Melhoramento genético da soja (Glycine max (L.) Merrill) para baixo teor de ácido linolênico

• Autor(a) principal: Matta, Lorêta Buuda da
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4494
• topic: Ácido linolênico; Soja; Fingerprinting; Linolenic acid; Soybean; Fingerprinting; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The use of the soybean oil for industrial and nutritional purposes is defined by the composition of the fatty acids present in the seeds, which directly affect the physical and chemical characteristics and the nutritional value of the oil produced. The reduction of the linolenic acid content is associated with the increase of the oxidative stability and the improvement of the oil taste. This work takes part in the soybean breeding program of the BIOAGRO/UFV and its objective was to achieve productive soybean lineages, with low content of linolenic acid, having as donator the American access A29. For such, the following stages were carried out: (1) non-destructive analysis of the linolenic content of seeds in two contrasting F2 populations for this characteristic; (2) selection of seeds with lower contents of linolenic acid of each crossing; (3) evaluation of the genetic variability, herdabilities, selection gains, predicted and realized, for the content of linolenic acid in both F2 populations studied; (4) performance of the fingerprinting of the F2 plants selected with microsatellite markers; (5) confirmation of the low content of linolenic acid present in the F3 seeds; (6) determination of the genetic divergence between recurrent parents and parents that are donators of alleles that condition the low content of linolenic acid; (7) selection, with the help of molecular markers, of hybrids derivative from genotypes which are genetically more similar to the lineages of the COODETEC, and which confirmed the linolenic acid low content condition in the F3 seeds. Both F2 populations presented high heritabilities for the linolenic acid content, suggesting that they are adequate for the achievement of gains for the low content of linolenic acid, and that the selection can be performed in precocious generations. Only the F2 population of the A29 x Tucunaré crossing presented heritability higher than 50%, when estimated by parent-child regression. Although the F2 population from the A29 x Tucunaré crossing presented higher predicted and realized gains, due to its high genetic variability, the 30 individuals selected presented linolenic acid contents below 2,5%. The different environmental conditions in which the F2 and F3 populations from the A29 x CS303TNKCA crossing were carried out provided a low realized gain. The study on genetic divergence showed that the parents are different from one another, and the genotype A29, donator of alleles for very low linolenic contents, was the most divergent. However, the lineages from the COODETEC were very similar due to the genetic background proximity of such lineages. The DNA fingerprinting allowed the identification of the most similar individuals as to the COODETEC lineages. It was possible to select, in both F2 populations studied, four individuals which are closer to the COODETEC lineages and that confirmed the low contents of linolenic acid in the F3 generation.