Análises biométricas e moleculares visando o desenvolvimento de linhagens de soja com alto teor protéico e produtivas

• Ano de defesa: 2008
• Autor(a) principal: Piovesan, Newton Deniz
• Orientador(a): Moreira, Maurílio Alves
• Banca de defesa: Guimarães, Cláudia Teixeira , Carneiro, José Eustáquio de Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Soja; Melhoramento genético; SAM teor protéico
• Palavras-chave em Inglês: Soybean breeding; Protein content
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA MOLECULAR E DE MICROORGANISMOS
• Link de acesso: http://locus.ufv.br/handle/123456789/1283

The improvement of the productive potential of soybean cultivars is the main objective of all the genetic breeding programs conducted in the country. However, in some breeding programs, the increase of the protein content in grains has been focused. In order to develop productive varieties with high protein content, this work had the following specific objectives: a) use different selection strategies for the prediction of gains in grain production (PROD), plant height in maturation (APM), number of days for maturation (NDM), protein content (PTN) and oil content (OL); b) compare different selection criteria through selection indices; and c) identify SSR markers linked to the QTL s which contribute for the increase of the protein content in a population of almost isogenic lineages (NIL s). To achieve these objectives, two populations were used in this work; the first one, called selection population, derived from the partial backcrossing involving a lineage with high protein content and another presenting resistance to the glyfosate herbicide. In the segregant population RC1F4, the genetic parameters were estimated and the selection was carried out during three cycles, due to the agricultural year. In the first phase, the following strategies were used: selection between (SE), selection between and inside (SED), massal selection (SM) and combined selection (SC). The heritability, in the restrict sense inside, presented reduced value for PROD (8.1%), affecting the selection efficiency at the individual level. In the second phase, 205 pre-selected progenies were used for PROD, in the simultaneous selection of families for the characteristics PROD, PTN and OL employing the selection criteria based upon the indices of Smith and Hazel (SH), Kempthorne and Nordskog (KN), Pesek and Baker (PB) and Pesek and Baker, generalized by Tai (PB-Tai). Significant genetic correlations were detected only for PTN × OL, with the value of -0.398. It was performed the selection of the 40 families that maximized gains for PTN and provided moderate gains in PROD and minimum reduction in OL. The PB-Tai index presented better predictions as to the proposed objective, with gains of 4.2%, 8.9% e -3.68%, while the direct selection for PTN provided gains of 4.45%, 3.91% and -5.85% for PTN, PROD and OL, respectively. In the third phase, it was carried out the genetic parameter estimation and the gain prediction for PROD and PTN, with family and plant information, through the use of different strategies and selection criteria. For PTN, the restricted heritability between was of 60.7% (higher than the restrict inside, which was of 15.6%), which revealed a small superiority of gains provided by the strategies that employed the information of the individual. In this phase, the combination of the simultaneous selection using the classic index of Smith and Hazel, with the selection used between and inside, provided significant gains for PTN and PROD, lower, however, than those of the second phase, due to the reduction of the genetic variability. The third selection cycle was carried out in the year of 2006/2007, in an essay that used the DBC, with the 84 families RC1F4:6 selected in the first cycle and multiplied in the second cycle, with the objective of increasing PTN and PROD and reducing NDM. For such, the simultaneous selection was used, based upon the indices of SH, PB, KN and PB-Tai. Again, the PB-Tai index was the most suitable selection criterion, because it provided the selection of a group of progenies which presented, in average, higher productivity and smaller cycle than the commercial variety Monarca and another group, with higher PTN and lower NDM, in comparison to Monarca. A mapping study was carried out, in the second population, in order to identify SSR markers associated to the QTL s, which control the protein content in soybean grains. This population, called mapping population, was composed of 168 NIL s (isolines in the generation RC4F6) and was achieved from the backcrossing between the BARC-8 genotype, with high protein content, and the recurrent Monarca variety. Out of the 350 primers of microsatellites used in the parents, only 20 were polymorphic in the population of NIL s. Using the association analysis by the method of the ANOVA and the simple linear regression, two markers were found (Satt 239 and Satt 384), associated to QTL s, which explained 19.04% and 7.42% of the phenotype variation. With the use of the multiple linear regression, with the stepwise procedure, these very QTL s were maintained and explained 26.01% of the phenotypical variation. With the use of the mapping by simple interval in the GL E, it was estimated the additive effect of the QTL (+ 0.54) in character expression and it was determined the position of the marker in relation to the QTL. This mark was placed very near to the QTL or on it, resulting in an extremely trustable mark for future works of assisted selection.