Caracterização de trigo sintético à giberela (Gibberella zeae) (Schw.) Petch, índice meiótico e diversidade genética.

Orientadora: Carolina Cardoso Deuner; Coorientadora: Sandra Patussi Brammer

Genetic stability in synthetic wheat accessions: cytogenetic evaluation as a support in breeding programs.

ABSTRACT: Synthetic wheat is developed by crossing tetraploid species ( Triticum turgidum , AABB) with a diploid species ( Aegilops tauschii , DD), followed by chromosome duplication through the use of colchicine to restore the resultant sterile hybrid to a fertile hexaploid plant. The main importance of producing synthetically improved wheat is to increase their genetic variability and to incorporate genes that code for resistance to biotic and abiotic stressors. This study aimed to evaluate the presence of micronuclei (MN) and the meiotic index (MI) in the tetrad phase in synthetic wheat accessions and cultivars ( Triticum aestivum ) stored at the Germplasm Bank of Embrapa Trigo (Brazil), in order to identify and select genetically stable accessions for plant improvement. Five plants were collected by genotype, prior to anthesis, and the tissues were fixed in Carnoy solution. Cytological slides were prepared by the smash method, and the cells were dyed with 1% acetocarmine and observed under an optical microscope. Presence of MN was observed in all genotypes analyzed, and variability of genetic stability was reported in the two years of analysis. In 2014, the highest MI of synthetic wheat accessions was 96.86% and the lowest was 46.32%. In 2015, the highest MI was 96.60% and the lowest was 47.96%. Based on the results, some genotypes were considered meiotically stable and suitable for use in wheat breeding programs

Principais genes envolvidos na resistência genética de trigo à giberela (Gibberella zeae).

Giberela é uma das principais doenças fúngicas do trigo. Além de reduzir a produtividade, pode produzir micotoxinas que acometem a qualidade dos grãos, bem como riscos para a saúde humana e animal

Genetic stability in interspecific hybridizations of wheat populations determined by meiotic index and pollen viability.

Estabilidade genética em hibridizações interespecíficas de populações de trigo estimada por índice meiótico e viabilidade polínica. O objetivo do estudo foi verificar a estabilidade genética, determinando-se o Índice Meiótico (IM) e a viabilidade polínica em populações segregantes F1RC2, oriundas do cruzamento entre trigos sintéticos e cultivares comerciais de trigo, que visam introgressão/resistência genética. Para o IM, três espigas foram coletadas por genótipo, antes da antese, e fixadas em Carnoy. As lâminas citológicas foram preparadas pelo método de maceração com corante carmim acético 1%, observadas em microscópio ótico e analisadas tétrades normais e com micronúcleos. Para a via bilidade polínica, as espigas foram coletadas no estágio de grãos de pólen maduro. O procedimento metodológico foi semelhante ao das tétrades, avaliando-se: grãos de pólen viáveis, com pouco amido, com presença de dois poros, tamanhos diferentes e inviáveis. O tamanho dos grãos de pólen foi medido pelo programa Axion Vision. Todas as populações segregantes apresentaram IM acima de 90% e viabilidade polínica elevada (acima de 85%), refletindo comportamento meiótico estável. Quanto à variação no tamanho, o cruzamento CIGM90.909/BRS 179 apresentou grãos de pólen com 58,43 μm e CIGM93.298/BRS Guamirim, 47,15 μm. Com base nos resultados, as populações segregantes de trigo apresentam-se meioticamente estáveis e adequadas para seguirem em programas de melhoramento de trigo e incorporação de novos genes importantes. Palavras-chave: Comportamento meiótico; Retrocruzamentos; Trigo sintético; Triticum estivum The objective of this study was to evaluate genetic stability by determining the meiotic index (MI) and pollen viability in F1RC2 segregating populations, obtained by the crosses between wheat commercial cultivars and synthetic wheat, aimed at introgression/genetic resistance. For MI, three ears were collected per genotype, before anthesis, and they were fixed in Carnoy?s solution. The cytological slides were prepared by crushing the anthers and staining with 1% acetocarmine, and the normal tetrads and the ones with micronuclei were observed under a light microscope. For pollen viability, the ears were collected at the stage of mature pollen grain. The methodological procedure was similar to that of the tetrads, evaluating the pollen grains as viable, with little starch, with two pores, different sizes and non-viable. The pollen grain size was measured by the Axion Vision software. All the segregating populations with MI above 90% and high pollen viability (above 85%) reflected a stable meiotic behavior. About the variation in size, the CIGM90.909/BRS 179 cross showed pollen grains with 58.43 μm and CIGM93.298/BRS Guamirim, 47.15 μm. According to the results, wheat segregating populations were considered meiotically stable and suitable for use in wheat breeding programs and for incorporation of new important genes. Key words: Backcrosses; Meiotic behavior; Synthetic wheat; Triticum estivu

Diversidade genética em trigos sintéticos usando marcadores moleculares.

Editores técnicos: Rodrigo Cezar Franzon, Caroline Marques Castro, Alexandre Floriani Ramos, Sueli Correa Marques de Mello. SIRGEALC

Transferibilidade de marcadores microssatélites em aveia.

Editores técnicos: Rodrigo Cezar Franzon, Caroline Marques Castro, Alexandre Floriani Ramos, Sueli Correa Marques de Mello. SIRGEALC