Physiological and biochemical changes on rice plants supplied with glutamate in response to Pyricularia oryzae infection

• Ano de defesa: 2018
• Autor(a) principal: Dias, Carla da Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Brusone; Fotossíntese; Antioxidantes; Arroz - Doenças e pragas - Controle biológico; Fisiologia Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/27563

Considering 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.