Pré-melhoramento de abóbora (Cucurbita moschata Duch.) Visando biofortificação em carotenoides

• Autor(a) principal: Lima Neto, Izaias da Silva
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1200
• topic: Cucurbita moschata; Biofortificação; Carotenoides; Recursos genéticos; Melhoramento genético; Cucurbita moschata; Biofortificação; Carotenoides; Recursos genéticos; Melhoramento genético; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

Hipovitaminosis A has been attributed to inadequate consumption of preformed vitamin A or carotenoids, due socioeconomic deprivations, food taboos or inadequate nutritional orientation. Thus, biofortification of vegetables with vitamin A carotenoid precursors is a viable alternative to its eradication. The pumpkin (Cucurbita moschata Duch.) is considered an important source of carotenoids, mainly β-carotene. Its consumption minimizes the effects caused by hipovitaminosis A in the human body. Therefore, characterization of the pumpkin germplasm based on the composition of carotenoids and target morpho-agronomic traits is important, seeking to make these genetic resources available for breeding programs (pre-breeding). In pumpkins it is possible to observe a high correlation between flesh color and concentration of carotenoids, which allows for indirect estimates of β-carotene concentration via colorimetric parameters. Therefore, the objective of this work was to characterize a pumpkin germplasm samples from the Vegetable Germplasm Bank of the Federal University of Viçosa (BGH/UFV), with respect to morphoagronomic traits and composition of carotenoids so as to identify parents for use in breeding programs and to estimate regression equations based on colorimetric parameters for establishing a simple and efficient methodology for indirect estimation of β-carotene concentration in biofortification programs. The characterization experiment was conducted in the Experimental Field of the Plant Science Department at UFV, Viçosa-MG, Brazil, from January to July of 2011. A total of 55 accessions were used from the BGH/UFV from various geographic regions, and four commercial cultivars as control. One hundred descriptors involving the seedling, plant, fruit and seed were applied to quantify genetic diversity. Based on indirect estimates of total carotenoids (TC) and lutein, a group of 16 accessions was selected, from which carotenoids were extracted and quantified by spectrophotometry and high performance liquid chromatography (HPLC). The regression equations were adjusted based on colorimetric data and direct determination of β-carotene via HPLC, using the Genes software. The pumpkin accessions stored in the BGH/UFV have high variability regarding composition of carotenoids [β-carotene (from 12.8 to 286.7 μg g-1), α- carotene (from 8.1 to 153.8 μg g-1), lutein (from 0.04 to 1.32 μg g-1) and TC (from 27.8 to 506.6 μg g-1)] as well as for the main agronomic traits and fruit morphology. The magnitude found for carotenoid concentration was higher than that previously reported found for the pumpkin crop among accessions previously evaluated. Upon selection based on genetic diversity and per se behavior, four parents were selected with high frequency of favorable characteristics and genetically divergent (BGH-6997, BGH- 7003, BGH-7671, and BGH-7765), which may be inserted in pumpkin breeding programs for developing biofortified and productive cultivars. Fifty-seven regression equations were generated based on the colorimetric parameters a*, b* and H* (r > 0.7 with β-carotene). Seven regression equations, including the power (a*), exponential (a*), logarithmic (a*) and multiple (a* and H*) models were efficient for indirectly determining the concentration of β-carotene in pumpkin (R2 > 90%). Use of the power equation based on the colorimetric parameter a* is recommended because of its use accuracy (R2 = 91.7%) and simplicity. The proposed method is inexpensive, fast and efficient in indirectly estimating the concentration of β-carotene, particularly for evaluations involving a large number of genotypes in biofortification programs.