Fisiologia Vegetal
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/185
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Resultados da Pesquisa
Item Physiological and biochemical changes on rice plants supplied with glutamate in response to Pyricularia oryzae infection(Universidade Federal de Viçosa, 2018-07-20) Dias, Carla da Silva; Rodrigues, Fabrício Ávila; http://lattes.cnpq.br/0497776503129914Considering the importance of blast, caused by Pyricularia oryzae, to decrease rice yield worldwide, this study aimed to assess the photosynthetic performance (leaf gas exchange and chlorophyll (Chl) a fluorescence as well as the photosynthetic pigments concentration), the activities of antioxidant enzymes (ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione-S-transferase (GST)) and concentrations of hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) in leaves of plants non-supplied (-Glu) or supplied (+Glu) with glutamate (Glu). Blast severity and the number of lesions per cm 2 of leaf were significantly lower for +Glu plants in comparison to -Glu plants. On the infected leaves of +Glu plants, the values for internal CO 2 concentration were lower while the values for net carbon assimilation rate, stomatal conductance as well as for the concentrations of Chl a, Chl b, and carotenoids were higher in comparison to infected leaves of -Glu plants. The functionality of the photosynthetic apparatus was preserved on the infected leaves of +Glu plants. The activities of CAT, GPX, GR, POX, and SOD increased on the infected leaves of both -Glu and +Glu plants compared to their non-inoculated counterparts, but their activities were lower for +Glu plants. The lower activities of these antioxidative enzymes was triggered by the reduced hydrogen peroxide concentration on the infected leaves of +Glu plants that resulted in lower malondialdehyde concentration. For inoculated +Glu plants, the activities of β-1-3- glucanase, chitinase, phenylalanine ammonia-lyase, and polyphenoloxidases as well as the concentrations of total soluble phenolics and lignin-thioglycolic acid derivatives were significantly higher for inoculated +Glu plants in comparison to inoculated -Glu ones. Based on the data from the present study, it can be concluded that photosynthesis was less impaired on plants supplied with glutamate and infected by P. oryzae due to the lower biochemical constraints for CO 2 fixation. There was a need for lower activities of reactive oxygen species scavenging enzymes on the infected leaves of plants supplied with glutamate due to the lower oxidative stress as a result of P. oryzae infection. Moreover, blast severity was reduced on Glu supplied plants due to an increase on the activities of defense enzymes and high concentrations of phenolics and lignin.Item Leaf gas exchange and chlorophyll a fluorescence imaging of soybean leaves Infected with Colletotrichum truncatum(Universidade Federal de Viçosa, 2015-02-19) Dias, Carla da Silva; Rodrigues, Fabrício de Ávila; http://lattes.cnpq.br/0497776503129914Anthracnose, caused by Colletotrichum truncatum, is one of the most important soybean diseases worldwide. However, there are no studies evaluating the physiological changes affecting this pathossystem. Therefore, one approach to evaluating events that occur at the site of infection and near the infected area on the leaf, over time, will contribute to a better understanding of the host-plant interaction and photosynthetic activity. The present study aimed to investigate chlorophyll a fluorescence parameters at injured and adjacent areas and the related changes in gas exchange and evaluation of photosynthetic pigments in soybean plants inoculated or non-inoculated with C. truncatum. There were no significant differences regarding gas exchange parameters for inoculated plants. However, there was a reduction in the concentration of Chl a, Chl b e Chl total (a + b) of inoculated plants in the 72 and 144 hours after inoculation (hai). Reduction in chlorophyll a fluorescence parameters to as initial fluorescence (Fo), maximal fluorescence (Fm), maximal photosystem II quantum yield (Fv/ Fm), quantum yield of regulated energy dissipation Y (NPQ) and coefficient non-photochemical (qN), and an increase in the Effective PSII quantum yield Y (II), quantum yield of non- regulated energy dissipation (NO) and photochemical coefficient (qP) in the symptomatic area plants inoculated. However, these parameters have undergone minor adjacent areas of inoculated plants, differing only in a few days. Demonstrating a smaller effect of the pathogen in adjacent.