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Genetic improvement of the fatty acid profile of corn oil

Recibido 24 de agosto de 2017 // Aceptado 15 de enero de 2018 // Publicado online 09 de octubre de 2019
DELUCCHI, C.1; PERCIBALDI, M.1,2; TREJO, M.2; EYHÉRABIDE, G.1,2(*)

 

ABSTRACT

Maize oil is a co-product of the dry and wet milling industry, highly appreciated for its nutritional quality. Saturated fatty acids increase levels of total cholesterol, while unsaturated acids such as oleic acid, decrease blood levels of LDL-cholesterol (“bad” cholesterol) and increase HDL-cholesterol (“good” cholesterol). The general objective was to develop and improve maize populations for greater relative content of oleic acid in the embryo, through phenotypic recurrent selection. In order to evaluate the response to selection, the averages of relative fatty acid composition of S1 ear kernels were compared across three consecutive cycles of selection. The method of selection applied was effective to increase the percentage of oleic acid. In addition, a panel of elite maize inbred lines developed by INTA Pergamino, was evaluated in order to determine the genetic variability and heritability of the acidic composition of oil, for future mapping association studies. The analysis of the estimated components of variance allowed us to conclude that the genotypic component contributed most to the phenotypic variability. The high values of heritability obtained indicated a strong reliability of the phenotyping carried out for the search of associations with molecular markers. Given the classification of fatty acids according to heterotic groups, a high diversity between groups was detected, and a greater oleic acid content in the germplasm of Argentine origin compared with the American. Furthermore, three studies at the molecular level were performed. The first consisted in the search of molecular markers, SSR, associated with the relative composition of fatty acids from populations resulting of the crossing of two contrasting lines. In the second study, we determined changes in the frequency of SSR between cycles of recurrent selection of a maize population to increase the relative percentage of oleic acid. In the third study, we evaluated the use of molecular markers in the conversion of elite maize lines to high oleic versions. QTLs for differential oleic and linoleic acid content were detected on chromosome 6, a result consistent with those obtained through variations in allele frequencies over the cycles of selection evaluated. A strong association was also found between the relative content of oleic acid and the molecular markers analyzed in plants from lines LP29 and LP214, to which the high oleic character is being incorporated by means of crossings and backcrosses. The relevance of use of these markers in assisted selection programs for high oleic maize is thus indicated.

Keywords: oil quality, oleic acid, molecular markers.

 

1Instituto Nacional de Tecnología Agropecuaria (INTA), Estación Experimental Agropecuaria (EEA) INTA Pergamino, Ruta 32 km 4,5, CC 32, 2700 Pergamino, Argentina. Correo electrónico: delucchi.carla@inta.gob.ar
2Universidad Nacional Noroeste Buenos Aires (UNNOBA). Correo electrónico: percibaldi.nora@inta.gob.ar
(*)Redactores de la compilación. El grupo de trabajo en sus diferentes etapas contó con la participación de Francisco Borrás, Carla Delucchi, Guillermo Eyhérabide, María José Hourquescos, Ana Rosa Schlatter, Mabel Percibaldi, José Robutti, Sofía Olmos, Laura Orcellet, María Guillermina Ruiz y Manuel Trejo.

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