Genome-wide association for b-glucan content and characterization of the Cellulose synthase-like F6 gene in oats

• Ano de defesa: 2020
• Autor(a) principal: Zimmer, Cristiano Mathias
• Orientador(a): Federizzi, Luiz Carlos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Palavras-chave em Português: Aveia; Melhoramento genético vegetal; Genoma; Gene
• Palavras-chave em Inglês: Avena sativa L.; Genome-wide association mapping; B-glucan content; Kernel shape
• Link de acesso: http://hdl.handle.net/10183/232270

The b-glucan content has been one of the main goals of oat breeding programs worldwide. However, the loci controlling this trait and their interaction with the environmental conditions are not completely understood to date, especially in subtropical environments. In this sense, the main objectives of this study were: i) to identify genomic regions associated with b-glucan content in elite oat germplasm adapted to subtropical environments; ii) to identify genomic regions controlling kernel shape-related traits and verify its association with b-glucan content on oats; iii) to characterize and quantify the absolute expression of the Cellulose synthase-like F6 gene in oat genotypes with contrasting b-glucan content; and iv) to characterize the b-glucan formation in primary and secondary oat kernels harvested in different planting dates and years. An oat panel composed by 413 genotypes was genotyped and assessed in different environments. Genome-wide association mappings were performed using individual and multi- environment approaches. Quantitative trait loci (QTL) associated with b-glucan content were identified on Mrg02, Mrg06, Mrg11, Mrg12, Mrg19, and Mrg20 consensus groups. QTL associated with kernel shape-related traits were detected on Mrg06, Mrg13, Mrg21, and Mrg24 consensus groups. Kernel width and kernel thickness traits, which were phenotypically and genetically correlated, share a genomic region in common on Mrg13 and are negatively correlated with b-glucan content. The oat b-glucan content varied between primary and secondary kernels according to the genotype and environmental conditions. Under unfavorable conditions, some genotypes can present higher b-glucan content in secondary kernels than in primary ones. The high number of CslF6 transcripts was not a guarantee of high b-glucan content in oats. The CslF6 gene expression was highly influenced by the genotype, environmental conditions, and kernel developmental stage. The third exon of the CslF6 gene, which corresponds to the CslF6 motif, has 1767 bases pair in oats, regardless of the subgenome. The CslF6 motif of the CslF6-AA and CslF6-DD genes encodes the same amino acid sequence. The CslF6-CC gene showed 13 amino acid changes in the CslF6 motif when compared to the other ones. Single nucleotide polymorphisms were not identified in the CslF6 homoeologs among the assessed genotypes, indicating that the CslF6 proteins with the same functional properties are encoded in these genotypes. The results presented in this study contribute to improve the understanding of the b-glucan content in oats under subtropical conditions.