genético; Biotecnologia; Melhoramento Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/28770

Genomic changes as chromosome set doubling and DNA methylation patterns have a profound significance in ecological and evolutionary aspects, shaping plants to different environments and adverse conditions. Within this context, induced changes in whole genome by duplication or manipulation of DNA methylation patters, could create advantageous phenotypes, inheritable and stable, and therefore, passive of selection in breeding programs. In this sense, we evaluated the effect of chromosome set doubling in Eucalyptus benthamii trees in the context of secondary metabolism, and whole DNA demethylation in germinated seeds of Eucalyptus urograndis during in vitro organogenesis. Autotetraploid trees of E. benthamii produced 1,8-cineole, limonene, α-terpineol, and α-terpynil acetate which in contrast were absent in diploids, and yielding of essential oils were not correlated to the ploidy level. Diploid essential oils have twice more larvicidal effect against Aedes aegyptii larvae than autotetraploids. Essential oils from both ploidy levels had no cytogenotoxic effect in meristematic roots of Lactuca sativa. Besides the ploidy level alterations, epigenetic changes in the global DNA methylation levels may promote stable phenotypes of forest interest. In E. urograndis plantlets, using 5-Azacytidine it was possible to reduce 5-methyl cytosine levels in whole plant (roots, hypocotyls, cotyledons and leaves). Treatments with this demethylating agent promoted an increase of 65% in rooting formation without plant growth regulators. Subsequent DNA demethylation through organogenesis promoted a reduction of 50% in global DNA methylation of regenerated plants. Chromosome set doubling and DNA demethylation are powerful tools to modify phenotypic diversity in short-term, and in long-term these changes can be more explored aiming desirable traits in forest breeding. Keywords: Polyploidy. Epigenetic. Forest breeding. Biotechnology. Eucalypts.