Fatores de estresse na germinação de sementes e na propagação in vitro de Passiflora edulis Sims f. flavicarpa Degener

• Autor(a) principal: Alexandre, Rodrigo Sobreira
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1160
• topic: Passiflora edulis; Cultura de tecidos; Propagação seminífera; Estresse; Passiflora edulis; Tissue culture; Propagation; Stress; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The oxidative stress results into reaction series of the reactive oxygen species (ROS) that are considered as detrimental to biological membranes. In addition, the tissues can produce and liberate gases such as the ethylene and CO2, as being the first one responsible for the chlorosis, senescence and leaf abscission. High irradiance on the photosynthesizing tissues results into a stress reaction series so-called photoinhibition. Using the phytoregulators can also change the physiology of the plant, therefore inducing it to stressful condition. Under normal physiologic conditions, the production of those radicals is appropriately controlled by deintoxicant agents. In the species P. edulis f. flavicarpa, the germination of the seeds is genotype-dependent, whereas storage is beneficial to their germination. BAP affects the absorption of mineral nutrients through the hypocotyledonous segments, whereas the soaking time in this cytocinin is related to the formation of organogenetic structures. The irradiance incidence on the hypocotyledonous segments and stem apexes affects the ethylene emission rate and CO2. There is a relationship between the ethylene production and biosynthesis or leaf pigment degradations. In the organogenetic process, a direct relationship occurs between the sprout formations at the highest irradiances and the increase in POD activity. The growth of the stem apexes is related to inactivation of the enzymes SOD and CAT. Yet, increasing MDA levels indicate that only the increased CAT activity is not enough to remove ROS. The increase in the irradiance levels affects the potential quantum production of FSII, whereas this one is indicated for measuring the plantlet stress levels because it shows a behavior similar to photosynthetic activity . The photosynthetic activity evaluation system contributed to the analysis of the passion fruit plant plantlets cropped in vitro. In this study, hypocotyledonous segments and the P. edulis f. flavicarpa plantlets showed a better adaptation to the lowest irradiances.