Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Tocopherol contribution to the resistance against storage pest Prostephanus truncatus in maize(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024-12-02) Aguirre Espinoza, Carlos; García Lara, Silverio; emimmayorquin; Mora Vásquez, Soledad; School of Engineering and Sciences; Campus Monterrey; Gonzalez Rodriguez, America TzitzikiProstephanus truncatus infestation can cause losses as high as 80% on stored maize. Sources of resistance against this pest are related to the antioxidant capacity of the pericarp and aleurone layer structures, mainly due to phenolic acids content and their derivatives. Nonetheless, there is not enough information about the germ structure or the liposoluble antioxidants, such as tocopherols. To determine the contribution of tocopherols and liposoluble antioxidant capacity to the resistance against P. truncatus, thirteen genotypes of maize were tested in two confined bioassays (n=3). The first was to assess the susceptibility of each genotype. The second was with the enriched structure of the germ to gather information on damage and development of P. truncatus on this structure. Seven susceptibility parameters were recorded 7 and 60 days after infestation, and ten genotypes were selected based on a Susceptibility Selection Index, with five recognized as resistant and five as susceptible. HPLC-FLD was used to determine the content of tocopherols (δT, γT, and αT), and an ORAC assay was performed to measure the lipophilic antioxidant capacity among the ten genotypes selected. All Population 84 genotypes exhibited less damage by P. truncatus and were categorized as resistant. Three Population 84 genotypes were selected: P84C0Y (SI = 0.17), P84C4W (SI = 0.27; highest tocopherol content, 39.58 mg/kg; high L-AC, 429.04 μmol TE/g), and P84C4Y (SI = 0.51). Two selected genotypes previously recognized as susceptible were classified as resistant: Pink Creole (SI = 0.39; high tocopherol content 39.40 mg/kg; highest L-AC, 488.30 μmol TE/g) and Don Goyo (SI = 0.55). The most susceptible genotype was Red Creole (SI = 3.56; lowest L-AC, 205.48 μmol TE/g), the remaining 4 susceptible varieties selected were Peru2 (SI = 1.23), NAYA29B (SI = 1.07), Panchito (SI = 1.00; lowest tocopherol content, 11.21 mg/kg; low L-AC, 250.4 μmol TE/g), and Pozolero (SI = 0.97). Additionally, a strong correlation (p > 0.01) demonstrated that a short-length bioassay (7 days) can be comparable to a full-length bioassay (60 days). Both can measure a genotype susceptibility to P. truncatus based on weight loss, but only a full-length bioassay can provide information on adult emergence.
- Contribution of the maize germ (Zea mays L.) to the resistance to the postharvest pests Sitophilus zeamais and Prostephanus truncatus.(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-06-12) González Leyzaola, Alán; GARCIA LARA, SILVERIO; 123152; García Lara, Silverio; lagdtorre, emipsanchez; Winkler, Robert; Escuela de Ingeniería y Ciencias; Campus Monterrey; López Castillo, Laura MargaritaMaize (Zea Mays L.) is the most important cereal in terms of production. The maize weevil (Sitophilus zeamais) and the large grain borer (Prostephanus truncatus) are the two main postharvest insect pests that affect maize, causing losses as high as 80%. Factors attributed to resistance of maize kernels against insect pests have been widely studied in kernel structures such as pericarp, aleurone layer and endosperm. However, one structure that hasn’t been studied in this area is the germ. The aim of this study was to evaluate the contribution of the maize germ to the resistance to the attack of the postharvest insect pests S. zeamais and P. truncatus. For this purpose, we performed kernel-insect interaction assays with a duration of 60 days, testing both postharvest pests and 14 maize genotypes. For this work, we considered whole kernels and the hand-dissected germ. We recorded the main suceptibility parameters: grain weight loss, mortality rate, adult progeny and the mean development time of the pests. In order to define a group of possible metabolites which could be implicated in this resistance, we evaluated the chromatographic profiles (HPLC-DAD) of the 14 genotypes in term of phenolic compounds, in free and bound forms. We also evaluated the profile of tocopherols, phytosterols and fatty acids. Finally, we established the correlation between the susceptibility parameters determined in the insect bioassays and the evaluated compounds. Surprisingly, in the maize germ assays, although oviposition was observed after 60 days, there was no evidence of adult or larvae emergence of both pests. Furthermore, oleic acid showed a positive correlation with germ weight loss in both insect pests, while palmitic acid had a negative correlation of this parameter only in P. truncatus. Statistical differences in concentration of compounds from basal state and infested samples were detected in free and bound phenolics and liposoluble compounds. These findings provide strong evidence of an important contribution of the maize germ in the resistance against S. zeamais and P. truncatus by possible detrimental effects on early stages of development. This information could be helpful in the development of new strategies for the protection of maize kernels against S. zeamais and P. truncatus.
